Key Post: Underfloor Heating

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.

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.

heating

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

Re: Underfloor Heating

Thanks MOB.

Anyone got comments on products & installers?

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.

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?

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.

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.

cost

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

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 ?

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]

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 .

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 .

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.

"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?

Underfloor Heating

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

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.

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.

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 !!!!!

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.