# Key Post: Underfloor Heating



## BlueSpud

I am doing some renovation on my house, including replacing floors and converting from oil to gas.  I am considering underfloor heating as an alternative to rads, as it will free up some wall space and I am told, give a more even heat.  I have 2 kids under 4 so a warm floor is attractive at least for a few years.  Can any of you guys comment on your experiences with hot-water underfloor heating.  Cost, effectiveness, quality, product-name & installer etc.

Thanks.


----------



## MOB

*Underfloor Heating*

It is very comfortable.  It doesn't seem to be too dear; we put it in from new, so I am not able to compare it to the cost of heating with rads, but we manage fine for all hot water plus house heating (a good sized house) on a little over two fills of oil per annum.

It is particularly comfortable on tiled floors, and ideal in bathrooms.

One limitation is that if you are away for a few days and you come back to a cold house, you cannot have an instant blast of heat - it brings the heat up slowly.  But this is a small limitation in practice.

Another limitation is that some people are particularly fond of plonking their rump on a radiator when they come in from the cold - you can't do that when the heating is just a slightly warm floor.

Make sure your new concrete floors are insulated both underneath and at the sides (to stop heat being soaked up by the walls).  Needless to say, get a reputable contractor in to do the floor heating, and get his/her advice before staring work on the floor.


----------



## ferryman

*heating*

Anyone know of a good website that deals with plumbing/heating?


----------



## BlueSpud

*Re: Underfloor Heating*

Thanks MOB.

Anyone got comments on products & installers?


----------



## LC

*Underfloor Heating*

I lived in Paris for a number of years and underfloor heating had been very much the thing there for apartment buildings built during the 70's and 80's.   However a number of people there told me that the practice had been more or less abandoned, as it was found to adversely affect people with rheumatoid/ arthritic conditions.  May I stress that this is purely anecdotal, but it may be something you want to look into further before you make your decision.


----------



## Karl

*Underfloor Heating*

Thanks for the link Stobear.

In later years if there is a problem I assume the whole floor has to come up? Has anyone experienced any reliability issues?


----------



## heinbloed

*underfloor heating +rheumatoid*

Rheumatoid people usually like the warmth, even when kryo-therapy is used for treatment.What would be more trouble some is walking on concrete ore tiles ,warm or not, since the older we get the less distance there is between the joints making walking painful.Use timber flooring in connection with underfloor heating . It works with the aid of heat reflector sheets.Timber is probably nicer for the kids as well and they wont break that many cups.


----------



## alpha

*Reliability*

I've it installed in a new house 4 years now. Love it and would highly recommend it.

From research before I built I don't think reliability is too much of a concern. If you use a reliable system. I went with a company called polytherm and a plumber who knew what he was doing. Reliable suppliers have usually been in business on the continent for decades. Remember underfloor heating is only new to Ireland but has been in use for decades and is a proven technology.

The pipes that are used are plastic with various layers to prevent oxygen permeating the pipes. This helps to reduce any corrosion over the years. There are no moving parts buried in the floor so leaks are about the only thing that can go wrong. A smart plumber will lay the pipes; connect to water supply and place the system under pressure for a day or two to check for leaks before the floor goes down. When the concrete floor goes down leave it for weeks before putting down the floor covering. This will give time for any leaks caused by your builder pouring concrete (Shouldn't happen really but better safe than sorry) to show through as damp on the floor.

Expense wise it is a bit dearer than going with radiators but not all that much. You don’t have the cost of the radiators or copper piping.


----------



## valeriana

*cost*

Can anyone give a (very approximate) estimate of what it might cost to instal underfloor heating in a 3-bed semi-d?


----------



## heinbloed

*costs*

Give more info : m2,heating zones,insulation requirement (upper floor or down stairs ),what cover i.e. timber or concrete/tiles. Would it be a DIY project, which heating source resp. what run temperature , is a new boiler necessary ?


----------



## Marion

*I have copied these posts by various users from another topic. Thanks to all.*

*kfpg*
I have read loads of internet material on the use of underfloor heating in conjunction with timber floors.

Plenty of advice says use only manufactured laminated boards, but equally as many sites say it is ok to use solid timber flooring as long as the concrete floor is fully dried & the timber is 'seasoned' in the house with the heat on for a number of weeks.

As I would prefer to use solid board I was wondering if any of you had gone down the same route with something like a 17mm to 19mm thick board. If so how successful has it been? any useful advice?........thanks...

JB

Actual Experience kfpg. I have experienced problems with our bathroom underfloor heating (under floor tiles) which would put me off recommending it to others or putting it anywhere else in the house.

*kfpg*
Underfloor Problems I am surprised to hear that as the most ideal flooring to use is considered to be tile, I guess the problem is something other than heat not radiating through??

*EAMONN66*

Re: Underfloor Problems two thoughts,
as JB only has it in the bathroom, he/she might have electric u/f heating which would have a lot more potential for going wrong than water based system.

i'm not an expert but have fitted a couple of floors for myself over the years. i would guess that there are two potential issues with wood floors

if you have a solid floor laid over battens there will be a gap of about an inch under the floor which would act as an insulator thereby loosing you some of the heat from the cement screed below.

if you lay a laminate floor, these normally go down on top of foam which does the same thing

the other issue is shrinkage which causes gaps and creaks

using tiles or even stone floors gets around these problems as the heat radiates up through the pipes,screed and tiles as one single unit with no loss.

somewood floor manufacturers claim their product is suitable. it would be interesting to hear some first hand experiences

*JB*
Underfloor heating If its a fault with the product say the underfloor mat, or one of the sensors, then its under guarantee. But the whole floor would have to be lifted, an electrician called to disconnect, a replacement obtained, electrician and again a tiler employed to redo the floor. Would the floor look the same? Probably not so I'll leave it. If it was a wooden floor I might have been easier.

On their guide booklet I did read that if you are using on a wooden floor then you have to be careful about the temp you set the heating at - ties in with what Eamonn66 says above.

*kfpg*
Re:Unerfloor Problems Interesting Eamon, thanks.

Regarding mounting timber floors on battens I totally agree the first thing the underfloor pipes will do is heat the air gap between concrete and underneath of board (a waste of energy!!).
I was advised by one company that they don't lay on battens but directly to concrete screed (fully dried out) and with no insulation layer.
Not sure about this in reality but imagine very level screed would be a priority as well as the obvious need to fully dry the floor before laying timber.

*EAMONN66*
Re: Re:Unerfloor Problems ive seen it done, might be ok

my own experience was that i laid a solid unfinished maple floor in my own house (radiators not u/f) on mdf battens spaced 10 inches apart with a plastic sheet in between. i also left the wood a couple of weeks to dry out. it was hard work even using a portanailer which pulls the boards together as it is nailing (i found that most boards over 2 ft were slightly warped ). i dont know how that could be gotten around if gluing direct to cement. over time some creaks have developed as the boards dried out and the nails get stretched , esp in winter when the heating is on. the uneven cement floor beneath probably does'nt help. if i was doing it again, i would use solid mdf sheets , glue and millions of nails that would eliminate the air gap and give it a more solid feel under your feet.

*EAMONN66*
Re:Unerfloor Problems one thing i forgot

the solid / batten route raises your floor level about 2 inches which means cutting doors ,raising skirtings etc. in my case i had to cut the bottom (inc the seal) off my halldoor which meant getting a porch to seal it back up.

*jameson*

underfloor heating 
I have been living in europe for over 10 years now, in various houses and apartments with water based underfloor heating and wooden floors. I have found it to be a great system and never had a problem with it at all. Only if you spill liquid on the floor then you need to get it dryed up fairly sharpish, as this seeping into the floor could cause problems. You time it to come on probably 1 or 1.5 hours before you need the warm feeling and bingo.

Am planning to build in Ireland next year and underfloor heating with wood floors will definitely be installed. But what I have found in Ireland is that there are very conflicting forms of advice about the different wood products about and how best to use them with the underfloor systems. Don't know if this is to do with the fact it is still a relatively new concept here or a lack of knowledge by some "cowboy" companies or resellers of floors without the proper expertise. The one thing I have found out in Europe is that wood for wooden flooring purposes is rekilned or "dryed out" to a humidity % level of between 6 and 9%, compared to the standard 9 to 12%. Not one single company or shop I spoke to in Ireland so far has mentioned this and when asked to check their products were in the 9-12% range !! According to the advice I have been given this is one of the biggest factors in ensuring that the floors have the best chance of settling properly with the ufh. Unless the product is already at this 6-9% you don't have much chance for rekilning. I think you need to get the stuff direct from the manufactures or producers. I don't claim this advice is gospel or anything but it seems to make sense to me.

*expatexpat*
electric underfloor heating

I have electric underfloor heating under tiles in my bathroom and I love it. It's fantastic to walk on, keeps the temperature in the bathroom nice and comfortable and is not too noticeable on the ESB bill....

*SuzieQ*
wood and moisture

Hardwoods generally are bought at a lower humidity than a typical Irish home - thus warping can be a problem.

Softwoods are the opposite - they usually have a higher moisture content and so are prone to shrinking.

Make sure whatever wood you choose that you lay it out for as long as possible. Block homes take up to a year to dry out totally and while you can't wait a year for flooring - make sure the house is well dried out. Wood homes less drying out t[/b]


----------



## Marion

These posts were supplied by others:

*heinbloed*

I have installed underfloor heating and use a condensing boiler fueled with LPG . LPG is more expensive than oil but the system is so economic that I still use the first filling of the tank ( 1000l) despite it is used for cooking and warm water as well, I guess one fill will last for about 10-12 month . 

One thing that is important when installing it is to forget the recommendation of the manufacturers to install 50mm insulation under the pipes - go for at least 100mm,the more the better .I have used 130mm under the pipes and another 20 mm along them . The pipes are placed in heat deflector sheets,on top of them the solid timber floor.


*Gary*

Hi heinlbloed,
I'm thinking of using underfloor heating myself. Would you mind supplying more info? How many sq ft are you heating, and what sort of usage pattern do you have? Who did you buy from? What thickness are your floor boards? Thanks. 

*heinbloed*

Hi Gary!

I am heating the whole of the house ( 96 squaremeters-roughly 1032.96 squarefeet) with underfloor heating.The thickness of the floorboards is 22 mm, Swedish red deal,B-quality.Supplier was Chadwicks.

The material for the floor heating pipes was from"qualpex"
check the web.The boiler was from "Cork Heat merchants"model"Vokera Hydra"- check www.sedbuk.com/ "Qualpex" shows on their web page different patterns.

For the benefits of my health I went for the more expensive method with the heat deflector sheets giving me the freedom of installing timber floor and not tiles on concrete which I find uncomfortable to walk on. I think I should stress that a well insulated structure is important to get a low cost/ high comfort heating system working .


----------



## sueellen

These posts were supplied by others:-

*carlow
Unregistered User*
*Under floor heating*

Commencing building a dormar bungalow house 
(2700 sq feet) in the near future and I'm considering installing under floor heating (upstairs and downstairs)
I'm aware that the initial expense in higher than the conventional method of radiators, however over 4 - 6 years this cost can be recouped in energy savings on your bills.

One of my concerns is the stories about tiles and floor boards cracking due to the heat.

Can anyone shed some light on this...... 
Is it considered a good option to go under floor heating (cost wise) ?

Are there special tiles/treatements for timber floor boards
that can be used with Under Floor Heating

What companies/products are known to be reliable/efficient


*collieb
Registered User
Re: Under floor heating*

hi carlow,

ive heard a good few stories about these systems as my dad is a plumber and has put a few in lately. He raves about them and reckons if he ever builds another house for himself he would definitely go with underfloor heating.

As far as i know, you are right in saying that the initial expense is higher but that it works out cheaper over time. The system works on the principle that the boiler is always on, thus keeping the underfloor pipes at a minimum temp. all day. Then in the evening or morning, the boiler kicks in at a higher temp and gives a blast of heat that quickly radiates through the room cos the fllor is already warm, and doesnt have to be heated from scratch. Because of this, the room heats quicker than with radiators. in addition, your tiled floors are always warm, meaning that no-one complains of cold floors when they hop out of the bath!

As i understand it, even with wooden fllors, the pipes still have to be laid within a concrete sub-floor, with insulation underneath. Problems have occurred with wooden floors but this is because of bad installation - apparently if the pipes are laid in a concrete sub-floor, and the boiler is commissioned BEFORE the wooden fllor is laid, thus ensuring that the concrtete floor or sub-floor is compeletely dried out, there will be no problems with a wooden fllor laid later. problems only arise when a wooden floor is laid directly onto a still damp concrtete floor with the heating turned on afterwards - with the obvious result of damp rising throught the wooden floor (twisted floorboards etc)

as for products, i know that one reliable one is called 'Heatlink' which is available through heating suppliers. They do everything for you, including working out the heat requirements of each room individually, based on size, walls etc, and then telling you how much pipe should be laid under the floor, at what spacing etc. Also, a good qulaity insulation material is absolutley necesaary under the pipes to stop heat escaping into the ground. 

*Thrifty Knot
Registered User
Re Underfloor heating*

Hi Carlow,

Last year I built a conservatory and installed underfloor heating in it and here's my account:

Advantages - the conservatory does get warm (even in Winter), and the floor is terrific to walk on, especially with bare feet. Also, having no visible rads is great. One more thing, the flor continues to be warm for hours after the heating has been switched off.

However, it takes a long time for the floor to heat up. It would take a good 2 hours compared to 10/12 mins with rads. This is the one disadvantage with it, it takes too damn long to heat the house!

My friend has also put underfloor heating in her house, and because it takes so long to heat up, she has a supersur in the tv room!!!

Cheers 

*tom
Unregistered User
underfloor heating*

I moved into a new apartment which has underfloor heating (under concrete). I laid wooden floors on this - got them from a company called House of Woods, who provided and installed the wood which was guaranteed for underfloor heating (I think they are 'engineered' boards, which is just a step below hardwood floors but they are hardwood on top and look the same.... a million miles away from laminates which I had before. They have a real wood top so it does scratch). Did some separate research on these engineered boards which seemed to confirm that they were the most suitable for underfloor heating.

Experience a year later is excellent - constant even heat throughout the whole apartment, which is the best as I found before with radiators the heat rises from radiator level, so your feet can get cold. Also radiators focus the heat in one area, so if you are sitting beside it,it gets annoying. I have the heating on timer, so no issues about waiting for it to warm up. Nice warm floors to walk on throughout. No radiators. All in all, I couldn't recommend it more. And the wooden floors have behaved impeccably - no warping or movement of any sort (as I have seen before). 

*Bill
Unregistered User
Tiles & wooden floors*

As far as I know, if you want to lay tiles on a floor with underfloor heating installed, the adhesive should be flexible, unlike normal tile adhesive. Sorry I have no more specific details, but I'm sure you can find out more based on that pointer.
As regards timber flooring, certain hardwoods have better thermal insulation values than others, and obviously the higher their insulation the worse it is for allowing heat up from the floor. Again, sorry no specifics, but something to research, and Tom's mention of "engineered" boards definitely sounds interesting.
If you do find out the specifics I'm missing here, would you kindly post them?


*Carlow
Unregistered User
Under Floor heating*

Thanks for all your help!

However we still haven't decided so dont stop the replies!

Carlow 

*Carlow
Unregistered User
Under Floor heating*

From what I hear semi-solid timber floorboards are the best way to go.

*Jim
Unregistered User
underfloor heating*

Is this a big job if you want to install to an existing room, what about future problems, do you have to pull up the whole floor to location the problem? 

*Laoise
Unregistered User
underfloor heating for wooden floors*

There is a product on the market - from Qualpex if I remember rightly - which is specially designed for underfloor heating beneath wooden floors. 
Wood is not the best heat conductor - so to avoid patches of heat around the coils and patches of cold between the coils they suggest the use of "heat diffuser plates". These are thin strips of aluminium with a groove in the middle into which the heating coil is pressed. The strips of metal conduct the heat out from the heating coil. The metal strips are laid underneath the floorboards so that they press against the underside of the boards. This gives an even heat distribution even for wooden floors. Ideally they should be positioned on a layer of insulation - styrofoam for example- then heat goes only upwards into the room and not down to heat the foundations.
Worked well for us so far
Laoise

*BobtheBuilder
Unregistered User
Underfloor & floorboards*

As I posted elsewhere recently on this subject, there are 2 things to be aware of. If the heating is installed in a concrete floor, and you wish to have tiles on the floor, a special flexible adhesive must be used. If the floor is to be covered with boards, they must be good conductors and bad insulaters. Apparently the thermal properties for different types of wood varies. Sorry I cannot be more specific, but at least you can ask about that.

*gortfad
Registered User*
*Re: Under floor heating*

I am build my own house and I was considering putting underfloor heating in and I read a comment from a plumber in a building magazine that basically said that underfloor heating may suit Scandanavian countries but not Ireland with it's quickly changing climate. The fact that underfloor heating takes so long to heat up means that it takes a long time for it to cool down again which means that you have no real control over your heating system when the weather in this country can change two to three times a day. This is what put me off underfloor heating. I want an efficient heating system but I also want a comfortable house so I have decided that instead of putting in the underfloor heating I am going to use the money that I budgeted for the underfloor heating into insulating the house in the most efficient manner. 

*BobtheBuilder
Unregistered User
Underfloor & climate changes*

Hi gortfad,

You shouldn't skimp on insulation no matter what heating system you use, but anyway that's just stating the obvious. My main point is in regard to the speed with which you can adjust the underfloor heating to keep pace with outside changes. The system should have an outside temperature sensor connected which detects any changes and automatically adjusts the heat inside to compensate. Properly set, this should work better than "throwing another log on the fire" when you feel the chill (simplistic but I trust you get my point).
I contributed a few times on this subject and so should point out that I'm currently doing a self build which will have underfloor heating. Therefore I only know sketchy details as I haven't had time to look into it in great detail as yet. When I do, I'll post more details, because even though it's getting very popular, no one here seems able to contribute definitive details.

*Jim
Unregistered User*
*Problems*

Bback to my question, what if you have problems some time in the future, how do you fix them compared to your 'normal' radiators as i believe you won't have easy access to the pipes?

also i have a concrete floor with tiles over it (kitchen), building an extension shortly moving the kitchen so i will be pulling up the tiles and replace with either wooden flooring (my first choice) or carpet, my other question is how 'big' a job is to install under floor heating to an existing room? 

*BobtheBuilder
Unregistered User
Underfloor & burst pipes*

Hi Jim

The pipes used under the floor are meant to be high quality, durable, and tough. There are no joins, and all work is guaranteed. The system is pressure tested for leaks. What happens if your radiator pipe which is buried under the floor bursts? Anyway, most leaks in conventional systems are where joins/connectors are, so if you don't have that, then you have less risk of leaks.
Regarding putting it into a room, the floor would need to be kangoed out to lay the pipes and a new floor poured on top I guess. Not exactly a small disruption for your house! 

*Carlow
Unregistered User
Under floor heating*

Hi Jim

"what if you have problems some time in the future"

The same problem arrises with 'normal' radiators as the pipes are also under floor.

With the UFH it should be easier to isolate the leak by preasure testing each zone (one or more rooms) independently.
Also the rest of the house can operate as normal,
unlike the radiators.

Installing UFH
One method I have seen recently which seems ideal for one room is instead of laying pipes you lay cable.
Usually used in bathrooms for UFH.

*gortfad
Registered User
Re: Under floor heating*

Bob,

I agree that you shouldn't skimp on insulation but living to within your means is a good rule of thumb. 
The point that I was trying to make was that the responsiveness of underfloor heating is so slow that when your outside temperature guage tells the heater to start cooling it will take far to long to cool because of the sheer mass of the concrete floor. 

*BobtheBuilder
Unregistered User
Underfloor cooling*

True it takes longer to cool down, but this is seen as one of the upsides of this type of heating. Realistically, I don't see that being a major problem in Ireland! 

*Morbid Martin
Unregistered User
House Heating*

Your house is about 260 square metres I think.

Ive been told that unerfloor heating is only adequate (using existing density standards and boiler output) to a size of 150 square metres max. Any more than this will result in more expensive piping and boilers.

*BobtheBuilder
Unregistered User*

I'm building about 300sqm and have no special requirements regarding boiler size/special pipes etc. 

*JP
Unregistered User
Underfloor heating - suppliers ?*

I am organising a self build house in Wexford and am considering UFH, reading the above posts does anybody have positive/negative comments on the contractors/suppliers ? I have requested brochures from several 
SK services - [broken link removed]       
Devi - [broken link removed]     www.devi.com
Eurotech
Heat Link
Heatmerchants -[broken link removed]          
with the intention of reading up about the various systems and obtaining quotes but they all bascially say " we are the best" - what companies have posters used and who would they recommed ?
Also, for those who have UFH, what type of fuel/pump etc did you use ? I am currently looking at geothermal heat pumps - does anyone have experience of these? Would anyone have a heat source that they would recommend ? and why?
A UK website ebuild.co.uk/forums may be of interest to other self builders - anybody know of a similar Irish one ?

I look forward to your comments and help ! 

*heinbloed 
Unregistered User
underfloor heating for wooden floors*

I installed u.f.h. using heat diffuser plates,it works well,despite 20mm solid red deal .when using semi solid or other man made "timber" check for the " F1 "label concerning formaldehyde emissions .


----------



## WEST HAM

*Underfloor Heating*

Would anybody know roughly what the cost of running an underfloor system with a boiler is per annum, (oil costs), say 2,500 sq ft of a house. I have heard that underfloor uses a lot more oil than radiators, maybe that's all part of the insulation process, would appreciate a quick reply as I need to make my mind up with regards to which system to go with in a house I'm building.


----------



## sueellen

"heinbloed

I have installed underfloor heating and use a condensing boiler fueled with LPG . LPG is more expensive than oil but the system is so economic that I still use the first filling of the tank ( 1000l) despite it is used for cooking and warm water as well, I guess one fill will last for about 10-12 month "

Westham,

Does what heinbloed say above help in any way?


----------



## WEST HAM

*Underfloor Heating*

Thanks Sueellen, I really need somebody who is using oil to work out the  average cost, rough monthly cost would suffice. Thanks


----------



## heinbloed

*underfloorheating,oil or gas?*

You could use the heat comparrisson sheets of
ww.sei.ie./documents/uplo...lications/
Domestic_April_2004.pdf
It gives you a handy method to compare like with like.


----------



## heinbloed

*heat pumps*

In some earlyer  posts the question occurred if it is worth it to go for heat pumps as a source of heating(the under floor heating system or conventional).My answer was NO because it would be to expensive with electricity to run the system,the only ones available here.Elderdog had mentioned gas driven heat pumps and I searched the web,we both knew they exist but had no knowledge about who would sell them.Here are some results:
The major company  selling them seems to be SANYO,the Japanese giant in electrics.I am sure anyone interested in these heat pumps is able to contact SANYO via the web/e-mail,sorry I have no URL.
In Italy   www.robur.it
In Germany www.kaut.de
                [broken link removed]
                [broken link removed]
                [broken link removed]
www.stulz.de
www.schmitt-mayen.de
These companies produce gas driven heat pumps from the small 14kw unit up to the 10,000s kw so plenty of choice for the household and the business.It seems to be the case that in economies with a free market gas fueled heat pumps are 50% cheaper to run than electricity fueled ones.
The list above is by far not complete.I just picked the ones that came up first.


----------



## JP Saltee

*Re: Underfloor heating*

I have just started a new build and would like underfloor heating. having read entries in this post and similar I still have a few queries, in particular I think that MOB, heinbloed, Alpha or Bobthebuilder may be able to help me- or anyone else!! 
How long did the system take to install? In particular in relation to the plumbing, laying of pipework ie all the work that has to be done in the foundations before the block/timber frame can be constructed on top? I have a very tight time frame in which to build.
 In obtaining quotes (I have 3) are there any particular items i should ask for/query in addition to the companies standard?
Has anyone used flooring material other than wood or tiles - what and how has it performed?
My living/ dining roon is 4800x8000 and double height and almost completly glass on 2 sides including gable end - in your experience what would be the best method of heating this room? would u/f be apprioate?
Polytherm is the company I am thinking about using - alpha or anyone who has used them- how did you find their product? any problems? any hidden extras? anything extra I should ask for?

thanks in advance for any help !!!!!


----------



## heinbloed1

*underfloor heating*

Hi JP Saltee!
You can install the underfloor heating systems after the window installers are gone , you don't  have to put it in place before the walls,roof, doors and windows are in place.
You have a quiet voluminous space to heat,so underfloor heating is the right choice.But keep in mind that the volume of the room can cause drafts,so make sure you get the best doors and windows (not necessarily the most expensive) to make it draft proof and , of course, the best insulating panes you can afford.
I constructed mine myself (96 m2),timber floor on timber beams using 13-15 cm insulation between the beams.Including the installation of the floor the entire job took me less than four weeks,so if you have a crew of 4 trained installers it would be less than a week.A two men team would be ideal.
Since you have 2 high glass walls you should consider to have two openings at the top,either thermo controlled or manual, for aeration purpose.A high room can get very warm and not always it is possible to aerate via the doors.


----------



## JP Saltee

*Re: underfloor heating*

thanks Heinbloed!

a couple of further queries...
You say " you "can install u/f heating after window installers are gone" I thought that in the case of a new build the optimum time to install u/f heating is at foundation level as it is very messy job afterwards and difficult to get a smooth screed?? and every company i have spoken to say there could be problems/hassle if installed after. when did you install your system?
In my large living/ dining room i intend to have double glazing filled with argon,and well sealed doors and windows also this room will have an open fire (blocked up when not in use). However i also intend to have wooden flooring, for a few years this will be laminate as the house will be summer let (pay the mortage!) and then i would like to replace with solid wood when for my own use. what provision should i make at this stage????. As far as i understand i will be laying sub floor then insulation (think upgrading from min 50mm to 80mm high density TF70 kingspan) with u/f piping on top with concrete screed over. should i install battens in the screed from insulation layer to top of screed? this obviously would provide a means to attach solid timber at later date (once left in room to combat shrinking/expansion etc) but how does it effect heat transfer? does it help in any way? also some companies say the solid timber can be simply floated on the screed ??! I can imagine this is what is done with laminates but does it work for soild wood?
also, have you laid carpet? am trying to decide between carpet or wood for bedrooms......
Thanks for all help !!!


----------



## heinbloed1

*ufh*

High JP Saltee!
The ideal situation to lay an UFH system in screed is when the doors and windows are in.Reason:The system needs to be pressure tested (the boiler as well)and the water in it could freeze(which should be no problem in summer).The second reason is that the screed could crack if exposed fresh to high air exchange and sun light.Windows can be closed and shaded if necessary.
After about two weeks of drying the screed the floor tiles can be put in place,the ideal method to glue them is a cement based mortar,if necessary a primer might be useful.The chemical glue would be "combed" on to the screed leaving air pockets between the tiles and the screed which in turn is neither good for a perfect heat transmission nor is it advisable due to shrinking.  
Putting timber flooring-laminate or solid- on an underfloor heating that is already in a screed gives not only a high fuel bill due to the necessary increase in flow temperature , the screed might even crack if exposed to a to high temperature in the coils.
If you still have the choice than put some 10-20 cm of high density PS sheets under the building,before the ground slab is casted. 
Check the home page of the company Aeroboard,as far as I remember they show how it works.
If you go for insulation ON the slab-followed by the UFH-than go for at least 10cm,better 15cm.The standard 50mm advised by the manufacturers of UFH are not enough in my eyes,they want to show picture that looks attractive in terms of investment.more insulation on the slab means additional height of the rooms.e. higher costs. I think the building regulations  demand this 50mm amount of insulation in buildings anyhow without UFH,so you are better off going for some extra.On the continent where they have the same soil temperature as we they use about 20cm under the slab and 10cm min. under the screed.
Insulation is a once off investment,it won't be used up like oil or gas,it stays for ever with the building saving  money as long as the building stands.And it is cheap.
The better way to install a timber floor on underfloor heating is to use heat deflector sheets which are placed on insulation sheets.These are strips of alumina with a dent  in the center lengthwise .This dent will take the pipe and diffuses the heat over a larger surface.Check the home page of the company Qualpex,they show how it works.
Putting the pipe in screed AND covering with timber-which is a good insulator in it self!-would make the reaction time of the UFH very slow and the output very small.For the same reason the floor should not be covered with rugs or carpets.
Don't think about "floating" solid timber on an underfloor heating screed.Timber always "works",even on an ordinary cold screed solid timber should be fixed.Timber takes up moisture and expands when it is heated up , it will shrink when cooling down.The planks buckle and twist if not securely fixed. This effect won't be as bad if using artificial "timber" flooring,but also there it would be wise to fix it to the screed or on some battens.
Carpet or wood?Well,with UFH carpet is out of question,but some manufacturers of carpet flooring claim that they have also products for UFH.A natural timber floor always feels warmer on the feet than a cement or tile or PVC flooring.And it is free of hazardous chemicals that could come out when the heat is turned on.
When going for timber on UFH heating make sure the timber had been kiln dried ,that would take out some of the formaldehyde naturally occurring  for example in spruce or pine.And try to source it as dry as possible.


----------



## kfpg1

*Re: ufh*

Some questions for Heinbloed

1.Does an UFH system not have some kind of antifreeze agent in it?
2.What would the primer achieve prior to a cement based mortar when laying tiles. What is the primer material?
3.You don't suggest any alternative to 'combing' out the chemical glue prior to tiling which causes air pockets and shrinking. Do you suggest simply not to comb it and float it out smoothly?
4.You speak of putting 100 to 150mm insulation under UFH. In practicality the vast majority of people can't do this, (yes it makes rooms higher - buildings taller - costs more - and takes great foresight which the average self builder wont have the knowledge for) but shouldn't you point out that the quality of insulation is not only related to its thickness. It is possible that for example a 65mm board with an efficient U value rating will provide better insulation that 100mm of aeroboard insulation with a poor U value rating ?


----------



## JP Saltee

*Underfloor Heating*

thanks again heinbloed !

the system will be pressure tested but with air, this "testing" will be on while the screed is being poured so that any breaks will become noticable as air bubbles in the screed. No water will be in the system until boiler is connected. In my case i dont think the screed will really have any time to be exposed as the day it sets the walls are starting and as soon as they are finished the roof starts - I can cover with taurpaulin anyway. 

The make up of the floor is a follows; hardcore, blinding, radon barrier & dpc,sub floor 4-5 inches, insulation 80mm of Kingspan high density polyurathane (i believe this is equla to 160mm polystyrene) u/f heating pipework with screed of 75mm on top - then flooring! 

the heat deflector sheets seem to be unique to Qualpex, and speaking to them they only mentioned the sheets in relation to 1st floor level and screed for the ground floor! Every company and every person seems to suggest different methods for wooden floors: battens sunk in the screed to afix the wood OR floating the wood on top of corraguated cardboard OR glueing the wood to the concrete screed......so confusing! Really at this stage i need to decided whether or not to sink battens in screed. I'm starting to ask myself is u/f heating worth the hassle???


----------



## heinbloed1

*ufh*

Hi kfpg1!
1.) No,an UFH system needs no antifreeze.If it was suspected that frost could reach the pipework than the pipework would have been badly installed-not insulated for example.May be you mixed up the Under Floor Heating which is installed in the house to give off heat
with the Geothermal Heating System which is installed under the ground outside of the house to collect energy.
2.)A primer prior to setting the floor tiles is not always necessary.But in cases where the screed is crumbly i.e.dusty it is.
3.)The alternative to combing the glue is indeed to set the tiles in a "bed"of cement based glue,also called "floating".Especially with the UFH system it is advisable,but also when using wall heating systems for example.
4.)The quality of thermal insulation depends not on its thickness but usually  on its air content(there is  also new vacuum sheet on the market but that is still not available to most of us).A high density PU foam has less 
insulation(U-) value than a low density one from the same material,the same counts for Expanded Poly Styrene (EPS,Aeroboaerd).The high density material is used in UFH for its structural stability-you don't want to see the piano or the partition wall sink into the floor because the insulation "gives".
Now the best insulation material for UFH -well insulating but thin -is expanded glass foam.It comes in sheets about the size of aeroboard and it is Grey/black and quiet heavy,that would add to sound proof if necessary.But I have not seen it available in Ireland.
Polystyrene foam sheets come in different qualities,most manufacturers can provide you with suitable material to substitute the more expensive polyurethane sheets.
Demand the technical data sheet,it will tell you and your builder about U-values and structural properties like load bearing capacity.

To Jp Saltee !
The pressure test should not be relied on "bubbles in the screed".This method would not cover pipework going through walls or ceilings.A correct pressure test is done by applying some pressure and measuring it.Than a certain time has to pass-usually 24 hours-whilst the pressure is kept and than the number on the meter should still be the same as on day one.A builder that would cast concrete on an evtl.leaking pipe is a cowboy.What would he do if he really discovers bubbles?!Throwing out the entire screed before it sticks,damaging the pipework incl.the fixing battens and the insulation material with the aid of shovels and picks? Get a plumber in who will do a properly documented test,he will give you a "certificate of compliance ".If you get in trouble with your heating you can go back to the builder or claim money from your insurance or make the manufacturer liable.Your position would be better with some documentation.
And it is not expensive ,a job of a few minutes. 
Don't sink battens into the screed to fix timber flooring on them.The entire construction would be to slow reacting,to cold to heat up the room.The heating pipes must touch the timber directly,timber is a to good insulator to loose out even more on warming up the screed.Qualpex is not the only manufacturer to use the heat deflector sheets,Unipipe has them ,others as well.The reason why they are not frequently used here is the extra cost involved for labour and material.
Each manufacturer from whom you buy the material will give you a free quotation on what you need.But you have to provide them with some facts,for example which flow temperature is the boiler providing.The flow temperature for a well insulated floor(the one covered in timber on top of the screed)must be higher than the flow temperature in the room without the timber floor.But your boiler has to provide it.If you need in one room a flow temperature of lets say 45 degrees and in the other room 35 degrees than the boiler has to burn a lot of fuel extra for these ten degrees.Further on you have to install mixing valves to supply the "colder" floor with colder flow water.This involves extra plumbing,additional risks of leakages and certainly extra costs. A 35 degrees system could be fed with geothermal heat or solar power at least for some of the time  ,a 45 degrees system would need additional power to that.Since the UFH system will last for 50 years or more a builder should consider the increase of fuel costs and the consequences to the building being constructed.The strength of an UFH system lies in its ability to run on low temperature and to be maintenance free.Make the most of it.We could face a tripling of fuel prices  within a few years and solar panels will become cheaper.With a well designed heating and insulation system you are well prepared for the future.But if you need 45 degrees in the floor heating loop then why going for floor heating at all,a well insulated building could be heated with radiators running on the same temperature reacting faster and being more economical to install.


----------



## kfpg1

*Re: ufh*

Heinbloed - for clarification purposes

1. New vacuum sheet = good insulation = not available
2. Expanded glass foam sheets = good insulation = not available
3. High Density PU foam / EPS / Aeroboard = strong but not good U value
4. Lower Density PU foam / EPS / Aeroboard = better U value not as strong
(what is PU ?)

In my situation
a.committed to installing underfloor heating on top of concrete raft downstairs and concrete hollowcore upstairs
b.planning to use as much tile as possible in house but with some timber flooring
c. with 150mm available from top of raft to bottom of doors

what approach to insulation materials & thicknesses / screed depths / floor fixing methods would you recommend?


----------



## heinbloed1

*ufh*

Hi kfpg1!
PU stands for Polyurethane,the yellow insulation sheets.
With the specification of your ufh you better stick to the drawings of your engineer/manufacturer.All you have to ask them if there is a method to increase its efficiency or comfort.This could mean increased insulation (may be combined with a thinner screed).When installing the insulation sheets use two layers instead of one,you will have less gaps going all the way through.


----------



## sueellen

*Some other posts*

*Lilly
Unregistered User
Under floor electric heating?*

was wondering what people thought of this option and whether they felt it was economical in the long run.

I am slowly doing up a 12 year old apartment which currently has basic electric heaters which need upgrading. Gas is not in the area, so I am stuck with electricity as the heating source. Am thinking of putting it under tiles in the bathroom and under carpet in the bedroom. The alternative is to replace the existing electric heaters.

Any thoughts would be much appreciated..... 

*Bob
Unregistered User
underfloor heating*

I would advice you to stear clear of underfloor heating whether electric or water.
Depending on the lay out etc. of your apartment I would advise you do go for oil fired cnetral heating, all the pipe work can be run on surface i.e. run along skirting boards etc.
You have an option of indoor or outdoor boiler - a good brand name is Firebird. The outdoor one is about the size of a large dustbin no need for chimmney flue etc.
You will find that's it's the most economical in the long run and you will have gallons of hot water for domestic use. It can be set to heat domestic water only for summer use but be sure to fit a good copper cylinder for this purpose. 

*davelerave
Frequent poster
Re: underfloor heating*

i'd advise keep it simple for renovation.go for oil-fired with outdoor boiler or maybe replace the heaters if it's all wired up properly for night storage 

*heinbloed
electrical underfloor..*

I am afraid you have not many options unless your apartment has a chimney.Apartments build with electrical heating systems have been build using the cheapest method for the builder(initial costs) to leave the owner facing the bill on the long term.
There are only a few methods of heating an apartment that has no chimney or central heating system.
Electrical underfloor heating is one method,but again-cheap to install and expensive to run.
Something else would be bottled gas feeding a condensing boiler(room sealed system) that would heat up radiators.There are also small oil-fired condensing boilers available which have a very small tank that would hold enough oil for a month or so -ca.200l-in a tank the size of a cupboard fitting into the kitchen unit.The manufacturers claim that there is no smell of them.
(On the continent they even have boilers that run on methylated alcohol/ethanol.)
The problem with both of these combustion systems is a.)the installation costs and
b.)the limited fuel storage capacity-and therefore the purchasing price for the fuel
If you have any chance to convince the other apartment owners -maybe via the management-than you should opt for a central heating system supporting the entire building .It will certainly pay in the long term.
I am sorry I have no better news.

*sherman
Registered User
Re: electrical underfloor..*

I have electric underfloor heating in my rented apt. and was stunned when I got my first full ESB bill - it is an extremely expensive way to heat anything but a very small area. Avoid if you can... 

*askew70
Registered User
Question re DEVI underfloor electrical heating mats*

I have read through this thread, and those linked to above, with interest, but I haven't seen much mention of the specific option that we are looking at at the moment. We are considering laying DEVI electrical underfloor heating mats under new floor tiles in our kitchen, and would appreciate any observations of those that are familiar with this particular (type of) product. The kitchen has concrete floors, and is north-facing. Right now there is one radiator in the kitchen which is just about adequate most of the time and more than adequate when the room is warm from cooking. We are looking at 12 sq. metres of DEVI heating mats.

We plan to replace the existing cork tiles on the floor with ceramic tiles, but wondered whether this might reduce the overall temperature of the room, hence the interest in the DEVI product. Does anyone know whether ceramic floor tiles, laid on a concrete floor in a north-facing room, are likely to have a cooling effect on the room? And if so, are the DEVI mats worth considering?

The DEVI marketing blurb is, obviously, enthusiastic about the effectiveness and economy of their product, but someone suggested to us that it is likely to be inefficient as there will be nothing to store the heat given out by the mats so the heat will "disappear" once the mats are powered off - which could make for a useful source of "instant" heat but would not be very economical in the long run.

Thanks for any advice or opinions.

*heinbloed
DEVI*

First of all:I have no experience with DEVI underfloor heating mats.
Think about insulation below the mats before you install them,with any underfloor heating system this is a must.
Most manufacturers recommend at least 50 mm of the better insulating material,if installing underfloor heating on the ground floor than at least 100mm is necessary provided there is no basement/cellar or already some form of insulation in place.
From your description I think a larger radiator-maybe a double or triple shell type- or a second one may be the better solution.Place radiators under the window where possible.
Electricity is the most expensive and polluting form of heating energy,see Irish Energy Center.
Ceramic tiles as such have no cooling or heating effect,they take up and release the temperature to which they are exposed to.But they feel colder to the touch compared to cork tiles. 

*askew70
Registered User
Re: DEVI*

Thanks a lot heinbloed. Your advice has helped us to finally decide against installing the DEVI mats. I hadn't thought of the environmental impact of using electricity as a source of energy, but even if I had, we have a fitted kitchen in place which would make the installation of 100mm of floor insulation impractical. If we find heat to be an issue after the tiles are laid then, as you suggest, we will consider installing a second radiator or a bigger radiator.


----------



## Builder

*Re: >>Underfloor Heating*

Is it possible to have underfloor heating under carpet, I had hoped to carpet one or two rooms and the remaining rooms would either be timber or tiles.

Anybody used Nu-therm, Co. Donegal, or Warmfloor Heating Ireland in Omagh, i have asked these for quotes but would like to hear from people that used them for UFH or Geothermal Heat Pumps.

Heard a story about Geo Heat Pumps where somebody received their ESB bill and it was about €4000 for 2 months because some switch was in the wrong place so I would be weary about this!


----------



## z102

*Re: >>Underfloor Heating*

No. Carpet on an under floor heating is no way to heat a room efficiently . And that is the aim of an UFH. It would insulate your floor in the wrong place . Try to heat your room with a radiator wrapped in carpet. Some carpet manufacturers claim to have the carpet for UFH - I haven't seen it working yet .

About the geothermal pumps check  the other posts. Check out as well the home page of the IEA -that is the international energy agency . And you will find out that these things called geothermal pumps here in Ireland aren't the real thing. Just a sales gimmic to fool the inexperienced buyer. See  http://www.iea.org/

A geothermal heat pump draws the heat stored in the planet . What they sell here are slow reacting over dimensioned expensive solar collectors .Exploited by the means of a heat pump . They make your land useless for any further development . Be it an extension or a sewer , an arboretum or a swimming pool. The space is lost , except for a lawn maybe . Take the costs of the land into your calculations as well . And you have to put them on the south side of your house because of shading . No trees and buildings in their vicinity.


----------



## yop

*Re: >>Underfloor Heating*

Out of interest Heinbloed if the heatpumps which are been imported are european and are used in Europe how are they different.
The reason I ask is that on the majority of cases that I have seen for Geo the heatpumps are coming in from the continent directly, are you saying that they are changing the heatpumps here in some way? do you have any evidence of this?

Taking the costs of the land into consideration is a bit of a broad statement, you own the land and it is not a case in the majority of cases that you will build on 100% of your site, therefore there will be vacant land and you own it anyway, it is not a case of buying a site for the exact size of your house.

What are the difference between the heatpumps in Europe and the heatpumps here?


----------



## z102

*Re: >>Underfloor Heating*

. Heat pumps are heat pumps. Technically spoken . But here in Ireland the technical knowledge of the would -be- costumer allows for some nice looking additives . For example the term " geothermal heat pump ". 

The term " geothermal " is strictly reserved to heat from the ground . In the scientific/technical world this is heat stored in the crust/body of the planet  earth .

Here in Ireland they use this term in any case for any heat collected from the ground . Which is technically wrong. But who minds ? Somewhere else competitors and consumer organisations would have coursed and brought the culprit to court...

Heat that is derived from the sun is called solar energy. Nothing else .So a flat shallow heat exchanger dug into the ground makes use of the stored solar energy . Once this is exhausted it has to switch off and wait for a few warm month to warm up the media , the soil . Not so the geothermal energy exploiting system. Be it a heat pump extracting the heat  or a direct fed hot brine/water system , lets say a hot spring in that case . There are entire nations depending on geothermal heat pumps , Iceland for example .

A real geothermal system needs no sun to get warm . That is the difference . If you had a real geothermal heat pump installed in your back garden than the points I made above ( shading etc. ) would not bother the efficiency of the system . Just a borehole  delivering heat   for decades . That's the difference .

Always include all costs . Also the cost for court cases against your neighbors who's trees and buildings are causing shading , who's wells and foundations might influence the efficiency of a so called  " geothermal heat system " .And also the costs of plan B . When you can't forbid your neighbors casting shade on your property .

A solar panel/tubes will be much more versatile. If the panel is not good in one place than bring it to another . A few meters of extra pipe laid in an afternoon. No court cases , no trees to be chopped. Peace . And if you move than take the panel/the tubes with you . No problem .Try this with one of these so called ....digger employment schemes ?


----------



## Builder

*Re: >>Underfloor Heating*

Re insulation for UFH, SEI has advised me that instead of increasing say the insulation on the ground that it would be of better value to increase the insulation in the roof, as heat rises.

re screed.  Has anyone used easy screed or a similar product for over UFH.  It uses only 35mm screed instead of the normal 75mm.  I was advised that using 35mm will allow the temp to be controlled more.  Also any idea of cost, would it be more expensive than the normal 75mm screed.

Is 6'' space between subfloor and finished floor sufficient when installing UFH and using say 60mm insulation.  Will use 20mm floor boards.


----------



## babydays

*Re: >>Underfloor Heating*

thinking of underfloor heating in my kitchen (under timber or laminate). I know lots of details would be required for a more accurate guestimate but would anyone be able to give me a v. v. rough estimate of cost for area of 4.5 X 3.5 meters?


----------



## kfpg

*Users of underfloor heating: what settings?*

This one goes out to anyone who is experienced in using UFH in their homes.
Basically I am trying to get the most fuel efficient usage of the system from all of the adjustments that can be made. What do people out there generally do regarding the following?

Room Thermostat Controls (digital in my case)
Leave at 18 to 20 degree range ? - use time profiles to have slightly warmer morning and evening during occupancy and cooler during night and working day ?

Supply or Flow Temperature Coming from Boiler to Manifold
I can set this to whatever I want - is 45 degrees enough?
If I go higher or lower does this just increase / decrease the rate at which rooms warm up? i.e. responsiveness. If I go too low on supply temp does the system struggle in some other way

Taps at the Manifold for each Individual Pipe Loop
What do people do with these again isn't this about responsiveness e.g. fully open = faster heat. If so aren't these and the supply temp above giving similar control?

What's the best balance for all 3?
(I appreciate homes are different in terms of insulation and personal tastes differ BUT what works for you especially re:fuel economy)


----------



## Sherman

*Re: Users of Underfloor Heating: What Settings?*

During the working day (assuming you're not there) you can/should turn it right down (I think the recommendation on the UFH in my previous place was 10c, although I used to just turn it right off) rather than leave it at 18-20c. No point heating an empty house!

I don't know about others, but I found UFH to be very expensive.


----------



## z102

*Re: Users of Underfloor Heating: What Settings?*

My own experience differs miles from Sherman's. Cooling your house by setting the flow temperature to 10 degrees - why ? 

First point : What sort of UFH have you installed ? 
Second point : What flow temperatures does your boiler allow for ?
Third point -and propably most important : Is the system adjusted ? At the manifolds - there are two of them (flow and return ) - you will find little "meters" showing the rate of  flow in liters per minute .At these little gadgets your heating economy depends on . When having all circuits working for let's say an hour or so then the temperature of the " return water " at each of them (meassured at the return manifold ) should be the same -no matter how big or small the individual heating zone is .You can meassure the temperature at these  "return manifold inlets " ( I don't know of any better expression, hope you understand ) with a thermometer. Either a simple outside/inside thermometer where you place the outside probe with the aid of some cellular tape directly to the relevant brass joint or with a more sophisticated laser thermometer as used for example in the food industry .The process is called " hydraulic adjustment " .
As long as these temperatures are equal your system is set at the best point . For economical reasons it generally should run at the lowest possible flow temperature.You won't save money by switching it off at night time , the opposite might be the case. At least not in winter. Some boilers allow for a "reduced night time temperature" which you can set your self at the timer .If your UFH is the standard concrete floor than this might not be necessary , depending on the quality of the concrete and the covering . The slower it reacts the less sense it makes to adjust the flow temperature for different times. 
When going for a fully automatised system an outside sensor with memory would be " the dot on the i " - making the system fool proof .These sensors are new to the Irish market , check your boiler manufacturer if they can be retrofitted. Usually that is the case with most boilers , but it might take ages to justify the extra expenses . But with the increasing fuel prices in mind you never know- money saved today might cost twice as much tomorrow to save it .With a (home) sellers point of view go for it .As a home occupier - I don't know.


----------



## feorais

*Re: Users of Underfloor Heating: What Settings?*

I use UFH for 2.5 hrs in the winter per day.I use 850 lts a year in an 1800 sq. ft house.I have extra insulation throughout, particularly walls and roof,paid for itself in two years. Re thermostats in each room: Keep unused Bedrooms set at 16 degrees.used bedroms at 18D,Hall at 18D,Living areas in general at 21 or 22 D. Only turn on heating at, say, 16.00hrs. for the no. of hours you require to have the living areas comfortable, particularly at night.(in my case this is 2.5 hrs.), as the heat is held in the floors etc and is slowly releasing same until heating is turned on again. In this country you do not need an external heat controller.Have main control valve set at 50 degrees, does not need to be adjusted.In the rooms where there is no usage,the 16 D is ample once you keep their doors closed.Some obvious but much disregarded guidelines:Eliminate all draughts. Keep external doors closed at all times(also windows closed except where necessary to have open, say in a bedroom at night)Always pull the curtains in all rooms as soon as practicable each evening. Check attic insulation again! Is there at least 10 inches of well fitted fibre glass in place?A more drastic step can be taken to improve overall insulation (where only the cavity wall "insulation" was installed originally, is to retro install an inside layer of polyurethane backed insulation board, with the plasterboard finish facing into the rooms (8 ft x 4 ft.sheets). These can be skimmed and plastered where necessary and are really the answer to poorly insulated buildings. It makes sense to have your insulation in the room rather than allowing any heat in the house to evaporate through concrete walls where poorly fitted polystrene is supposed to stop the heat from getting any further. It simply does not work no matter how well the builder tried to do a good job, and how many times does that happen? Hope this helps you in some way.


----------



## niceone

*Re: Users of Underfloor Heating: What Settings?*

Whatever you do, underfloor heating is EXPENSIVE !! We have an oiled fired Boiler and the house is 2650 Sq Ft. We have 6 zones on the ground floor and radiators upstairs.  2 zones are very rarely used and I have them set to 10 Degrees all year round.  The other zones I set to between 18 and 20 Degrees from October through to April, I then turn them down to 10 purely to save money !

I just leave them at the set temperature. If you switch off in the morning and switch back on in the evening, the floor slab will eventually cool and you'll spend more money reheating it.  In theory the most efficient way is to leave at the set temperature and UFH will kick in and out as required.

One of the problems is that if you leave your door open for even a few seconds, the cold air triggers the thermostat and off you burning oil again, same for windows.

If I could do it all again I would not install UFH !!  We're burning approximately 3K / 4K Liters from Oct to Apr.

An interesting product that is supposed to cut costs is Oxyvent, see http://www.oxyvent.com/ for details.  It claims big savings by removing air bubbles, allowing water to return to the boiler much quicker, therefore losing less heat and requiring less reheating !


----------



## Carpenter

*Re: Users of Underfloor Heating: What Settings?*

http://www.oxyvent.com/ 

Does anyone have any experience of the Cremin Oxyvent?  I've heard a lot about it but I don't know of anyone who has it installed.


----------



## niceone

*Re: Users of Underfloor Heating: What Settings?*

Spoke with Tim Cremin (MD of Oxyvent) he gave me 2 referalls.  They swore by it.  One guy was a Garda who also found he was burning oil big time, now he's not.  I'm considering installing but price is putting me off, I reckoned about €1,500 !!  One guy at work installed for an old radiator system in his house, his radiators never heated up properly, now they're hopping !  And he's a genuine legit guy !!


----------



## kfpg

*Re: Users of Underfloor Heating: What Settings?*

Heinbloed - some clarifications
UFH = standard water filled pipe in screed above insulation.
Flow temp I can set to whatever I want digitally - I also have the outside air sensor.
I am most interested in the manifold adjustments. On the flow side of each loop there is a dial which is essentially a tap which as you say would adjust the litres per minute rate of flow. Each dial has a setting from 1 to 10 ( I dont assume its 1 to 10 litres?) I guess 10 = fully open. 
The part of your comment I don't agree or follow is that the return temp of each loop should be the sames as the flow. Surely temperature is reduced in the return node because energy in the form of heat has been transferred from the water via the pipe, the concrete and floor covering to the room. Therefore the return temp could not be the same. I guess the lower the temp drop the more efficient your system is and probably a result of how well your system is designed vis a vis insulation below screed etc. In my early experience of running the system I see an 8 to 10 degree drop between flow and return - do you think it should be better? (I know this from a temp dial on the flow versus a temp dial on the return - although this is one dial for all the flow pipes and one for all the return pipes not individual measurment of each flow / return loop if you know what i mean )

To reduce the differential do I open or close the valve on each loop.
Open valve = faster flow - higher demand on the boiler - higher fuel use
Close valve = slower flow - lower boiler demand & fuel use

How does one judge if setting 3,4 or 5 etc is best for efficiency. My guess is that if you opt for an always on system (i.e maintaining constant 18/19'C) then heating response / reaction time becoms mostly irrelevant and the tap should be almost fully closed on each loop - do you agree?

Guys - on the Cremin tank i checked it out and saw the merits in principal but didnt do it re cost / complication etc. I think in my plumbing sytem I have vents which expel air anyway.....


----------



## z102

*Re: Users of Underfloor Heating: What Settings?*

Hi Lakeview !

The temperature at the RETURN , measured on the brass junction at the end each of the loop ( where they join the return manifold ) should be the same . Not the same as where they start at the flow manifold , that is logical as you have said . The temperature gets less when passing through the loops , of course . 
The flow adjustment meters give indeed the number of liters per minute. The heating suplier/installer should have made a calculation sheet where the settings of these gadgets should be stated . But this calculation is never as correct as a meassurement done in vitro. During building the UFH a loop in a zone might not fit in or an extra one is put in because the fitters/installers find that there is plenty of room to do so - or not . The real site differs often from what is on the drawing . Also heat gains from the sun and ocupants behaviour (doors , windows opening i.e air exchange from cold droughts etc. ) can be of influence . So measure it .
As you said the flow and return temp.difference ( meassured at the boiler )should be around 8 degrees . To increase the efficiency of your boiler it is the best to have this difference gap as large as possible . BUT : and this is important : A difference to big could cause the screed to give off sqeeking sounds due to the higher expansion differences .It might even cause cracking , but that would be more the case with temperature differences of around 50 degrees depending on the concrete screed , hardly the case in a standard working UFH.
Back to the setting of the hydraulic pressure.
Each loop opens by the " demand sign " coming from the room sensor . 
So the warm water can get in . But on deciding how long it stays there the flow reducer comes in . It allowes for the correct setting so the return temperature is the same for  all zones . 
Zones pipes have different sizes . Some are fully 150 meters long , some are just 30 meters long . 
So sending IN the same temperature would result in different temperatures coming OUT . This shouldn't happen . 
To adjust this dilemma the " standard " for adjusting  is the largest i.e. the longest pipe . This is not necessary the one  from the biggest zone , it could also be an average sized zone but in a far away place in the house . The lenght of the pipe decides .
When you have found this pipe you turn the reducer fully open by turning its base , not the looking glass itself   . To make as much warm water passing through the zone as possible .The little float in the reducer shows how many liters are flowing through the pipe . Read always at the lowest point of the little floating ball .  
Then you go to next longest pipe . Measure the temperature at the return as described above .  If it shows a larger temperature as the first one then you close the return valve ( the thing with l/min. on it with the float in it  ) by turning it's base until the temperature is equal to the one you have done first . 
Then you go to the third longest pipe . Again the same story . Reduce the liters per minute that pass trough the zone untill the return temperature at this zone is similar to the two return temperatures you have meassured before . 
And so on untill you have reached the return of the smallest zone/shortest pipe. 
All return temperatures should be the same . 
Job done . 
Note : When adjusting the liters per minute then you will realise that the temperature and the flow rate ( the little ball will go up ) at the first return will increase more and more the more you " close " the other zones . That is fully normal. Nothing to worry about . The explanation is easy : The pump has only a certain capacity . The longer the individual pipe is the longer it takes for the warm water to pass through . And the water will flow faster when you close or reduce the flow of the other zones . So the longer the warm water takes to " get through " the colder it will arrive at the return manifold . And when closing /reducing the flow per minute of the other zones the more pressure  (created by the pump )  will push the warm water faster through the one . 
In easy words : The pressure has to be shared by the zones . The less the one gets the more the others get . 
And the faster the warm water rushes through a pipe the warmer it will be at the outlet . 
The fuel use of your boiler depends on the heat loss of the heating pipes/zones/radiators   . Not in principal on the flow rate . If the boiler senses cold water coming back it fires . It does not sense the flow rate resp. it won't react to it .
In more advanced modulating boilers the pump in combination with the outside sensor will react , like an artificial intelligence the different parts communicate to give an optimum .But even at more modern boilers the pump quiet often is only fix set manually at differnt stages I,II and III . It depends on the minimum output of your boiler and on the minimum demand of your heating where to set it . In theory it should pump fast enough so the boiler does not overheat . A modern boiler has several features to prevent overheating , it simply shuts off the firing sequence until it has cooled down again . 
When realising a " ping-pong " or "on - and - off " firing then the pump is not pumping fast enough or the difference between flow and return temperature is not set far enough apart . You could give it a try by setting the flow temperature at lets say 35 degrees and  the return temperature at 36 degrees . Just to learn from it , not to run it in a standard mode ! The boiler would switch on and off , making it very uneconomical since during the start firing since it uses compareable much more fuel during the start frequence as during the modulated run .   
Hey, when we are finished you are plumber ! 
Good luck !      
 The hydraulic adjustment as described above goes for any heating system , UFH  or radiators .Every plumber should be able to do that , but most aren't . Many never heard about it .


----------



## kfpg

*Re: Users of Underfloor Heating: What Settings?*

Heinbloed - that is possibly the best and most detailed response I could have imagined - much appreciated. Unfortunately I suspect that for all the people who chose UFH for comfort and economy the vast majority have not performed this kind of exercise and consequently have an underperforming system. 

The only part I am unclear about is;


			
				heinbloed said:
			
		

> As you said the flow and return temp.difference ( meassured at the boiler )should be around 8 degrees . To increase the efficiency of your boiler it is the best to have this difference gap as large as possible . BUT : and this is important : A difference to big could cause the screed to give off sqeeking sounds due to the higher expansion differences .It might even cause cracking , but that would be more the case with temperature differences of around 50 degrees depending on the concrete screed , hardly the case in a standard working UFH.


 
My understanding was that water only flows in the loop when a room stat calls for heat, when the room is at the desired temp then the flow valve shuts. If that is the case then when water flows in order to heat up the room if it returns at a significantly lower temperature then surely it means a lot of heat energy was consumed in transfer from pipe into floor screed. In other words had not the screed been allowed to cool too much ! if it required a large amount of energy to re -heat it. That would go against the principle of more constant and even level of heating and perhaps suggest an unresponsive system in terms of when the room stats see the need to call for heat ??

BTW - I dont have a device on the manifold with a floating ball - just one adjustable dial on the flow side of each loop only.


----------



## z102

*Re: Users of Underfloor Heating: What Settings?*

Thanks . About the temperature difference "measured at the boiler " and the efficiency of it : I was talking/writing  about the efficiency of the boiler only , not about the efficiency of the entire heating system .The boiler is only part of it , pump and manifolds, pipes and radiant surface are belonging to it as well.
So to run the entire UFH system on an efficient modus your system setting of 8 degrees flow/return difference is absolutly fine . 
You are right about the reheating of a cold screed . For the efficiency of the heating system - and for comfort - this would be not desireable . The boiler would be working efficient but not  the system as such . Compare it with motoring. Instead of wasting  time in a bus one could take the private car and push down the pedal to get from A to B . That would make the private car in this case ( time-) efficient . But it certainly would not make the journey fuel efficient .
The boiler would work most efficiently when starting to fire and then puting out as much energy as wanted in one go - measured in kW . But having a hot floor for a few hours and the rest of the day a cold floor is not what an UFH is supposed to do .So spreading the kWs over the entire demand period of a day and tolerating some loss ( because of repeated boiler starting frequences ) is the way an UFH becomes effective . Or compare the A-bomb with a nuclear powerplant . The efficiency of the bomb is a better one then that of the power plant .....(stupid sample !)
To the flow meter : It is not so important what the flow meter/restrictor shows as such , they can be quiet inaccurate anyhow. What counts is the actual heat in the return pipe from the corresponding zone . This would be meassured and  the restrictors adjusted to give an even temperature on all of them .The " float- in- a- window "   flow meters are more for the installer of the UFH,  for the handy man/women, to give a rough indication when installing the UFH . At the point of installing a lot of things aren't clear , for example the heating can't be tried out because the screed hasn't dried yet , the tiles (and their adhesive ) still to go on top of the screed would have different thicknesses ( U-values ) and so on. The fine tuning is done when everything is in place and the boiler is running for an hour or so. And check it again every heating season , the boiler maintenance company might be able to do that for you when servicing it. But as said: all you need is a thermometer that takes the temperature straight at the return pipes . 
The neccessary adjustment can be done at the returns or at the flows , it doesn't matter .Compare it with trains entering a tunnel : no matter from what direction they come from they always have to push the same amount of air through the tunnel . And this moved air gives  the same resistance .
So restricting the flow at the inlet or at the outlet makes no difference .


----------



## taylorcarl

*Re: >>Underfloor Heating*

Hi,

Ive just bought an old house in Spain.  An hour inland from Alicante in the mountains.

Can anyone give me information about Under Floor Heating and european suppliers/companies.

There is no mains gas available in my village so therefore we would have to run it on Electricity.  Is this expensive?   

Anyone have any experience of using solar powered energy to run UFH?

Geothermal heating system, good bad?  We live in a townhouse with little outside space apart from a couple of terraces.  So is geothermal system possible for me?

Any help/info would be greatly appreciated

Thanks


----------



## z102

*Re: >>Underfloor Heating*

It is propably difficult and expensive to bring in staff and material from abroad . So contact the locals. Spain is destinated for solar heating , the gouvernment is subsidising the installment of solar heating systems as well as photovoltaic energy production . Their photovoltaic support system is the leading one in Europe , for every kW delivered to the grid the producer gets € 0.55 cents from the electric supplier/grid company.   
Your first aim should be to save energy , by insulation for example. If your house is in the mountains then it could be a total different story compared to the coast . Again : talk to the locals .Spain has tree different climate zones as France as well .So there is no one-fits-all heating system . The first thing to find out is your heating demand , expressed in kilo Watts . Check you meter box when you arrive and again when you leave .
For a holiday home used only temporarly it might be worth it to use electricity , but for a sales point of view certainly not .Electric heating  is cheap to install , but underfloor heating running on electricity is very expensive to install and to run . Night saver might be a thing of the past , the Germans are indicating that they won't replace the old  power plants because of the CO2 emission trading . And it is the old powerplant that delivers for cheap - till it collapses . Spain is upgrading their old power production system , even the ESB is involved , incl. the IRA/ ETA to skim them off .


----------



## JPSaltee

*Re: Users of Underfloor Heating: What Settings?*

Moderators

Can this be made into a key post ? I think it will be valuable for all u/f heating users.


----------



## Sue Ellen

*Re: Users of Underfloor Heating: What Settings?*

Hi JP,


I will merge it in due course with the key post on underfloor heating.


----------



## kfpg

*Considerations to Balance Temperatures at the Manifold*

I tried to use the advide of Heinbloed in this post to balance the return temperatures of each loop on the manifold but found it was not so easy;

To measure the temperature I had a digital thermometer but it only had a sharp point (like a meat probe) so it was hard to get a good reading. I could not find in Maplins something which might clamp on.

In order to get warm water running through the loops (in order to check the return temperature) I had to put up the temperature request in each room to say 23 or 24 degrees (even though it would never each it) but now this is not like a real situation when I normally only look for 19 to 20 degrees.

In this balancing exercise it is also not like real life usage because from 9 return loops on the manifold at different time zones of the day the settings on the thermostat could request different temperatures which means some zones are open and some are closed. Furthermore even if the temperature request was the same the valve could be closed for a looop supplying a sunny room but open to heat a loop in a shaded room perhaps with a north exterior. Therefore different combinations of 9 loops could be open or closed at any one time - so what is the point of balancing 9 open loops which probably rarely ever happens?

Finally I find a contradiction in general with my underfloor heating. In theory it is more efficient to keep the floor slab warm all the time. It is also in theory better to conserve fuel by not overheating the house and setting just a 19 degree living temperature for example.

So the contradiction is in a well insulated house with also some passive solar gain the general temperature without heat could be close to 19 degrees indoor without heating at all. Or with heat for an hour or two the house can retain its pleasant temperature easily for a long time. In the time then when the heat is maintained or already 19 degrees then the stats don't call for heat and no warm water flows in the loops so the floor gets a good chance to go cold all the time !!!

In the instance where I feel cold and push the stats to 20 or maybe 21 degrees then the system is starting off from zero with an entire cold floor slab to heat up which is slow to happen and hard on fuel usage !!!! (see my other post today on costs of LPG so far included in a post about litres of oil used in 5 weeks by another poster)

Anyone else tried this 'balancing act' or have similar undefloor heating issues - I t


----------



## z102

*Re: Users of Underfloor Heating: What Settings?*

You haven't understood the idea of adjusting the loop return temperature. See also http://www.heizungsbetrieb.de/en/index.html , it's done worldwide. 
If one loop closes then the flow rate on all other open loops increases, therefore as well the return temperature at each of them. Because the hot water hasn't got that much time to reduce/give off it's energy.
But this will happen similar, at all loops at the same rate.Take the sample of a fountain in the park with four jets spraying water: If you close one of them the other three would blow the water higher, further-at a similar rate in liters per minute. Close the second jet as well and the remaining two open ones will spray even higher/further. At a similar rate. 
Provided they are adjusted.
Use an infrared thermometer, read the manual of it before adjusting the return temperature, the instrument you've described gives mostlike no compareable results.
This should be the job of the installer, but it's easily done.
The difference between floor temperature and ceiling temperature should not be higher then 2 degrees with UFH. If it is more then the floor is badly insulated. Use the thermometer.
The room temperature should hold the floor temperature at it's level, if not then the floor is not good enough insulated. Why should it be colder? The actuall room temperature is controlled by the thermostats, if it gets warm then they close off all further flow in the UFH untill they sense a room temperature drop and open the valve again. That is normal with any room/zone thermostat.
One other point: The room thermostat does NOT set the flow temperature. This would be done by the boiler.
The thermostat opens and closes the loop, not more.
One question: Do the floor buildups differ between the different zones? For example do you have timberfloor fixed on concrete screed?


----------



## kfpg

*Re: Users of Underfloor Heating: What Settings?*

I am going to look for an infrared thermometer and start again!

Yes the floor build up's do vary - it is solid timber (17mm) glued down to a concrete screed on top of insulation layer in many rooms (bedrooms & living areas) but it is tiles in other places (utility, toilets, hall, landing etc).

Downstairs insulation was Kingspan TF70 at 65mm and the same product upstairs with 25mm thick. I think this is more than minimum required but of course like all insulation it could be more, even double!

My flow temperature is set by the boiler and currently 43 degrees but perhaps in my case this is not high eneough to penetrate the timber / glue layers?


----------



## z102

*Re: Users of Underfloor Heating: What Settings?*

It looks to me that your UFH was installed in an amateur manner. Get a heating engineer in to write a report. Your UFH seems to be better insulated from above then from below. 65mm under the UFH downstairs is less then the legal min., check the SEI homepage for their min.recommendation (10cm). 25mm under the upstairs UFH is only good if you want to heat the ceiling below when turning on the heating upstairs.The tiles and their adhesive (glued to what actually?) propably have a better insulation value(U-value) then the Kingspan board below.
When having this report bring the architect/UFH installer to the courts.
If you increase the temperature too high then the tiles might come off, as well as the timber floor might get demaged.
I run my UFH at the moment/ the last few days at 32 degrees, but it was turned up to 39 degrees when it was minus 5C a few weeks ago. 
Sorry for not having better news, good luck.


----------



## 10to1

*Re: Users of Underfloor Heating: What Settings?*

My boiler output varies from min. of 60 Celsius to max. 90 Celsius. Is this ok with UFH. Just read some Lakeview's post where he mentions 45C


----------



## kfpg

*Re: Users of Underfloor Heating: What Settings?*



			
				heinbloed said:
			
		

> 65mm under the UFH downstairs is less then the legal min., check the SEI homepage for their min.recommendation (10cm). 25mm under the upstairs UFH is only good if you want to heat the ceiling below when turning on the heating upstairs.


 
Obviously I will check what you are saying (didn't find it on SEI first attempt) BUT I believe insulation requirements are not met by a function of thickness only but the thermal properties (U value) of the boards. I believe the U value of the board I used delivered at least (if not more) than the minimum requirement !!


----------



## z102

*Re: Users of underfloor heating: what settings?*

To 10to1:No, your boiler is not suitable for UFH without adjustment. This would be the job of a heating engineer, most plumbers wouldn't be able to do this.It would be more energy wise to get a new,modern modulating condensing boiler with a very low min.output. I think the lowest output is aroud 2-3kWh with some types.
And to Lakeview: The legal requirement for floor insulation is about the amount of insulation that you have in place. But the legal requirement is not good enough for UFH, this would demand an extra layer of insulation material.The "Technical Guidance Documents" of the building regulations do not take care of UFH, the U-values given there are for the standard heating i.e. radiators and the like. Check the SEI page's search box for "floor insulation" or a similar word.


----------



## FLOMAN2008

Hi, does anyone know or can recommend which is better for underfloor heating... QPL in cork or Unitherm? We are trying to make a decision on it and need a few opinions??


----------



## Decisions!

I am also interested in the answer to Floman2008's question.

And have more questions: Has anyone ever dug up existing floors to install underfloor heating?

We have bought a 10 year old house which we are extending on either end. The existing radiators are corroded and need replacing and we're considering replacing all the pipework too. It was initially suggested that we put underfloor heating in the extensions but then told that the pipework has to come through the existing part of the house to the hotpress/central control unit so we might consider doing underfloor heating in the whole house. This means digging up the floors.

I'm the kind of person that jumps from bathmat to carpet and into slippers to avoid touching cold floors. I can't imagine anything getting too hot. I'm mostly concerned about the cost of running the system after the extra cost of installing it.

Can underfloor heating be run off renewable energy (not considering geotherm, too expensive to install)?


----------



## carrotcake

*Re: Key Post: Underfloor Heating - Can I use vinyl and carpet flooring?*

Hello, may I ask advice here please? I am putting underfloor heating in house and wanted to ask if it is possible to use vinyl flooring (karndean/good quality lino) and carpets with this type of heating system as I am not keen at all on tiles (except for bathrooms). I have visited several floor shops and some of them tell me that vinyls can be used with underfloor and some say that it cannot.....who is right?? (I understand that carpet can be used with underfloor heating). Has anyone out there used vinyls (i.e. lino/amtico/karndean etc.) or carpet with their underfloor and if so, has it worked out fine for them?  There is a wonderful array/choice of vinyls/lino's out there now. Thanks very much.


----------



## guernseyguy

I am trying to follow Heinbloed's guidance above 





> Zones pipes have different sizes . Some are fully 150 meters long , some are just 30 meters long .
> So sending IN the same temperature would result in different temperatures coming OUT . This shouldn't happen .
> To adjust this dilemma the " standard " for adjusting is the largest i.e. the longest pipe . This is not necessary the one from the biggest zone , it could also be an average sized zone but in a far away place in the house . The lenght of the pipe decides .
> When you have found this pipe you turn the reducer fully open by turning its base , not the looking glass itself . To make as much warm water passing through the zone as possible .The little float in the reducer shows how many liters are flowing through the pipe . Read always at the lowest point of the little floating ball .
> Then you go to next longest pipe . Measure the temperature at the return as described above . If it shows a larger temperature as the first one then you close the return valve ( the thing with l/min. on it with the float in it ) by turning it's base until the temperature is equal to the one you have done first .
> Then you go to the third longest pipe . Again the same story . Reduce the liters per minute that pass trough the zone untill the return temperature at this zone is similar to the two return temperatures you have meassured before .
> And so on untill you have reached the return of the smallest zone/shortest pipe.
> All return temperatures should be the same .


. My question is: Should all the reducers be fully open when starting off this process, or should I open the reducer for the longest loop first with the other loops closed and opening them one by one?


----------

