Are there any downsides to water UFH?

indus · 4 Oct 2012

Since water UFH can be fitted underneath virtually any floor (though not that effective under carpet) is there any reason not to use it rather than conventional radiators?

The pros are obviously more even heat distribution and therefore more comfortable heat and saving space.

Are there any downsides?

Thanks

rego · 4 Oct 2012

big downside if you get a leak under your expensive tiled floor

dcawkwell · 4 Oct 2012

More expensive to fit.
Can be very very slow to respond therefore has to be left on long periods
or virtually all the time.
Replaced a boiler in a house with underfloor downstairs radiators upstairs.
30-60 minutes upstairs was warm and fine.
Downstairs 2-3 hours still no effect and still freezing. No thank you.

Can't lean against a nice warm radiator and warm your backside.

Agile · 5 Oct 2012

UHF is fine in libraries and old peoples homes and retired people as well I expect.

But its slow to warm up and slow to cool down.

I stayed somewhere with it in all rooms. I had to go to sleep with the duvet rolled back and then wake up feeling cold at 3 am to retrieve it.

Not my idea of comfort. Rads in contrast cool down in 20 min and switching off the heating as I start to go to bed means its well cooled before I get into bed.

I rather like sleeping with a part open window so its more like 12 C at night. Then I can get cuddled more by a size 16 !

Tony

indus · 5 Oct 2012

Thanks.

Not what I was expecting to hear, I thought UFH was the way to go. Slow response times both off and on would not be good for me, I get hot very quickly at night.

I'll probably scrap that idea and stick with radiators then for the majority of the house.

I'd still quite like UFH in the bathrooms and perhaps kitchen though. Would you guys suggest a water based system for this or electrical (as most people seem to do)

Thanks

Agile · 5 Oct 2012

Electric in bathrooms is more expensive to run but does not suffer much from the time lag because the element can be just below the tiles.

I would never want UFH in a cooking kitchen because cooking heat means the temperature varies greatly. The room is also only used for short periods of time so UHF is wasteful.

In fact I prefer the plinth fan heaters as they respond very quickly!

Tony

indus · 5 Oct 2012

Thanks Tony.

Electric in bathrooms then.

In terms of the kitchen mine is a 'live in' kitchen with the family room/snug open plan to it. As such (and because I eat and drink too much

) it means it's one of the most used parts of the house.

It has rads in it already which work fine but sometimes first thing in the morning it would be nice for the floor to be warm. The floor is going to be ripped up and retiled quite soon so I thought I might take the opportunity for ufh.

It's probably particularly cold because I have a suspended floor with about four foot high space underneath which has no insulation. I didn't think of insulation when I had the floor originally tiled about 7 years ago. When I redo the tiles I could also use the chicken wire thing to insulate it.

Thanks

Agile · 5 Oct 2012

My recommendation would still be to add insulation under the floor. That can make an amazing difference to the comfort level.

The urethene foam is probably best although fibreglass would be cheaper although I would probably fix it with thin wooden battons rather then chicken wire which is difficult to fix as well as being very expensive now.

Tony

vv2806 · 5 Oct 2012

Agile said:
The room is also only used for short periods of time so UHF is wasteful.

Tony

You might not believe it but some people are actually cooking

Sorry, I just couldn't miss the opportunity

On a serious note, thank you for all the comments, I am going to bookmark the topic as a very useful one.

Agile · 5 Oct 2012

vv2806 said:
Agile said:

The room is also only used for short periods of time so UHF is wasteful.

Tony

Click to expand...

You might not believe it but some people are actually cooking

Exactly so! The cooking adds serious heat and the room needs to be extract ventilated to cool it down!

The accumulated stored heat in the UFH is then totally wasted!

indus · 6 Oct 2012

Thanks.

What causes this slow response time? And what can be done to limit it?

vv2806 · 6 Oct 2012

indus said:
Thanks.

What causes this slow response time? And what can be done to limit it?

The law of physics, I imagine. On top of the hot pipes/cables you would put some solid materials - screed, timber, tiles, tile adhesive - depending on the floor covering. None of these materials is a good heat conductor, so it takes time to raise their temperature and to allow the air in the room to be heated.

indus · 6 Oct 2012

vv2806 said:
indus said:

Thanks.

What causes this slow response time? And what can be done to limit it?

Click to expand...

The law of physics, I imagine. On top of the hot pipes/cables you would put some solid materials - screed, timber, tiles, tile adhesive - depending on the floor covering. None of these materials is a good heat conductor, so it takes time to raise their temperature and to allow the air in the room to be heated.

Thanks.

But then why don't we see this poor response time with electrical ufh? Is it because the electrical heating element reaches a much higher temp than the water in a ch system and so the floor rises in temp quicker?

ALEC1 · 6 Oct 2012

a zone of UFH is an established way of increasing system efficiency but only with compensation valves that ensure the right amount of heat is introduced into the zone at any one time..

The valves sold in the UK generally require a flow of around 70c..where as a compensated valve on a compensated unmixed circuit, will be operating at about 28c or lower

The other thing to avoid is wooden surfaces...there is no efficiency gain with UFH under wood...you have to run it at such a high temperature to over come the thermal resisitivity...you might just as well install radiators...on a compensated heating citcuit obviously...

indus · 6 Oct 2012

Thanks Alec but you have lost me with the 'compensation valves', what exactly do they do?

And if these valves resolve the issue of slow response time then why doesn"t everybody fit them and avoid the problem?

Thanks

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Are there any downsides to water UFH?

ALEC1

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