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Underfloor heating

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Former Member06/02/2022 21:00:22
1085 forum posts

[This posting has been removed]

DMB06/02/2022 21:19:09
1354 forum posts
1 photos

Hi Bill

The system that I have seen, consisted of a "trench" in the concrete floor of the offices, running around just below the windows adjacent to the exterior walls. In the "trench" were two copper pipes, 15mm dia.(?) with square copper fins attached, possibly 1. 1/2" or 2" square(?) maybe 1. 1/2" ? apart. Top of "trench" covered with fancy patterned Ali grating until the pikeys broke in and knicked it after the building was left vacant for a few months. Whether that design is common or not, I've no idea.


HOWARDT06/02/2022 21:23:47
932 forum posts
39 photos

Some people are not too enamoured with underfloor heating, I think it would be better in a new build with proper insulation under it, otherwise you will be heating the ground. All types of heating and insulation need to take a lot of factors into consideration in order to compare them. One type will best suit your house so don’t just think that because someone in your street swears by something that it will fit with yours.

Robert Atkinson 206/02/2022 21:33:26
1245 forum posts
20 photos

A little context would help
I assum you are talking heatpumps. Generally, yes underfloor heating heats the floor to warm underfoot and that heats the ret of the room.
We have electric underfloor heating in two areas of the house and it works well. Main heating is air-air heat pump (2 outdoor units 5 indoor) that alos pprovides air conditionng in summer.
The house was built witth "ceiling heating". This comprised foil heating elements behind the plasterboard forming the ceilings. No it does not work heat rises and white ceilings don't radiate well. The previous occupants had resorted to portable heaters....
Air-Air heat pumps are great but you don't get a grant for them because of the airconditioning capability.

I'm not sure about air-water ones when keeping existing radiators. The radiators were designed to work with hotter water than the heat pumps can create efficiently. Using underfloor heating with them seems much more reasonable. Lower temperature but larger surface area for same energy.
One disabvantage is you could loose a bit of headroom due to the thickness of pipes and insulation required.

Robert G8RPI.

Nick Welburn06/02/2022 21:43:19
134 forum posts

We have it, it’s basically just making the floors into a big radiator. Obviously lower temp otherwise you’d cook everything.

Takes a little time to get used too. First year we left the wrapped up xmas chocolate under the tree on the carpet

pgk pgk06/02/2022 21:45:47
2605 forum posts
293 photos

When my old Dad designed and built his bungalow in the early '60's, central heating wasn't common. He routed all the pipework underfloor to the rads, which was neat and quite nice to have areas of warm floor. Inevitably, settlement lead to a couple of leaks which damaged an area of parquet before being obvious.


Emgee06/02/2022 21:50:48
2445 forum posts
291 photos


Yes the floor will be warm to touch, it has to be in order to produce the heating effect.

Many years ago I was installing a lattice of resistive heating cables that were directly encased in the 2" thick floor screed.
The same system is still being used in some installations that of course use off peak electricity, the floor screed heats up during the charge period and emits the heat during the power off time, in some cases when you got to the evening when using the room all the heating effect had been used so you needed an additional heat source.

Most underfloor heating currently used is the wet system where loops of ususlly high temp plastic tubing is buried in a sand and cement screed. It is normal to control the flow of hot water by using a motorised valve controlled by a room thermostat, the heat source feeds a manifold where numerous circuits can be tapped off, each having it's own controlling stat and motorised valve.

In all similar installations heat is never instant, it can take several hours to get the screed to a reasonable temperature to raise the room temp, unlike a wet radiator ststem which can be piping hot in around 20 minutes.


SillyOldDuffer06/02/2022 21:54:31
8895 forum posts
1998 photos

Keeping the room warm requires a certain amount of energy in the form of heat. Various ways of providing the same amount of heat:

  • A small very hot surface such as the bar on an electric fire, or
  • A larger surface at moderate temperature like a central heating radiator full of hot water, say 80°C

So a huge surface, like an underfloor heater, can be operated at a lower temperature and work as well as other systems.   Surface area and temperature are inter-related.

All of them rely on insulation to make sure energy isn't wasted.



Edited By SillyOldDuffer on 06/02/2022 21:56:52

Nick Welburn06/02/2022 21:59:45
134 forum posts

Yep, our kitchen space, 110sqm or so of slate flooring has about 30-35 degrees on the manifold.
upstairs is more like 45-50 as the carpet and timber is less conductive

Ian P06/02/2022 22:16:31
2594 forum posts
114 photos
I stumbled across this youtube video which does explain quite a bit about home heating
Ian P

Edited By Ian P on 06/02/2022 22:17:51

Apologies for not creating a sensibly usable link


Edited By Ian P on 06/02/2022 22:19:05

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