Underfloor Heating - Good Idea? Bad Idea?

rus2007

Any advice on underfloor heating from people who have recently installed it?

We are at budgeting stage and were all set on UFH, but from speaking to a plumber recently he has got us thinking.
The plumber has advised us NOT to install it as he feels it is not suited to Ireland climate / weather patterns as it takes too long to heat up / cool down and can't just give a quick burst of heat on a cold day when it could be sunny again the day after.

Also - how economical are they vs. rads? I know they use less energy to heat per hour than rads as they are at a lower temp but if you have to leave them on much longer then is this benifit lost?

We will be installing a Condensing Gas Boiler for UFH and solar panels for DHW.

Our current house has rads and our usage pattern is to have them come on for an hour in the morning, off all day and then come on again an hour before we are due to come home - there is no point heating an empty house during the day when it's empty.

We are south facing, and installing triple glazed window and HRV system and LOADS of insualtion - with UFH running off thermostat should the temp be fairly regualted?

Sorry for long list of questions etc but big difference in price of rads vs UFH and it's not exactly something we can but in after - so want to make sure we doing the right thing.

sinnerboy

some love it some don't

you have to "get used" to it - it heats up and cools down slowly

that p*****s some off but not all

a secondary means of heating ( say gas fireplace ) may solve requirement for quick blast of heat . high and low level windows for fast ventilation / cooling if you occasionally overheat

no rads can give a terrific freedom when it comes to laying our furniture

cost is neutral to run - each method if designed and installed correctly will demand the same fuel load to heat the house

rus2007

Thanks!

We will probably install WP stove in main living area and log stove in other sitting room for addiotnal heat if required and as you say - if too hot we can always open windows!!

ircoha

rus2007 wrote: »

Thanks!

We will probably install WP stove in main living area and log stove in other sitting room for addiotnal heat if required and as you say - if too hot we can always open windows!!

open windows and in another thread you are hell bent on airtight house with HRV.

Perhaps a case for what PWC call joined up thinking, or at least joined up threads:)

Make sure the stoves will work with HRV

Builderfromhell

You might consider fan assisted radiators (Solo). Smaller rads, less of them, rapid heat up and use less fuel.
Combination boiler a good idea. Not suited to UFH though. Heats water to high temp. which then has to be mixed with cold water for lower temp. in UFH. Boiler life reduced. Your plumber might explain in detail.
I have been asked to install UFH several places and clients always sorry they put it in. Cannot predict tomorrows temp. but UFH needs to be on in advance of heating house.

sinnerboy

ircoha wrote: »

open windows and in another thread you are hell bent on airtight house with HRV.

Perhaps a case for what PWC call joined up thinking, or at least joined up threads:)

Make sure the stoves will work with HRV

thinking is more than joined up

air tightness and hrv are to prevent heat loss through uncontrolled and/or unintended air paths

highly insulated buildings can overheat in summer OR in mild winter days with UFH with slow cool down period - a logical response is high and low level opening windows

if stoves are fitted into ( OP see PM ) chimney system then they will work with HRV

sinnerboy

Builderfromhell wrote: »

You might consider fan assisted radiators (Solo). Smaller rads, less of them, rapid heat up and use less fuel.
Combination boiler a good idea. Not suited to UFH though. Heats water to high temp. which then has to be mixed with cold water for lower temp. in UFH. Boiler life reduced. Your plumber might explain in detail.
I have been asked to install UFH several places and clients always sorry they put it in. Cannot predict tomorrows temp. but UFH needs to be on in advance of heating house.

Properly engineered , boiler will work fine with UFH . not contradicting your experience BFH - just contrasting with my own

As I say - some clients are sorry they went with UFH - others love it ( with boilers )

ircoha

sinnerboy wrote: »

thinking is more than joined up

air tightness and hrv are to prevent heat loss through uncontrolled and/or unintended air paths

highly insulated buildings can overheat in summer OR in mild winter days with UFH with slow cool down period - a logical response is high and low level opening windows

if stoves are fitted into ( OP see PM ) chimney system then they will work with HRV

Just goes to show one is never too old to learn.
Thanks for the insight SB, it certainly presents another dimension to be considered when looking at UFH

blast05

Have just installed UFH in big open plan area in new house - love it and i never even considered the benefits of not having ugly rads hanging off the walls (even if they are covered). Have a big stove for the quick blast of heat. It took me a few months to be able to set the thermostats to the temps that suited - trial and error. Since then we very rarely are too hot or cold

Just had our first season with UFH (running from an oil boiler via a heatbank/thermal store), I have set the mixing thermostat to 35c (it's lowest setting). Having the UFH set this low virtually eliminates the risk of overshoot, downside is that raising the temperature in any room is very slow.

I am very happy with the results, It took a couple of days to bring the house up to temperature the first time (fabric stone cold) then it stayed constant ever since.




the graph shows internal temperature & external temperature, I currently have the heating on for two hours in the evening & four in the morning.

The only two problems I had was the bathrooms overheating brecause I never fitted a thermostat to this circuit, I have just fitted one (last week!), problem solved.
The other is as I am using MHRV the air is moved around the house and if the bedrooms are set to a lower temperature that the bathrooms (wet areas) then the rooms are effectivly heated by the exhaust air from the bathrooms, the heating desn't come on and the missus complains the the floors are cold!

sas

Deleted User wrote: »

Just had our first season with UFH (running from an oil boiler via a heatbank/thermal store), I have set the mixing thermostat to 35c (it's lowest setting). Having the UFH set this low virtually eliminates the risk of overshoot, downside is that raising the temperature in any room is very slow.

I am very happy with the results, It took a couple of days to bring the house up to temperature the first time (fabric stone cold) then it stayed constant ever since.




the graph shows internal temperature & external temperature, I currently have the heating on for two hours in the evening & four in the morning.

The only two problems I had was the bathrooms overheating brecause I never fitted a thermostat to this circuit, I have just fitted one (last week!), problem solved.
The other is as I am using MHRV the air is moved around the house and if the bedrooms are set to a lower temperature that the bathrooms (wet areas) then the rooms are effectivly heated by the exhaust air from the bathrooms, the heating desn't come on and the missus complains the the floors are cold!

Don't suppose you could elaborate on how many litres of oil you used and over what period?

sas

sas wrote: »

Don't suppose you could elaborate on how many litres of oil you used and over what period?

Approx 800litres September to end February, A bit higher than hoped but I still had some incomplete insulation in the attic for most of the winter(since been finished).
I had the whole thing set too warm (missus wants lots of heat!:( ) have recently managed to drop it a couple of degrees, the temperatures were originally 22c throughout, way too warm. Now it's 18c in the bedrooms 20 in kitchen & livingroom(where the sensor is).
Plus a minor oil leak!!!

d2ww

Interesting information, Dolanbaker, I am hoping to keep rads in the old part of my house and ufh in the new part, so an oil boiler seems to be the way to go. Would you mind elaborating on how your system is set up, is the heatbank/thermal store simply a large immersion tank would in turn feeds the ufh circuit.
Thanks for the info,
d2ww

sunnysoutheast

hi rus2007

we've had underfloor in since November - we have an open plan house and marble floors

we bumped up window spec., insulation etc. and have HRV, we also have two Nestor Martin solid fuel stoves for point heating

we have the UFH on 24x7 on c.15-17 degrees, so it never really gets hot but never cools down either, however you often find the kids lying down on the floor playing! We have two condensing boilers - one runs the UFH the other the water and rads upstairs.

as regards response time remember there's two ways to install - under the slab or on top of it

our gas bill is about €11 a week for a 450m2 house

cheers
SSE

Hi sse

Just curious, how do you controll the UFH in the rooms with the stoves.
I had a minor issue with the bathroom & en-suite overheating and stopping a couple of bedrooms from ever coming on and ending up with cold floors.
I resolved it with an extra thermostat & loop valve actuator.

sunnysoutheast

hi db

We only have UFH downstairs, on its own boiler.

We have three zones in the main living area, plus another four (I think) zones - the 'stats are on the other side of the room/space from the stoves and away from HRV outlets.

One doh! moment was when we located a 'stat under a GU10 wall light on a sunny wall, that's the only misplaced one I think we have, during the summer I'll move it round the corner.

SSE

cotton

We installed UFH on 2 floors a couple of years ago with thermostats in every room except the bathrooms. Downstairs is fine but upstairs bathroom gets quite hot. We use gas for heating & the bills aren't that bad.
Only problem I have with it is the wooden floors in the sittingroom are warped from it.

cotton

cotton wrote: »

Downstairs is fine but upstairs bathroom gets quite hot.

See my post #15 above, the bathroom needs a thermostat & actuator as well (low voltage or remote sensor)

bauderline

Folks,

I assume there is nothing preventing me from putting an actuator on each "loop" on the manifold and corresponding thermostat in each room.

Is is possible to have every room on a separate loop on the manifold ?

The other question I wanted to ask is why the dual tariff is recommended. I know the UFH has a 2 hour run up / run down time with the 75mm screed which is fine for the morning but what about if you want to run it for another 2 - 3 hours in the evening, which is well likely in deep winter.... Does the dual tariff not make the day time consumption more expensive ?

b.

sinnerboy

bauderline wrote: »

Folks,

I assume there is nothing preventing me from putting an actuator on each "loop" on the manifold and corresponding thermostat in each room.

Is is possible to have every room on a separate loop on the manifold ?

The other question I wanted to ask is why the dual tariff is recommended. I know the UFH has a 2 hour run up / run down time with the 75mm screed which is fine for the morning but what about if you want to run it for another 2 - 3 hours in the evening, which is well likely in deep winter.... Does the dual tariff not make the day time consumption more expensive ?

b.

i always specify each room as a separate zone - each having a room stat

dual tarrif is advisable with heat pump , which runs on electricity . in this case the slim "easi screed" is not clever , you want to build up heat lowly ( cheaply on night rate ) through a MIN 75 screed , possibly even 100mm .

bauderline

Sorry,

My original question wasn't clear. I really meant to ask about the dual tariff on the heat pump...

Are you saying that by running it all night the 75mm screed will store enough heat to keep the house warm the entire day ?

Does the dual tariff not make any electricity consumption during the day dearer ?

Can I ask what do other people who have Geotherm do ? What times of the day do they run it ?

B.

joey1

rus2007 wrote: »

Any advice on underfloor heating from people who have recently installed it?

We are at budgeting stage and were all set on UFH, but from speaking to a plumber recently he has got us thinking.
The plumber has advised us NOT to install it as he feels it is not suited to Ireland climate / weather patterns as it takes too long to heat up / cool down and can't just give a quick burst of heat on a cold day when it could be sunny again the day after.

Also - how economical are they vs. rads? I know they use less energy to heat per hour than rads as they are at a lower temp but if you have to leave them on much longer then is this benifit lost?

We will be installing a Condensing Gas Boiler for UFH and solar panels for DHW.

Our current house has rads and our usage pattern is to have them come on for an hour in the morning, off all day and then come on again an hour before we are due to come home - there is no point heating an empty house during the day when it's empty.

We are south facing, and installing triple glazed window and HRV system and LOADS of insualtion - with UFH running off thermostat should the temp be fairly regualted?

Sorry for long list of questions etc but big difference in price of rads vs UFH and it's not exactly something we can but in after - so want to make sure we doing the right thing.

Go for underfloor heating im building my own house and installing it on the 1st floor also, it gives you loads of freedom on furniture placing etc, also if you install a screed from floor screed solutions you can put the screed in at 35mm which gives you better control over your temperature, ie less thickness, enables floor to heat up quicker and also cool down quicker.

slavetothegrind

Just a word on these thin screeds,
We were installing some equipment in a new shopping centre where the finished floors were poured using approx 70 mm of this liquid screed product, i'm not mentioning the company, but after it set it had the strength and consistancy of old cheese. You could literally dig it up with a spoon.
No doubt it was not layed properly but if they can get a massive floor area in an industrial context for a very large well known client wrong it doesn't bode well for the self buiders out there!
I am not aware of compensatory outcomes, the floors were not redone as the shops had all been fitted out.
The problem was with floor coverings laid on this. Adhesion was not possible and it was damaged extremely easily.
I guess be carefull out there!!

sculptor

There is a kit for floors under 18sq.m by a well known company that mostly do pipes and fittings. Has anyone any experience of it.
I'm thinking of using it in our little kitchen extension.