How good is underfloor heating in a large room

[telectrix]

£5/day? that could be a pack of 3 socks every day. no brainer.

 

[nicebutdim]

Struggling to get my head around these costs for heating a single room.

Also struggling to find packs of 3 socks anywhere online.

 

[telectrix]

https://www.NoLinkingToThis/p/dickies-cushion-crew-socks-black-size-7-11-5-pack/49250

 

[nicebutdim]

That pack of 6 seems better value ?

 

[pc1966]

Think of poor Jake the Peg, he needed 3 socks.

 

[telectrix]

Think of poor Jake the Peg, he needed 3 socks.

and now he's got 10 years.

 

[Simon47]

It stays on all day in the winter keeping my feet lovely and warm. It also costs a bloody fortune!!!!! I wish I'd bought a pair of slippers!

Our kitchen has a solid concrete floor - I believe it's insulated. But no amount of insulation will make an unheated slab of concrete anything other than a cold slab of concrete. Even with two pairs of sock and slippers it's 'kin cold underfoot. Yes most new-builds I've looked over the wall at have all had unheated slabs of cold concrete to make sure the occupants always have cold feet ? And of course, with a solid concrete floor, it's the hardest to retrofit UFH to.
My plan is that eventually everything downstairs, and possibly much of upstairs, will have wet UFH. "Eventually". It's going to take some work to dig 2" off the slab but it's going to get done ... eventually.
One time a while ago when "going on about it" (according to SWMBO) she turned round and asked if I wanted under-coffin heating when I went ?

 

[Mike Johnson]

This all gets down to how your house is constructed, if its a Raft foundation you are stuck with possibly a screed on top of a concrete floor that can be taken up, but it will only be 50mm thick, taking that up and putting in 25mm of insulation will be better than nothing.

If you ground floor is built in the traditional way with footings and an independent floor slab, then taking that up and re-laying with insulation will be hard, but a worthwhile job.

If your ground floor is a beam and block construction you have all sorts of problems with end bearings of the beam and its possible intermediate supports if any, but what ever screed is on top of the beam and block can be hacked up and insulation and thin UFU put in.

There is 10mm wet UFH available, but the key is always the amount of insulation you can lay under it.

 

[Simon47]

My assumption is that the kitchen (modern extension) is a footings and separate slab - I'll cross the road of whether there's a separate screed on top when we get to that. As it happens, the guy that built it (DIY) now lives a few doors down the road, I need to catch him when he's free and pick his brains over a few details (like where the 2off 2.5 T&E leaving the CU changes into the SWA going out to the greenhouse, and whether the tee in the water supply pipe is buried under the kitchen floor slab ?) sometime - would sure beat having to find everything myself.
Part of the original ground floor is also solid concrete, and I suspect that's integral to the walls as a stability measure. After 80 years, I think that's going to be very well cured and solid.

But actually, apart from around the outside, insulation doesn't make much difference to energy requirements. In the middle of the room, you've got "lots of thickness" of earth underneath. So while it will take a lot longer to heat up, once heated up it won't take more energy. The only complication really is that around the outside walls, you have a cold bridge to the outside ground surface - especially if (as seems to be a requirement) they've filled the cavity up to DPC level with concrete to reduce the insulating properties of the building.
But if the cavity were left empty, and say it's 1/2m down to the footing slab, then you've 1m of earth between the floor slab and the outside ground surface.

My eventual plan is to have a radiator to provide rapid response, and UFH to provide comfort underfoot - the flow to the rad going via the UFH manifold first so the (smart) rad TRV will control both.

 

[brianmoooore]

But actually, apart from around the outside, insulation doesn't make much difference to energy requirements. In the middle of the room, you've got "lots of thickness" of earth underneath. So while it will take a lot longer to heat up, once heated up it won't take more energy.

Nice theory, but unfortunately it doesn't work like that. The mass of earth is very good at conducting heat away, and for design purposes, you can consider the oversite concrete to be a constant 5 degrees.
It's not something I tend to publicise on here too often, but my business had a plumbing and heating arm to it as well as electrics, and I've designed and installed several complete house wet UFH systems since they became popular.