Under floor heating with piped water system

Maz1963

Has anyone any experience of this? I'm looking to buy a new build which has this system.  I don't have an issue with it as such, but it's a new concept to me and I noticed that there are vents in the ceilings which they recommend should stay on all the time.   They didn't say this, but I assume there are potential condensation issues with this type of heating if the water in the pipes gets too cold.  Would be grateful for any feedback from anyone who has this type of heating system in their home. Many thanks!

Robin9

What heats the water - if electric be aware of high running costs.

Maz1963

Thanks for responding Robin.  The water is heated by a gas boiler.

Cardew

https://www.ovoenergy.com/guides/energy-guides/pros--cons-of-underfloor-heating.html

dunstonh

We have underfloor heating in part of the house and no issues with condensation.  At the end of the day, the water isn't leaving the system.  So, no evaporation occurs.   The tiles heat up and heat rises.     Air circulation is important with many types of heating and house.    Maybe the vents aid that circulation.     Especially if the house is well insulated.   

Mickey666

This^^^
We have ‘wet’ underfloor heating in part of our house.  There is no more issue with condensation than there is with an ordinary radiator because that’s basically what it is, except the water is circulating within the floor slab rather than circulating within a metal radiator.

The air vents will be nothing to do with the UFH (we don’t have any).

Gerry1

Cardew said:

https://www.ovoenergy.com/guides/energy-guides/pros--cons-of-underfloor-heating.html

Some of that Ovo review sounds like it's written by the Magic Dust radiators people ! Some claims are at least questionable:-

• A suitably sized unit can heat a larger area than an individual radiator, and works at a lower temperature, so it could reduce your heating bills
• Less wastage – your floors will stay warm even if the windows are open or the room is very draughty
• It might enhance your home’s selling price: underfloor heating has a reputation for being state of the art and high spec and could attract buyers looking for a luxurious property

Cardew

Gerry1 said:

Cardew said:

https://www.ovoenergy.com/guides/energy-guides/pros--cons-of-underfloor-heating.html

Some of that Ovo review sounds like it's written by the Magic Dust radiators people ! Some claims are at least questionable:-

• A suitably sized unit can heat a larger area than an individual radiator, and works at a lower temperature, so it could reduce your heating bills
• Less wastage – your floors will stay warm even if the windows are open or the room is very draughty
• It might enhance your home’s selling price: underfloor heating has a reputation for being state of the art and high spec and could attract buyers looking for a luxurious property

OVO do not have a vested interest and IMO the statements are valid.

1. Running a modern condensing boiler at lower temperatures is more economical.

2 Wastage - why is that not a valid point

3. Selling price - ditto?

Mickey666

1. UFH runs at a lower temperature because the surface are of the ‘radiator’, ie the floor itself, is very large.  If wall-hung metal Radiators were just as large then they could be run cooler as well for the same heating effect. Nothing to do with condensing boilers.  Basic physics dictates that a certain room volume with certain insulation properties will require the same energy (heat) input to maintain a given temperature regardless of the energy source.

2. UFH cannot reduce heat wastage if the windows are open.  Yes, the floor may remain warm, but that’s nothing to do with heat wastage.
3. Purely speculative.

Talldave

I like underfloor heating but you can't use it like radiators because it runs at a lower temperature and so takes longer to warm the place up. How is it zoned? The place we're renting has a thermostat per room, which is nice. But if you're using thermostats with ""optimum start" ie: I want 21C at 8am, you need one that can cope with having to kick in hours ahead rather than minutes ahead.

Mickey666

Talldave said:

I like underfloor heating but you can't use it like radiators because it runs at a lower temperature and so takes longer to warm the place up.

Yes and no.  It's not because it runs at a lower temperature that it takes longer to heat up (and cool down), it's because of the huge thermal mass of the floor slab.  It's a bit like a very large storage heater in that respect.

You're right about having to anticipate this 'thermal lag' when setting timers and thermostats and UFH may not be idea for people whose houses are empty all day and only want a quick burst of heat for an hour in the morning (for example).

Personally, I love our UFH, but then the house is never empty for long periods so it works fine for us.