Underfloor Heating

bdoo · 14-07-2009 9:43pm #1

Hi,

Planning is gone in and we're trying to make a good few decisions now before things really get going. One of the things we really can't decide on is underfloor or radiators for heating.

can anyone advise? House is about 280m2 i.5 storey.

JuniorB · 14-07-2009 9:58pm

Best of luck Bdoo .. not too far ahead of you. Stressful time. We're deffo going underfloor downstairs - reasons.. don't like the look of radiators, more even heat, OH likes the warm tile feel etc etc. Still not decided on the first floor. Might be as handy to put in UF but may not be used much.

Haven't seen too many say a bad word about HRV so would recommend that you research that anyway.

And get started on the window suppliers... long draw out process for us but we're finally getting there.

mr_edge_to_you · 14-07-2009 10:09pm

We've just kicked off 1 2100 sq ft house, almost finished sub floor. We're putting in ground source heat pump with UFH upstairs and downstairs.

From my relatively basic knowledge the issue you should be looking at is what source of heat are you expecting to use, not just radiator/UFH issue.

My research has shown to me that oil is very very expensive with UFH. UFH appears to be more suited to some of the newer renewable energy systems which give a more constant/ambient heat.

Best of luck with your build!

Mr Edge.

A country home · 14-07-2009 10:42pm

ill put a spanner in the works. . .
3rd option for you. . .

we are going for the tried and tested. . . rads. . .oil. . open fire (the later we both wont throw out)

anyway, , I wont say we didnt think about UFH/pumps etc. . .we consulted those who knew the business and also a few friends/friend of friends. . . . and from a personal exp we just decided for the usual way. .
but put everything we have into insulation. .
one thing we didnt want, which almost every told us you will loose and thats 100% control with UFH. . .
I have one guy working with me and i heard so many (its too hot, its too cold) . . i do know our temperatures are all over the place, great this day, cold that day. . and for UFH i just dont think this is for us. we are always looking for that quick flick of a switch and 15mins later hot rads. . .

in ref to the poster about not liking rads. . .well, all i can say is i know no different,, they haven been in almost every house in my 30 yrs. . so I guess they are like walls to me. . its just part of the building.. . lol. .

im sorry that we all here have different thoughts. . . but just make sure you go with whats happy with ye,
find out all info, talk to those in the know, best thing is to get honest people to comment on there own UFH. . ask yourself the pros and cons of each system. . .

hope this helps. .

Msmaloney26 · 14-07-2009 10:53pm

In the same boat lads with UFH vs rads....waiting to kick off build and pulling my hair out with which system is best. I am 80% now on selecting UFH but just have to research every thing....it is a pain with costs involved and all the different opinions you get.
I am looking at oil based system ...not most efficent/cost effective maybe....still researching air to water heat pumps.....best of luck!

Juantorena · 15-07-2009 9:36am

We've gone with UFH downstairs and have piped for alu rads upstairs with the hope that we won't need them (insulation levels, air-tightness, MHRV, etc.). Running off of ASHP.

Leadership · 15-07-2009 1:29pm

Just made the choice to to fit rads instead of UFH and pump the saving into insulation and alu rads. This was after consulting experts, people who have it and working out the physics of it.

The conclusion was a mix of rads and UFH between floors is a waste, all or nothting other wise the benifits of each cancel each other out and you have an uneconomical system.

ablelocks · 15-07-2009 2:22pm

mr_edge_to_you wrote: »

My research has shown to me that oil is very very expensive with UFH. UFH appears to be more suited to some of the newer renewable energy systems which give a more constant/ambient heat.
.

can you provide some links mr. edge? we were going to go with oil-fired boiler + radiators but our plumber is suggesting ufh as an alternative to the rads.

mr_edge_to_you · 15-07-2009 3:04pm

ablelocks wrote: »

can you provide some links mr. edge? we were going to go with oil-fired boiler + radiators but our plumber is suggesting ufh as an alternative to the rads.

unfortunately all my research on this was done the old fashioned way, on the streets! What we were told by contractors we got quotes from was the UFH doesn't lend itself to instant heat. For example, you're cold in the evening and you want to turn on the heat. With oil, rads will heat up instantly. UFH is much harder to heat as the heat has go through your screed and floor covering, therefore longer to get the temp up. To get proper heat out of UFH the heat needs to on for substantially longer, hence higher oil use. It really needs to be kept warm which would require more oil. If you use a heatpump it keeps a lower level of heat constant. That't about the best I can do, sorry.

bdoo · 15-07-2009 5:58pm

Thanks for all the replies,

I actually met a lad today about it, he recommended a thermal store heated by solar and topped up with oil heating when needed. Recommends room stats in each room and individual room zoning as opposed to upstairs /downstairs.

The thermal store is like your hot water tank but unlike the traditional system the water in the tank doesnt change and is always warm, UFH and Domestic H/W run in coils through the hot tank and take their heat from there when needed.

Think my mind is nearly made up...only thing is it's pricey enough!

xt40 · 15-07-2009 6:32pm

i would not be convinced about the thermal store idea heated by solar panels.
i very much doubt it would heat the water to the 40 ish degs that it will need to be.
if anybody tells you it will work at 25, they are talking rubbish as the house would NEVER warm up to a comfortable room temp
stats in each room would be normal in a ufh system
i have and would recommend using an oil boiler
the way it works is
stat sends signal to ufh control box to switch on heating and open a valve on whetever zone(s)
boiler fires and heats water to 65-70 degs
thermostatic valve (40degs) lets the hot water into the ufh system where it is mixed with the cold water ufh return and then sent down the ufh flow at 40 degs the excess boiler water can then be diverted to heat rads upstairs etc

ufh might be slow to heat up but it is also slow to cool down and a million times better than rads

bauderline · 15-07-2009 7:54pm

I went for the following configuration in a 6000 sq ft house with UFH on three floors.

UFH Manifold on each floor with each room connecting back to a different port.
Stats in each room connected back to an actuator on each port.
200,000 BTU Oil Condensing Boiler
12 sqm of solar panels on south facing roof.
TiSun ProClean Buffer Tank 800L

The oil boiler will charge the buffer tank and operate off a differential temp sensor then UFH will run off buffer tank via a thermostatic valve.

Connecting oil boiler directly to UFH is not a good idea, makes it very inefficient.

The idea behind UFH is to maintain a constant temp in your home and with a properly tuned system in a well insulated house it will do just that.

TiSun Combination Tank PDF (worth reading)
http://www.rvr.ie/datastore/brochures/TiSun%20combination%20tanks.pdf

My 2 cents...

A country home · 15-07-2009 8:47pm

xt40 wrote: »

ufh might be slow to heat up but it is also slow to cool down and a million times better than rads

for the person asking the question here, just take note of the sentence above.

I would nearly say your last line is why some people are so confused. .

I for one dont like this element of UFH, and I know that alot of poeple are not aware of it. .

just something to point out. .

bauderline · 15-07-2009 9:16pm

A country home wrote: »

for the person asking the question here, just take note of the sentence above.

I would nearly say your last line is why some people are so confused. .

I for one dont like this element of UFH, and I know that alot of poeple are not aware of it. .

just something to point out. .

... well ... you really do have to abandon the idea of the conventional heating system when you use UFH. With conventional rads it is true that you can fluctuate the temperature of the house much more quickly... but that begs an important question.... why on earth would you want to do that ?!

Why not maintain a constant ambient temperature in the home, never too cold, never too warm... just right... that is why the stats in every room are important.. so that you can control and maintain this ambient temperature accurately...

A country home · 15-07-2009 9:32pm

bauderline wrote: »

... well ... you really do have to abandon the idea of the conventional heating system when you use UFH. With conventional rads it is true that you can fluctuate the temperature of the house much more quickly... but that begs an important question.... why on earth would you want to do that ?!

Why not maintain a constant ambient temperature in the home, never too cold, never too warm... just right... that is why the stats in every room are important.. so that you can control and maintain this ambient temperature accurately...

our climate is not constant. temps up temps down. . . . .3pm in the day can be one temp, and by 8pm you wish you could boost up the UFH.

I will say, that your neither right nor wrong, . . . this has been going on for yrs. . . . its one persons view over anothers. . I know its not the last of it on this board. .

sydthebeat · 15-07-2009 10:48pm

A country home wrote: »

our climate is not constant. temps up temps down. . . . .3pm in the day can be one temp, and by 8pm you wish you could boost up the UFH.

I will say, that your neither right nor wrong, . . . this has been going on for yrs. . . . its one persons view over anothers. . I know its not the last of it on this board. .

the whole idea of energy efficiency is to trap delivered heat.

it is so much more economical to maintain a constant temp than to maintain a heat up - cool down system.

apparently contrary to belief, ireland certainly does not have wide temperature fluctuations.... we have a fairly even temperature scale ... approx 3 deg in winter to approx 24-25 in summer.... compare that to mid europe where averages can go from as low as -12 to mid 30s in summer....

steming from this ireland is actually more sutited to ambient heating systems such as underfloor heating than europe, where its use is widespread...

BnA · 15-07-2009 11:19pm

I would have to disagree with you syd and agree with country house.

We're building approx 2800 sqft 1.5 story bungalow.

Our initial plan was to go Geothermal / Underfloor. However we read so so many mixed reports about Geothermal that they, (along with the massive cost of drilling etc) turned us off it.

We then though we'd put in UFH in the downstairs and old fashioned rads upstairs and run it all off oil. OUr idea was that by putting in the UFH now downstairs, maybe in a few years when we had a bit of money and maybe more confidence in geothermal technology, we could switch over to it. But my plumber (who's a good friend) put me right off it. As he pointed out, yes, ufh keeps rooms at a constant ambient temp all day. But that is an awful waste of money in a bedroom where all you want is a quick blast of heat half an hour before you go to bed and maybe another blast in the morning.

So then we went to UFH in the living area only with another heat source (some kind of stove) to give the room a blast on an evening when it is unexpectedly cold and you don't have the ufh turned on. This was our plan for a long time.

But just today after talking to the plumber again and another friend who works in plumbing supplies, I am thinking we'll throw out the under floor altogether. We are gaining nothing from it. Yes the tiles might be nice and warm, but it will cost a fortune to run, be more expensive to install, and has much greater potential to give trouble in the future. If a Rad gives you trouble, the worst you'll have to do, is take it off the wall and replace it. If your UFH starts acting up, it could be out with the pick and shovel and down you go through the lovely marble tiles...

One bit of advice that I did get today though that I think is very well worth passing on. If you do decide to go for UFH (particularly if you go Geothermal as well) , be very very very careful about who you get to install it. There are an awful lot of cowboys out there. A bog standard rad type system can be repaired easily enough, but a poorly installed UFH system is nothing short of a total nightmare.

RE Syds point about Irelands Climate being suitable, I'd have to disagree. The Irish climate might not have as extreme temps as other parts of Europe, but we have much more flucuations on a day to day basis. That's what makes UFH unsuitable. In Ireland you often don't know if you will need the heating untill you get up in the morning or untill you get home in the evening. With UFH, that's too late.

sinnerboy · 15-07-2009 11:49pm

Many clients have told me - UFH - best thing ever . Others - never again .

Coffee or tea ? There is no universal answer.

Neither rads nor UFH ought to be more expensive . Simple physics .
Rads circulate less water at higher temp . UFH circulates more water at lower temp . The heat energy ( and fuel consumed ) in theory should be the same .

User behavior mucks it up however . Some never really adjust to UFH , turning it on too soon , off too late - once bitten twice shy by a cold snap . And then go about opening windows to dump heat ( and €€€'s ) on that "surprisingly" warm afternoon . Avoid this "trap" and UFH won't cost any more to run than rads .

15-07-2009 11:56pm

bauderline wrote: »

I went for the following configuration in a 6000 sq ft house with UFH on three floors.

UFH Manifold on each floor with each room connecting back to a different port.
Stats in each room connected back to an actuator on each port.
200,000 BTU Oil Condensing Boiler
12 sqm of solar panels on south facing roof.
TiSun ProClean Buffer Tank 800L

The oil boiler will charge the buffer tank and operate off a differential temp sensor then UFH will run off buffer tank via a thermostatic valve.

Connecting oil boiler directly to UFH is not a good idea, makes it very inefficient.

The idea behind UFH is to maintain a constant temp in your home and with a properly tuned system in a well insulated house it will do just that.

TiSun Combination Tank PDF (worth reading)
http://www.rvr.ie/datastore/brochures/TiSun%20combination%20tanks.pdf

My 2 cents...

Very similar to my system, 100% happy with it.

sydthebeat · 15-07-2009 11:57pm

BnA wrote: »

But that is an awful waste of money in a bedroom where all you want is a quick blast of heat half an hour before you go to bed and maybe another blast in the morning.

So then we went to UFH in the living area only with another heat source (some kind of stove) to give the room a blast on an evening when it is unexpectedly cold and you don't have the ufh turned on. This was our plan for a long time.

But just today after talking to the plumber again and another friend who works in plumbing supplies, I am thinking we'll throw out the under floor altogether. We are gaining nothing from it. Yes the tiles might be nice and warm, but it will cost a fortune to run, be more expensive to install, and has much greater potential to give trouble in the future. If a Rad gives you trouble, the worst you'll have to do, is take it off the wall and replace it. If your UFH starts acting up, it could be out with the pick and shovel and down you go through the lovely marble tiles...

One bit of advice that I did get today though that I think is very well worth passing on. If you do decide to go for UFH (particularly if you go Geothermal as well) , be very very very careful about who you get to install it. There are an awful lot of cowboys out there. A bog standard rad type system can be repaired easily enough, but a poorly installed UFH system is nothing short of a total nightmare.

RE Syds point about Irelands Climate being suitable, I'd have to disagree. The Irish climate might not have as extreme temps as other parts of Europe, but we have much more flucuations on a day to day basis. That's what makes UFH unsuitable. In Ireland you often don't know if you will need the heating untill you get up in the morning or untill you get home in the evening. With UFH, that's too late.

we'll agree to disagree....

need a 'quick blast' is an auld oirish way of thinking. The whole point of a high level of insulation and air tightness is there is always a constant temperature....
is it more efficient to keep a room at 18 degrees all day or to heat it from say 14 deg to 21 deg twice a day.... well, if you have taken all teh measures to reduce heat loss, it is more efficient to keep the room a constant temp.

we are so used to very very bad standards of construction we are programmed into assuming the worst. We close doors to keep the heat in rooms, while our european friends leave doors open (or open plan living) to encourage the free movement of heat currents throught the house...
Its simply a mindset we need to get out of. Yes, we are right to be wary of construction standards.... but that shouldnt mean we cannot demand the best!

again, the argument that in ireland 'sure, we dont know one day from another what the weather will be life'... doesnt cut it. The effect of temperature fluctuations outside are minimised with a high level of insulation and air tightness.. and im not talking about current regulation standards! Middle europe can see temp swings in spring and autumn from say -5 at night to 24 during the day (approx a 30 deg swing)..... the most we see would be from say 5 to 15 (or a 7-10 deg swing)... This would negate your argument about our unsure weather. Its actual an indictment on our construct standards that such a low temperature swing can have such an effect on our comfort of living!!

the rate of heat loss depends on three main factors:
1. the temperature differential between inside and outside.
In every case europeans have a higher temp differential
2. the level of insulation... obvious
3. the level of air leakage... we call this air tightness.

16-07-2009 12:00am

sydthebeat wrote: »

the whole idea of energy efficiency is to trap delivered heat.

it is so much more economical to maintain a constant temp than to maintain a heat up - cool down system.

apparently contrary to belief, ireland certainly does not have wide temperature fluctuations.... we have a fairly even temperature scale ... approx 3 deg in winter to approx 24-25 in summer.... compare that to mid europe where averages can go from as low as -12 to mid 30s in summer....

steming from this ireland is actually more sutited to ambient heating systems such as underfloor heating than europe, where its use is widespread...

I tend to agree with this, I have my system set up to run about three hours in the morning and five in the afternoon/evening, the thermostatic mixer valve is set to 35C and I never find any cold spots.

But most importantly I have the house very well insulated & MHRV installed!

bauderline · 16-07-2009 12:09am

I would say a lot of the negative reports on UFH are from people with poorly installed/configured systems and/or poorly constructed houses.

syd sort of touched on this, but a well insulated and air tight house should protect the interior temperature of the house from rapid exterior temperature fluctuations providing more than enough time for the UFH system to react.

I contend strongly that a properly installed and configured UFH system in a suitably constructed house will provide a far superior living environment than a rad based system.

... ok I see syd has posted again in the meantime... saying the same thing but better....

BnA · 16-07-2009 12:11am

sydthebeat wrote: »

we'll agree to disagree....

...is it more efficient to keep a room at 18 degrees all day or to heat it from say 14 deg to 21 deg twice a day.... well, if you have taken all teh measures to reduce heat loss, it is more efficient to keep the room a constant temp.

I'm very sceptical about this.

If you have two rooms with the same level of air tightness/insulation etc I do not believe that it would use less energy to keep the room at a constant temp of 18 degrees, 24 hours a day than it would be to turn on a rad for 1.5 hours in the day.

Also, a good UFH system requires a high level of air tightness in a house and I am certainly not convinced that this is healthy. I know you can use heat recovery units to change the air in the house for you while utilising the heat in the air you are extracting, but you are looking at an awful lot of expense when you combine this with the cost of the UFH system.

bauderline · 16-07-2009 12:31am

1.5 hours a day !!??

That would seem a bit on the low side... however taking into account that both rooms are equally well insulated and air tight then I would question if the UFH in that room would be activated much longer than 1.5 hours. Don't forget the screed acts like a giant storage heater so it will give off heat long after a radiator has cooled down. Also take into account the much lower temperature the UFH operates at which means less energy used as well..

The one thing I will give you is that the more time you spend in the house the greater the return you will get from UFH.

A pet hate of mine in rad based systems is the shutting down of the heating system before going to bed. In the middle of winter the house gets really cold during the night... any trips to the loo and the words "... I may be gone for some time" spring to mind...

BnA · 16-07-2009 12:20pm

bauderline wrote: »

1.5 hours a day !!??

That would seem a bit on the low side... however taking into account that both rooms are equally well insulated and air tight then I would question if the UFH in that room would be activated much longer than 1.5 hours. Don't forget the screed acts like a giant storage heater so it will give off heat long after a radiator has cooled down. Also take into account the much lower temperature the UFH operates at which means less energy used as well..

The one thing I will give you is that the more time you spend in the house the greater the return you will get from UFH.

A pet hate of mine in rad based systems is the shutting down of the heating system before going to bed. In the middle of winter the house gets really cold during the night... any trips to the loo and the words "... I may be gone for some time" spring to mind...

Yeah..... I might have been a bit optimistic with my 1.5 hours a day.

After doing my research on the net and spending a lot of time talking to people in the trade / building houses themselves etc over the last few years, I am about 2 weeks away from putting in the first fixing of my plumbing, and I'm still not 100% sure what I will go for. The only 100% definate conclusion that I have come to is that there are a lot of confliction reports out there and there is a lot of mis-information out there.

On one hand, I feel there are a lot of people who are pushing a green agenda and who latch onto a particular system because it is being marketed as the next big green thing without actually doing genuine research into it.

Then, you will have a lot of people who will dismiss systems because they are too expensive without actually looking into the long term payback on the system.

Also, as mentioned a few times on this thread, a lot of new technologies, get a bad name because they were just poorly installed.

All in all, I found it is very very difficult to cut through all the bull that is out there to get down to the hard facts and try and see what is the best genuine system for your house.

sydthebeat · 16-07-2009 12:29pm

BnA wrote: »

Yeah..... I might have been a bit optimistic with my 1.5 hours a day.

After doing my research on the net and spending a lot of time talking to people in the trade / building houses themselves etc over the last few years, I am about 2 weeks away from putting in the first fixing of my plumbing, and I'm still not 100% sure what I will go for. The only 100% definate conclusion that I have come to is that there are a lot of confliction reports out there and there is a lot of mis-information out there.

On one hand, I feel there are a lot of people who are pushing a green agenda and who latch onto a particular system because it is being marketed as the next big green thing without actually doing genuine research into it.

Then, you will have a lot of people who will dismiss systems because they are too expensive without actually looking into the long term payback on the system.

Also, as mentioned a few times on this thread, a lot of new technologies, get a bad name because they were just poorly installed.

All in all, I found it is very very difficult to cut through all the bull that is out there to get down to the hard facts and try and see what is the best genuine system for your house.

bna... i completely agree that theres a huge amount of conflicting advice out there...

in regard to your situation i would put the decision like this...

are you incorporating a MHRV system...??

If no, i wouldnt go with an UFH system...

If yes, the viability of an UFH system is GREATLY increased...

Juantorena · 16-07-2009 12:48pm

BnA wrote: »

Yeah..... I might have been a bit optimistic with my 1.5 hours a day.

After doing my research on the net and spending a lot of time talking to people in the trade / building houses themselves etc over the last few years, I am about 2 weeks away from putting in the first fixing of my plumbing, and I'm still not 100% sure what I will go for. The only 100% definate conclusion that I have come to is that there are a lot of confliction reports out there and there is a lot of mis-information out there.

On one hand, I feel there are a lot of people who are pushing a green agenda and who latch onto a particular system because it is being marketed as the next big green thing without actually doing genuine research into it.

Then, you will have a lot of people who will dismiss systems because they are too expensive without actually looking into the long term payback on the system.

Also, as mentioned a few times on this thread, a lot of new technologies, get a bad name because they were just poorly installed.

All in all, I found it is very very difficult to cut through all the bull that is out there to get down to the hard facts and try and see what is the best genuine system for your house.

Not to derail the thread but have to agree with you, BnA. I have agonised (yes, literally!) over the heating system/method(s) for the house and finally came to these realisations: you'll never get the 'perfect' system; what you do go with will be outdated in 3-5 years time and your own personal circumstances/habits will determine the eventual success or otherwise of your choices.

At some point you need to draw a line and - with an informed, if that's possible, mindset - just go with your instincts. I am wide open to the possibility of getting the heating mix wrong...whether or not we enjoy the house will be the ultimate determinant of success or 'failure' for me.

What I would say though is that, as has been said on here many a time, there are ways to reduce how 'wrong' you get it...reduce the heating requirement int'-first place!

NextSteps · 16-07-2009 1:09pm

Just from personal experience - we have UFH downstairs and rads upstairs (bedrooms which don't need to be heated except morining and for an hour in the evening). For us, UFH would be a total waste upstairs - about 22 hours a day of unneeded heating.

But downstairs, we've found it to be very good, constantly the heat has been just about right. Over the last year or two, we've occasionally opened windows to adjust the heat (in spring, when we weren't ready to turn the heat off altogether), and occasionally lit a fire - but that was for atmosphere, not comfort. Plus, we haven't been always closing doors to keep the heat in whichever room we're in, as you might with a rad system.

People are always saying how warm and cosy the house is, and I love the warm tiles and floorboards. (So does the cat.)

In terms of cost, I'm not sure - there have been so many other variables since we changed the house (solar panels, insulation, new gas boiler) that I can't measure the difference in our bills.

Hope this helps.

sinnerboy · 16-07-2009 1:26pm

BnA wrote: »

If you have two rooms with the same level of air tightness/insulation etc I do not believe that it would use less energy to keep the room at a constant temp of 18 degrees, 24 hours a day than it would be to turn on a rad for 1.5 hours in the day.

2 identical rooms one Rads , one UFH will require the same energy to achieve the same temp . Simple law of physics .

16-07-2009 2:03pm

sinnerboy wrote: »

2 identical rooms one Rads , one UFH will require the same energy to achieve the same temp . Simple law of physics .

True over a 24 hour period, except that the radiator is on for only 1.5 hours of the day that room will experience a large tepmerature variation, the UFH (with a concrete floor) will easily maintain the same temperature.

kkhurler · 16-07-2009 2:34pm

When we put in UFH we were sold it as a way of life rather than a heating system and i think that this adequately reflects exactly what it is. you dont turn it on and off you have min and max temperatures and this is how to best regulate it - however if you have a warm day and snow the next UFH is not that adaptable - it takes a while to get rooms to required comfortable temp. i wouldnt change it - but if i had smaller rooms i would look more favourably on radiators.

Underfloor Heating

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