# Underfloor heating running costs - help



## corkcuu

Have done searches but not finding answers in relation to this.
We moved in to our new house in june - had to refill the oil tank 2 weeks ago and we checked it at the weekend and its half gone already - it has used 450litres in 2 weeks!!

We have underfloor heating down stairs & rads upstairs. As we were off work over the hols the UFH was switched on from 9am - 11pm. Upstairs rads were only on for approx 2 hours a day. 
PLEASE PLEASE PLEASE tell me this is not the norm for UFH. To me it means there must be a problem??? Any help or advise would be greatly appreciated on this.


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## JoeHooker

Oh theres a problem and suddenly the UFH is to blame, it all depends on the size of your house really and if theres any drafts. Maybe theres a leak in the pipe, UFH is designed to run at 20 - 22 degrees, I think there are major problems when you mix UFH and normal rads. In my opinion its a very bad idea.


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## corkcuu

I am not blaming the UFH but my problem is that spending €400 on oil in 2 weeks must signify a problem somewhere.

Our house is 2800sq foot. No drafts. The rads are running at 20, however the UFH is only running at 18 downstairs. 
How can we check for a leak?


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## manaboutdog

Is the tank easily accessible? There have been cases in my locality of certain nefarious individuals siphoning heating oil from homes into concealed tanks in the back of vans etc.

Just a thought.


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## galwaytt

remember you're looking at a money amount, not an oil qty. Oil has gone through the roof, so you're getting less and less oil for the same amount of money..........the heating system, whatever way it's set up, is probably more or less constant.....

But it's still worth getting your system checked out. 

Personally, it sounds like your heat is on too long, per day.  My ufh, which I'm still fiddling with, is on 06:30-07:00, 12:00-12:30 and 16:30-21:30. 

I'm with Joe Hooker - rads + ufh are a nightmare.  The boiler needs 60 deg water for rads and dhw, and only 30-40 for the floor.  Very hard to get the thing sync'd correctly.


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## ted

Hi Corkcuu

Running your system from 9am to 11 pm will def cost you more. Besides the obvious i.e. house size, desired temp, insulation, glazing etc. etc. that influence the heating costs, the amount of time you run the system will have a significant impact on costs.

For example in my home I have 160m downstairs on UFH and 90m upstairs also UFH.

I turn on my boiler for 3 hours for downstairs and 1 hour upstairs at this time of year. As the return water never gets to 60 C (my lowest setting on my Firebird 120) the boiler remains on continously. 

Costs

4 hours @ 3.1 litres/hour (the oil flow rate for the boiler) = 12.4 litres per day

On this basis I will get 80 days from a 1000 litre tank of oil for €690.

Some days the heat requirement is higher and other days lower. It depends on the outside temp and sunlight.


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## laragh

Hi corkcuu,

There may very well be a problem with your system so it might be well worth your while getting your installer to come back and check it out.  Have a good record of how much oil was used- when you bought it, how many litres, when you refilled again. It's better to have hard facts rather than saying 'That bloody UFC is drinking oil...!'

But just to give you a glimmer of hope....
I'm in my second winter in my own house. We moved in around August 2006 and for that first winter I was watching the oil usage like a hawk- and I nearly had heart failure!!!! From June 2006 to June 2007 around 3000 litres of oil was used! Everyone I asked about this said it was normal as the house was still drying out which will mean a higher than normal heating requirement and so more oil is burned.
This winter the usage is way less- I put 1000 litres in the tank in October and there is still 1/3 of it left. And the house has been toasty the whole time. So it seems as though the system has settled down.

Best of luck in your new home!


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## corkcuu

Thanks guys, starting to breathe a bit easier now. Going to get it checked out alright still cos even though we had it on a lot I feel it is using more then it should. 
about the timing we were told by plumber & electrician we should leave it on 24hrs as once the temp sensor reaches the temp it automatically does not look for anymore heat but from reading the replies that doesnt seem to be the case. So should we use it same as radiator heating - on for just a few hours every day?


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## ted

To maintain a constant temp it's better to leave the system on all the time and let the stats call for heat as required but this is a much more expensive way of heating imho. A few hours everyday would be my preferred option. Unless it's below below zero all day outside my indoor temp drop from a 3 hour heating is about 20c to 17 c over 21 hours. Heat on from 5 am to 8 am - house warm getting up in morning - throughout day and into night and drops down while sleeping.


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## corkcuu

Thanks for that Ted. Going to try doing it that way and hopefully will see an improvement. 
Also your costs calculation above is a huge help.


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## seanmc1

i know this is a different thread but i recentley got ufh in when i bought my new house. The floor in our kitchen/dinning area is tiled but there's seems to be no heat at all.. I have the heat on at constant and the temp is at 22c. I thought the tiles are meant to have a gentle heat to them but they are freezing. Any idea's or does anyone know what am doing wrong?


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## wigster

I have UFH and Rads upstairs. Used 1200 litres of oil in my first fill in 6 weeks. (on 13/14 hours a day) This is my second winter and the oil usage has dropped to 1200 litres/16 weeks. The UFH is now only on at 2 stages per day in total about 5 hours. The Rads are probable on for 3 hours. I may experiment with running on the stats but I still do not have curtains and have a very open plan living area.


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## bobby04

My plumber recommended that we keep our UFH on 24hours. Another customer of his took this advice. Similar house to ours ~3000sqft, similar insulation levels. The other customer uses 3+ tanks (1100L) of oil per year. We used 2 tanks last year, and since last fill September 07 we still have 1/3 a tank left. So looking like ~1.5 tanks for us this year. The difference? Well, our heat is on for 45mins downstairs only in the morning (06:15-07:00) and for under 3 hours in the evening (15:45-18:30) both downstairs and upstairs. I have to say I do not subscribe to this theory that if it's on 24hrs it will only call on the boiler when room temperature drops. Sounds so logical in theory. But with 13 stats able to call on the boiler in our house, it's as if there is almost always at least one calling on the boiler at any one time. Plus, you're potentially wasting energy keeping, for example, a sitting room warm from midnight until the following evening even though it's not used. Crazy. And in case someone suggests it, our house is occupied all day with little nippers, so has to be warm all day, and it is with this schedule of heating.


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## corkcuu

we are going to try running it for 3 hours a day and hopefully that will see a big improvment. Thanks for all the advice, really helpful


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## BarneyMc

bobby04 said:


> My plumber recommended that we keep our UFH on 24hours. ....... I have to say I do not subscribe to this theory that if it's on 24hrs it will only call on the boiler when room temperature drops. Sounds so logical in theory. But with 13 stats able to call on the boiler in our house, it's as if there is almost always at least one calling on the boiler at any one time. Plus, you're potentially wasting energy keeping, for example, a sitting room warm from midnight until the following evening even though it's not used. Crazy. And in case someone suggests it, our house is occupied all day with little nippers, so has to be warm all day, and it is with this schedule of heating.


 
Bobby, just as a general question, would you recommend UFH for all new builds or is it only of benefit for those (like yourself) who have family in the house during the day?


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## rahman

corkcuu said:


> Have done searches but not finding answers in relation to this.
> We moved in to our new house in june - had to refill the oil tank 2 weeks ago and we checked it at the weekend and its half gone already - it has used 450litres in 2 weeks!!
> 
> We have underfloor heating down stairs & rads upstairs. As we were off work over the hols the UFH was switched on from 9am - 11pm. Upstairs rads were only on for approx 2 hours a day.
> PLEASE PLEASE PLEASE tell me this is not the norm for UFH. To me it means there must be a problem??? Any help or advise would be greatly appreciated on this.


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## bobby04

Regardless of whether or not the house is occupied during the day, I would definitely recommend UFH. If ours was not occupied during the day, we'd simply eliminate the morning phase of heating. What I really like about UFH is the fact that the whole floor is heated up, and so after the "oil burning phase" is over, the entire floor acts like a big, slow release, storage heater. So compared to experience of houses with radiators (and well insulated ones at that) the heat lasts longer, especially for example in the bedrooms which maintain a comfortable heat all night. In any radiator heated house we had, we always had the upstairs heat coming on before we got up. In our current house, it's just downstairs that gets a small boost in the morning. Hope this helps.


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## rahman

I've been looking at all these posts in relation to the efficiency of UFH and I believe a lot of these systems are designed incorrectly. Most UFH heating is run directly off the oil boiler via a manifold. therefore when any circuit calls for heat the boiler has to come on. this results in the boiler continually cycling on and off in order to maintain the temp within each circuit which is very inefficient.
In order to run a UFH system correctly you need to run directly off a buffer tank. As UFH typically runs at 24C and the boiler output is typically 60C there will always be a mismatch. By running the UFH circuits directly off the buffer tank which has a large amount of water at approx 38C the boiler will only turn on when the stat on buffer tank drops below 38C which if you have a good insulated tank should not happen too often. 
i will installing a buffer tank 500L in my own house later on this year. the buffer tank will be connected to a solar panel and also to the boiler so by combing the boiler and the solar panel my oil bill should be low. I will also have a step back function set on the room stats so that rooms such as the sitting room will only come on when needed in the evening time and other romms such as kitchen and living room will be on the whole time.


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## BarneyMc

bobby04 said:


> ..... compared to experience of houses with radiators (and well insulated ones at that) the heat lasts longer, especially for example in the bedrooms which maintain a comfortable heat all night. In any radiator heated house we had, we always had the upstairs heat coming on before we got up. In our current house, it's just downstairs that gets a small boost in the morning. Hope this helps.


 
Yes the heat I'm sure would last longer... whether it's needed or not :-( Personally I don't like any heat in a bedroom at night. The radiator method provides heat when required and is off when not required which in it's own way is efficient also. I realise radiators mean the water must be heated to a higher temp and this is where it looses efficiency.

Anyway I still haven't made my mind up regarding UFH so thanks for your views on it... really helpful.


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## ennisjim

Hi Rahman,
Agree with you re. buffer tank. I have 500litre tank heated from oil and solid fuel. I have solar too but it heats the separate 300litre DHW cylinder since I'm not expected much solar heating of hot water in winter. Haven't moved in yet so can't talk about efficiency at this stage.
I was wondering how you chose the setting of 38C for your buffer tank by the way ?


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## TomC

Re Rahman and Ennisjim.
I am looking at the same type of system and was considering boosting the oil with solid fuel via a stove or back burner.Ennisjim you mentioned solid fuel any information you can give me on the dual design and how it works would be appreciated. Thanks and good luck in the new house.


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## ennisjim

Hi TomC,

500litre buffer tank is heated directly from oil boiler (Grant 15-26kW condensing indoor). Charnwood SLX45 multifuel stove drives a coil in buffer tank. Buffer tank output goes to circulation pump which feeds (i) UFH manifold (210 sq.m bungalow), (ii) 'attic' rad zone (insulating large attic and preventing from getting too cold - has a simple stat), (iii) 300litre DHW cylinder upper coil. All are on separate timers. Lower coil of DHW cylinder is heated from solar. Motorised valves on each 'circuit' allow individual control from timer controller. UFH stats/controllers are Heatmiser.

Haven't moved in yet so don't know how good this design is.

Hope this helps


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## TomC

Ennisjim,

Thanks for the information and specifications, it is very beneficial. Two last questions, how far is the stove from the 500L tank and what kind of spec is the tank, thanks a million.

Tom


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## extopia

you should use fan coil rads upstairs rather than conventional rads with an underfloor system downstairs.


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## Donnachain

did you hear about thieves stealing oil from the tanks it was in the galway paper the morning. unbelievable.  so be on the look out.


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## wigster

Is the buffer tank a thermal store type that you have used?

Check out this website and About Solar Linked to Heating 

[broken link removed]


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## ennisjim

Hi TomC

I got tank from http://www.solaris-energy.com/. It is a PSA 500 dual-coil buffer tank.

Buffer tank is about 10m from stove.


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## extopia

Also, there's really no point in discussing heating costs without talking about your insulation. What kind of construction (concrete, timber frame etc) is your house, what kind of insulation, what kind of windows etc etc.


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## theplumber

In my opinion under-floor heating is not suitable for a working couple who only occupy a house for a few hours of the day
 Especially so if they are also away at weekends.  I do get requests from such people to have under-floor heating replaced by radiators.
 A conventional heating system with low water content radiators and proper controls can be far more responsive to the unpredictable Irish climate, solar gain and the lifestyle of a buildings occupants.
Renovating older property? A properly insulated solid concrete / floor slab will hold heat and be considerably warmer to the touch than the older type un-insulated solid floor.
When renovating. You do not have to install under-floor-heating to have a warmer floor.
Just ensure that the floor is insulated below the slab or timber as per recent building standards.
It is preferable to install a domestic heating system that you can afford to run.


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## BarneyMc

theplumber said:


> In my opinion under-floor heating is not suitable for a working couple who only occupy a house for a few hours of the day
> Especially so if they are also away at weekends.
> I do get requests from such people to have under-floor heating replaced by radiators.
> A conventional heating system with low water content radiators and proper controls can be far more responsive to the unpredictable Irish climate, solar gain and the lifestyle of a buildings occupants.
> .....


 
Hi Plumber, You seem to be in the minority with this opinion. I've asked this question a few times and all responses seem to think underfloor (especially with new build) is the only way to go. I believe underfloor is a good method if the house is going to be occupied every day in really long cold winters but, like yourself believe it's not suited to Irish weather that changes so much.

Can you specify why exactly some people are unhappy with their UFH systems and replaceing it with radiators... UFH not working properly, too expensive to run, too slow response time, difficult to manage for different parts of the house, hard to predict when the house will be occupied, etc.?


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## sydthebeat

BarneyMc said:


> Hi Plumber, You seem to be in the minority with this opinion. I've asked this question a few times and all responses seem to think underfloor (especially with new build) is the only way to go. I believe underfloor is a good method if the house is going to be occupied every day in really long cold winters but, like yourself believe it's not suited to Irish weather that changes so much.
> 
> * Can you specify why exactly some people are unhappy with their UFH systems and replaceing it with radiators... UFH not working properly, too expensive to run, too slow response time, difficult to manage for different parts of the house, hard to predict when the house will be occupied, *etc.?



Its funny that you didnt include in that list the possibly most significant reason for the switch from UFH.... the unsuitability of the dwelling construction..... 
people are quick to blame the UFH for the slow responsiveness, but in reality the generated heat is pising out of their houses through bad construction detailing or bad fixtures in opes etc. 
UFH works perfectly in well built, airtight dwellings with Heat recovery Systems.
I have often stated that i wouldnt dream about incorporating UFH into a conventionally built 310 cavity wall house with passive ventilation. There are way too many chances of having bad construction detailing to risk it.


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## BarneyMc

Yes Syd, I suppose there are a lot of variables. However let's assume the house is well constructed, airtight, etc. For a couple who don't be in the house during the day, then is UFH still a good option or just use radiators when required?

It seems to me there is a certain inefficiency with UFH when you consider the house may be unoccupied during the day and/or weekends, nights out, spring and autumn days when the heating simply isn't required but you don't know beforehand etc?

Take a couple who decide to head off for a weekend. The UFH must be left on over the weekend (at a low rate but it's still on). Also in autumn and spring the system must be kept ticking over for the odd cold day.

Anyway good to hear different ideas on this as I may yet go for UFH!! - playing devils advocate!!


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## sydthebeat

UFH only has slow responsiveness if the standard of construction determines it.
If there is high thermal mass to be heated before the ambient air, ie a thick concrete slab and plastered 100 dense concrete block inner leafs, then the responsiveness is going to be slow. However if there is only say 65mm or less (easi-screed etc) screed and the inner walls are SIP panels or ICF panels, then the heat is reflected immediately back into the ambient air. 

Personally i believe only internal walls should be designed as the thermal mass 'emitters'.... they should gain passive solar heat in winter, and be protected from gaining solar heat in summer.... and because they are located within the insulation envelope they shouldnt loose heat at the same rate as your external walls.


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## kildarebuild

27th November - put in 1000 litres of oil into our tank. Empty on the 8th of january. So it was all used up in 6 weeks...

Underfloor heating on both floors (precast floor), buffer tank, oil condenser, plenty of drafts (have to seal a few more up at the wkd.) But i think i will be switching to the timer now. It was on 24/7 as recommended by the plumber

Size of house is a 3000sq ft dormer. 40mm insulation with plasterboard on the inside of all external walls. 100 xatherm in the pitch between rafters. 300mm fibreglass top of the attic.


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## wigster

I would go with UFH again as I think its is a very comfortable heat. However I would put in insulated slabs as I believe that heating block walls is a waste. 

If I turn on my Rad in the upstairs it becomes nice and warm but the minute I switch off the rads the room loses 2/3 degrees within a 1/2 hour. I put in Kingspan insulation and sealed around all windows.


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## mikeor

Currently have underfloor installed in a 2000sq ft house on ground level.  Have rads installed on the second floor which was converted.
New build and moved in almost a year ago.
Block build, 4 inches of hytherm in floor, 65 mm hytherm in walls, 8 inches of rockwool in 9 inch joices and 145mm of hytherm in rafters.
When I started underfloor I used up 1/2 tanks of oil very quickly as zones were on 24/7.
got 1000 litres of oil last april and it lasted until end of december when i was running heating on a timer.
timer heats water from 5-6, then underfloor is on from 6-7.  Comes on again from 1-3.  Then from 5-7. Finally from 7.30-9.
After 7.30 boiler is usually never on as rooms have required heat so stats have turned off the boiler.
i built my house on a height so can be cold but have to say underfloor works great.


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## theplumber

Plumber here again I´m sorry but but no  matter what way you dress it up radiators is the most efficient way to to maintain a minimum air temperature in defined space. (given Identical build)

What certainly tips the balance in favour of radiators is responsivnes esspecially to solar gain and nights out.

UFH users are wasting energy everytime they pop down to the pub for a couple of hours. I didn´t think of that.


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## BarneyMc

theplumber said:


> Plumber here again I´m sorry but but no matter what way you dress it up radiators is the most efficient way to to maintain a minimum air temperature in defined space. (given Identical build)
> 
> What certainly tips the balance in favour of radiators is responsivnes esspecially to solar gain and nights out.
> 
> UFH users are wasting energy everytime they pop down to the pub for a couple of hours. I didn´t think of that.


 
Anyone think UFH is more efficient?


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## bobby04

The plumber makes a very valid point about wasting heat while down the pub for example. But I still think the comfort of the ufh far outweights this relatively minor draw back (especially when you don't get to the pub much!! ) Plus solar gain will serve to reduce the amount of time the room stat is calling for water for the ufh, so sorry if I'm missing something there, but don't see how radiators are better in that sense. 
For a house that is empty alot of the time, then yes radiators would probably be cheaper for heating the house for short periods.
If the house is occupied most of the time, I'd say ufh is cheaper.


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## BarneyMc

bobby04 said:


> The plumber makes a very valid point about wasting heat while down the pub for example.


 
Is ther not a lot of heat also wasted in the spring and autumn months when some days require heat and some don't? Doesn't the concrete slab have to be kept heated (at a low temp) even during the days when the heat is not required?

Surely UFH is for winter months only and another heat source such as a stove should also be used for spring/autumn days?


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## sydthebeat

BarneyMc said:


> Is ther not a lot of heat also wasted in the spring and autumn months when some days require heat and some don't? Doesn't the concrete slab have to be kept heated (at a low temp) even during the days when the heat is not required?
> 
> Surely UFH is for winter months only and another heat source such as a stove should also be used for spring/autumn days?



The concrete 'slab' should be kept as minimal as possible..... at most a 75mm screed should be used, and if possible an 'easy screed' type should be used.

The external walls should be made of a material that will instantly redirect the heat back into the rooms, ie SIP panels or ICF walls.... even insulation backed plasterboard.

Its all about improving the responsiveness of the heating system.
And dont install UFH is you have passive ventilation.


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## ennisjim

Hi sydthebeat,

What's the problem with passive ventilation and UFH ?


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## angela59

Hi,

Question for sydthebeat.  OP excuse me for jumping to a different question.  Sydthebeat - if you were building a house yourself, highly insulated and highspec windows and for ventilation HRV - would you install geothermal heat source or would you go for good condensing oil burner?  Would apprciate your expert opinion.  The building material aim to use is poroton block and clad in natural stone.

Many thanks angela59


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## sydthebeat

anglea, if you can get your house to as close to passive standards as possible then it really doesnt matter how you heat it. Thats no a flippant answer.. ill clear it up a bit.
We all know the pros and cons of oil vrs geothermal vrs wood pellet etc.

If you have an extremely well built, high spec, even passive house then it will require a minimum of heating...... geothermal may actually work out to be uneconomical (initial installation cost wise) when compare to the output required. Oil will always increase in price and whilst cheap to incorporate initially, there are better options.

If you have a 'close to' passive house i would try as best i can to design a solar collector based heating system, with a wood pellet boiler, as back up only, and perhaps a wood burning stove with back boiler, serviced by a double skinned flue. People do not appreciate the actual gains from passive solar design... a dwelling well designed with these principles, and well constructed, can be heated for 7-8 months a year free... thats not an exaggeration.

ennisjim.... passive vents allow fresh air in at 'outside' temperatures... for example last week probably 1-3 deg c... this needs to be heated up to 21-22 deg constantly.... 
depending on external wind conditions a passive vent may change the air in a room completely in possible 1 1/2 hours... therefore, on a cold windy day, you need to heat the room completely from 2 - 22 deg c every 1 1/2 hrs... and this assumes no other exhaustion of air through the building envelope... which of course will exist anyway.
HRV systems will heat the incoming air to approx 14-16 deg when exhausting 22 deg stale air.... this makes a huge difference to heating costs.
UFH works on a lower temperature than rads, so if it is made to work harder to heat cold incoming air it becomes less efficient, and therefore i dont recommend UFH with passive vents.


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## angela59

Hi Sydthebeat,

Thanks for reply and value all the information you supplied.

Angela59


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## ennisjim

Thanks for clarification sydthebeat. It would be nice to install HRV but quotes for approx €7000 decided that for me. Hopefully it will get cheaper.

At the same time, I know several people with UFH and none have HRV and they are happy with UFH - though maybe they've just blocked the ventilation holes in their walls !


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## sse

We have HRV and UFH downstairs - there is a dedicated (gas) condensing boiler running this. We've had the heating on 24x7 at the lowest setting on the 'stat for each zone since we moved in - the boiler seems actually to be on about 20% of the time. We have insulated boards on the external walls, lower u-value glass, extensive S and W glazing and 100mm TF insulation under the screed.

I'll post the running costs when we get the bill!

SSE


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## angela59

Hi,

Could anyone recommend a good wood pellet boiler to run ufh and also if anyone has good experience of HRV unit.  

Thanks in advance, angela59


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## Optimistic

whatever wood pellet boiler you get, be sure that it is modulating, ie give the amount of heat you require at a given time. We have a Windhager and are delighted with it.  All the best whatever you decide.Optimstic


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## angela59

Hi Optimistic,

Funny just reading through your previous posts just a minute ago, we're gearing towards wpb having previously geared towards geothermal - the initial outlay on geo is very expensive and when you are trying to build a house to a high spec something has to give along the way so I'm glad of all the advice.  thanks optimistic


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## sas

angela59 said:


> Hi Optimistic,
> 
> Funny just reading through your previous posts just a minute ago, we're gearing towards wpb having previously geared towards geothermal - the initial outlay on geo is very expensive and when you are trying to build a house to a high spec something has to give along the way so I'm glad of all the advice. thanks optimistic


 
If you thought Geo is expensive wait until you get a price for the windhager. They wanted the bones of 20K from me and this didn't include the plumbing!

On HRV you could talk to www.atc.ie. They sell a vortice model which apparently scores the highest efficiency rating on the british SAP system. They also sell the ducting system which was also tested. Its quite inexpensive but is a self install which might be off putting. Usual disclaimer, no connection with ATC.

Incidently, I'm told that virtually none of the HRV systems available at the moment in Ireland have an efficiency rating that can be used in the DEAP software for you BER certificate i.e. they are not tested by an independent body as yet. You will be stuck with the default efficiency. This may not matter to you of course. The SAP ratings can be used however. Sydthebeat can confirm this of course but this is what I was told by a BER accessor.


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## angela59

Hi sas,

good to hear from you again. The windhager certainly sounds expensive 20k is a lot - optimistic quoted 11k though he knew the guy - this figure may not include installation. Will have to research a bit more to see if there is anything as good as windhager but not as expensive. thanks for advice SAS. By the way SAS did you get any further quotes for windows or at leas any better than the E46,000 or thereabouts that you were last quoted.  Would love to know.

many thanks angela59


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## sas

angela59 said:


> Hi sas,
> 
> good to hear from you again. The windhager certainly sounds expensive 20k is a lot - optimistic quoted 11k though he knew the guy - this figure may not include installation. Will have to research a bit more to see if there is anything as good as windhager but not as expensive. thanks for advice SAS. By the way SAS did you get any further quotes for windows or at leas any better than the E46,000 or thereabouts that you were last quoted. Would love to know.
> 
> many thanks angela59


 
I spoke to the same guy optimistic dealt with. Optimistic got his a while back and plus you should keep in mind that the greener homes scheme is very likely to disappear underneath us any time now so unless you have grant approval, don't include that in the costing either. There were other little nuggets too like you had to be willing to commit to a €150 per year servicing contract for 5 years or it affected the guarantee!

Seeing as we've hijacked this thread I'll take the rest off line with you.


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## sydthebeat

sas said:


> Incidently, I'm told that virtually none of the HRV systems available at the moment in Ireland have an efficiency rating that can be used in the DEAP software for you BER certificate i.e. they are not tested by an independent body as yet. You will be stuck with the default efficiency. This may not matter to you of course. The SAP ratings can be used however. Sydthebeat can confirm this of course but this is what I was told by a BER accessor.



There is a facility to input the manufacturers declared efficiency.
The default is 66% with a power requirement of 2 W/l/s.....
Once the 'declared' values are in accordance with an approved calculation method then there is no problem using them.

It is worth noting that using a HRV reduces the effective air change rate from 0.5 ac/h to 0.17 ac/h... which is quite significant on a high spec low energy dwelling.


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## sydthebeat

PAYEPLEB, love the name by the way....

You have done the most important thing right already..... the HRV systems is a must... the insulated slabs on the inner leaf is also a good idea once they are installed correctly. If they are just spot daubed then there may be 'thermal looping' problems as an open cavity is formed behind the slabs. If they are continuously 'ring' sealed then they will be fine. If they are daubed then i would consider taping up all joints, giving particular energy to taping up ceiling / wall and floor / wall junctions. A skim finish over this should create a fairly air tight construction.

Once your construction is airtight and well insulated, then whatever heating system you use will not be running inefficiently. The 'greener' client would install a wood pellet burner now, by these technologies may not be perfected yet. The solid fuel stove is a good idea, but one thing that is certain is that solid fuel and oil will rise in price..... at least you have the option of converting in the future.

UFH heating works best with either geothermal or solar collectors. UFH and oil is not an efficient system.


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## sydthebeat

yes is the answer to your question....
Thats the very system my parents have... solid fuel stove in kitchen heating centrally, with oil back up...

They hardly ever have to turn the oil on, but its designed so that if the oil and stove were lit at the same time, the oil would heat the system until the stove was heating to a certain level, then the oil would click off and the stove would be the main heating system. So both systems could actually be 'on' together but both would not heat at the same time.

How is your insulated plasterboard fixed to the walls???


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## sydthebeat

PAYEPLEB said:


> Haven't started yet as house isn't covered and no windows in. I'd say i'll be fixing it directly onto the wall and taping any little crack or opening I can see



Just remember to create a continuous bond at all junctions, especially floor and ceiling, leave no gaps. If you do this you can actually trap air which will act as an extra insulator as well.


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## galwaytt

theplumber said:


> Plumber here again I´m sorry but but no matter what way you dress it up radiators is the most efficient way to to maintain a minimum air temperature in defined space. (given Identical build)
> 
> What certainly tips the balance in favour of radiators is responsivnes esspecially to solar gain and nights out.
> 
> UFH users are wasting energy everytime they pop down to the pub for a couple of hours. I didn´t think of that.


 
given that we don't float in mid air, and walk on the ground, that's a bit moot....

I couldn't disagree more about rads. They are fundamentally flawed, promoting convection (.i.e 'draughts') by dint of phyics - heat rising, and all that. 

So, from the rad, air has to rise (along wall/window  ), across ceiling, and down the other side of the room. Essentially, it is heating the space from the ceiling down. Again, with me being only 1.7m high, that's no good to me.....

UFH on the other hand, heats from 'ground zero'. From the minute it radiates heat, it heats the person (by conduction, through contact), and heats the air from the floor up - iow, where you're more likely to find people/cats/dogs/life..........

And you're forgetting that other benefit: you are not confined to placing the couch/dresser etc,as all walls are 'free'. Walls with rads, on the contrary, are limiting in terms of furniture placement, but even more importantly, are limiting by dint of having the convection current of air interfered with by furniture position - so, you can't put the couch in front of the rad etc etc. without interfering with the heat quality in the room.

I mean, how many of us have seen people sitting/hogging the rads? Exactly, it's because the heat is all in the wrong place.

And then there's thermostats:  'stats on the wall for rads can be hopelessly useless, being affected by poor placement and giving inaccurate results.  In a house with HRV, it's even worse - I've seen one located near the air input, so it was being 'chilled' by incoming air, so room was constantly too cold.   TRV's, although better than nothing, also suffer from being below the heat source.  The whole room has to heat up first, from ceiling down, before they are effective - by which time, it's too late.


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## sse

PAYEPLEB - one thing you might want to do is add in a couple of extra pipes to the loft area and get a tank with an extra coil - just in case you want to get solar at some point in the future. It'll likely be easier to do this during the build.

SSE


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## theplumber

When discussing the merrits of different types of heating systems one should always compare them on the basis that they are correctly installed.


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## extopia

theplumber said:


> When discussing the merrits of different types of heating systems one should always compare them on the basis that they are correctly installed.



Well of course.

There is no evidence to suggest that a properly installed radiator system is better than a properly installed UFH system.


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## BarneyMc

I've seen it commented here so often that an air tight house is essential for UFH. Of all the houses with UFH how many could be considered air tight (or how many have had their house measured for air tightness and passed)? Perhaps 5% be an accurate figure?

If building a cavity wall house for example would it not be pointless using UFH as so many commentators on this site have said it is almost impossible to build an air tight cavity wall house? Just interested.


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## sydthebeat

Just a matter of note....
thenew revised Part L regs coming in in july require any floor with UFH to have a uvalue of 0.15....!!!!!!

basically that means that if you have any kind of a dwelling thats not a shoebox you will need at least 125mm of PU (kingspan / xtratherm)......... compare that to what people are currently installing....

and barney... you are completely correct with your last statement.....

and this causes problems like people stating that UFH is crap etc when they dont realise they are living in a sieve....


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## extopia

Bear in mind of course that radiators are also not very well suited to heating drafty houses.


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## BarneyMc

extopia said:


> Bear in mind of course that radiators are also not very well suited to heating drafty houses.


 
Here's my reading on this....

Yes obviously a draughty house is not desirable for anyone but it just seems that since UFH uses a low heat (an this is where it is economical) it is greatly dependant on air tightness. With this combination (low heat and air tightness) it's very economical.

In non-airtight situations (vast majority of houses) most people turn the heat up to try and compensate for leaking air... low heat scenario is changed to higher heat scenario and becomes more uneconomical.

Perhaps it's better to sum up as UFH really needs air tightness as it's a low heat system and can only work as a low heat system if there is good air tightness. Radiators provide a blast heat so better able to get the room to desired temp even if not air tight. Which one is more economical is the big question. And bigger question for all is perhaps how to acquire air tightness!!


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## johnnyg

if you have UFH, the heat is radiating from the floor up across the floor, so if you do have draughts is this not a better system to have, the only i place i can see air entry into a house is in the wall vents or trickle vents on the windows, which can be controlled aswell..or maybe i haven't seen very draughty houses. I was told that you cam buy wall vents that actually open and close depending on the weather ie winds outside, has anyone come across these?


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## BarneyMc

johnnyg said:


> the only i place i can see air entry into a house is in the wall vents or trickle vents on the windows, .....


 
windows is another obvious place if not properly fitted.

For cavity wall house where else is a source of air leakage? Electrical sockets, cracks in wall, joining walls, walls and floor joins?

Can some sort of "membrane" be used to seal a cavity wall house?


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## rahman

BarneyMc
you can use a vapour check as air control barrier. Products such as Tyvek SD2 or Intello can be used to seal inner leaf and prevent air leakage through block wall. these products can be sealed to the ceiling and floor and then taped to ensure air tightness. I am in the process of a self build and I am still investigating the best method to adopt.
However if you employ this method you must remove moisture from the internal air. the only way to achieve this is to use a HRV system whereby all warm moist air is removed from the house. 

I do believe that making a house airtight is extremely difficult with tradional cavity block construction. Passive houses are the future and the use of breathable materials such as wood fibre softboards is the way to go. Alas builders in this country are totally ignorant to idea of air tightness in a house


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## johnnyg

but if these are insulated properly, this will eliminate these eaks, i think when you are building a once off you have more control of what is going on and you can take steps to correct it when it appears, my plan is a cavity block built with concrete floors and pumped insulation which should seal up the cavity and eliminated these draughts..


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## extopia

johnnyg said:


> but if these are insulated properly, this will eliminate these eaks, i think when you are building a once off you have more control of what is going on and you can take steps to correct it when it appears, my plan is a cavity block built with concrete floors and pumped insulation which should seal up the cavity and eliminated these draughts..



Why bother with a cavity at all if you're going to just fill it up with insulation? Why not consider a solid method, such as Poroton - much simpler.


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## johnnyg

extopia said:


> Why bother with a cavity at all if you're going to just fill it up with insulation? Why not consider a solid method, such as Poroton - much simpler.


...cost, Poroton is way too expensive and trying to get some one to use this new method is quite hard !!!!


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## extopia

Perhaps you're right about it hard to get a blocklayer to use Poroton. I was faced with this problem a few years ago and in my frustration decided to lay the blocks myself

Now I'd never laid a block in my life before, yet I completed two 2-storey Poroton-built extensions by myself in 15 working days. Yes, the blocks were expensive (about €40 per sq metre) at the time, but I saved a lot of money not having to pay a blocklaying crew.

The results were very pleasing, and the house feels very snug. The Poroton people at FBT in Enniscorthy will give you all the assistance you need. (I have no affiliation.)


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## Denden

Does the boiler need to run 24/7 for max efficient underfloor heating. Are there any figures running times.


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## extopia

Denden said:


> Does the boiler need to run 24/7 for max efficient underfloor heating. Are there any figures running times.


 
I'd say this is no different for UFH than any heating system. If your house is well insulated and there is minimum heat loss, then why not run the boiler 24/7 at a comfortable room temperature. If your house does not retain heat, it makes no sense to waste heat when you're not there, or you're asleep, no matter which system you use.


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## sman

After going round in cirlces on Wood pellet vs oil and whether to use UFH or rads in my bungalow (approx 2750) . i am considering going for oil condenser with a solid or pellet stove linked to the boiler. I am thinkin of putting UFH in the living areas and then just usings rads in the bedrooms. We would like UFH in the living areas as we have young kids and would like the comfort. I was considering wood pellet but was told that i would be looking at about 20k as opposed to 5k for oil. I will hopefully switch in future when it becomes less costly. I have read that mixing UFH and rads is inefficient but my architect recommended a mixing system which overcomes this. Has anyone any experience of this? or am i going for a bad system? If i am going for this should i also install a buffer tank? Can someone give me a spec for what i should go with? I am putting in extra insulation and a heat recovery system. Thanks


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## Robocop

Corkcuu,
     somebody is obviously, siphoning your tank of oil. This has become a more common crime since the price of oil has been rising so much. Put a lock on your oil tank.


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## Neadyk

Can anybody give me an idea of installation costs for both rads and UFH as opposed to running costs.  It is for a house of approximately 200sq meters.  I presume rads are somewhat cheaper to install than UFH.  I think we are going for an oil condenser as well as solar panels although this will only heat water.  Advice appreciated.


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## Leo

Neadyk said:


> Can anybody give me an idea of installation costs for both rads and UFH as opposed to running costs.



Post this in a separate thread, this one is on running costs!
Leo


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