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£5/day? that could be a pack of 3 socks every day. no brainer.
 
https://www.screwflix..com/p/dickies-cushion-crew-socks-black-size-7-11-5-pack/49250
 
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 ?
 
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.
 
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.
 
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.
 
... for design purposes, you can consider the oversite concrete to be a constant 5 degrees.
Which is (I assume) a true statement, but does not actually support your blanket statement. "For design purposes" really means "if you want to avoid calculating actual figures, then this will be near enough for common situations". U (or R) values for soil varies significantly, but it DOES have thermal resistance, and it is not "negligible".
And as I said, part of the reason it will appear to have exceedingly poor insulating qualities is the thermal mass that will suck heat away until equilibrium is reached. Put another way, if you did rely on a couple of meters of soil as insulation - you'd find yourself putting lots of heat in initially and might conclude that the soil has no insulating quality, but that heat isn't "gone", that thermal mass is now holding much of it.
And "I've designed and installed ..." is not automatically a qualification to be taken at face value*. If you've always assumed that soil is not an insulator, and you've always assumed that the oversite is a constant 5˚C, then you have probably never even considered the design of an earth insulated system. And if you've never looked at the numbers, then your experience is not relevant to the specific case in point.
Not that I plan on relying on soil for thermal insulation - it won't be necessary.

* Apologies, this really isn't aimed at yourself, but I've met a few "heating engineers" who I wouldn't trust to plug in a fan heater. And often the reason for "disagreement" is them relying on stuff they take for granted - like "it's illegal for a homeowner to touch anything to do with gas" (it isn't) and "the boiler must be connected with a fused spur, it's in the instructions" (I made them put the socket back when doing mum's boiler, and it wasn't). And my favourite was the guy who was 101% adamant that Grundfoss, DAB, Wilo (and I assume others) don't make these modern modulating pumps.
 
In China, we recommend Dry UFH system(water pipe), save one third of the gas cost compared with the traditional wet method, also fast heat up, while the initial installation cost is slightly higher.
We also provide electric system, however the result is low market acceptance in China, for example Shanghai, due to the cost.
 
In China, we recommend Dry UFH system(water pipe), save one third of the gas cost compared with the traditional wet method, also fast heat up, while the initial installation cost is slightly higher.
"Dry UFH system(water pipe)" - so that's pipes carrying hot water embedded in (e.g.) a concrete slab ? We call that a wet UFH system because the heat carrying medium is water. If you say dry, then to most of us (or at least to me) that implies no water, so probably electric.
We also provide electric system, however the result is low market acceptance in China, for example Shanghai, due to the cost.
Ah, so same problem as here then - lecky costs a lot more per unit of energy than gas does.
A resident of a residential area with pre installed floor heating by a developer found us and installed floor heating, and then compared it with other residents in the same residential area.
I don't quite follow that. I read it as the property was built with UFH by the developer - but the resident came to you to install UFH ? Or was it electric originally installed, and you replaced it with a wet (water) system ? Or something else ?
 
"Dry UFH system(water pipe)" - so that's pipes carrying hot water embedded in (e.g.) a concrete slab ? We call that a wet UFH system because the heat carrying medium is water. If you say dry, then to most of us (or at least to me) that implies no water, so probably electric.

Ah, so same problem as here then - lecky costs a lot more per unit of energy than gas does.

I don't quite follow that. I read it as the property was built with UFH by the developer - but the resident came to you to install UFH ? Or was it electric originally installed, and you replaced it with a wet (water) system ? Or something else ?
Dear Simon,
Hello! Nice to meet you!
First of all, in China, we identify the heating system as WET or DRY by whether there is cement backfill in the end of UFH process.
I will list some common construction systems in China's floor heating market as below ——
XPS foam board + manual clips + water pipe + cement + tile = WET
EPS foam slotted board + aluminum layer + water pipe + wood floor = DRY
EPS foam slotted board + aluminum layer + water pipe + cement + tile = WET
XPS foam board + aluminum layer + electric cable + wood floor = DRY
These are basically the above types.
Of course, the product types are not involved, e.g. XPS itself has many specifications to adapt to different needs.
In addition, as a result of home renovation, the resident chose our DRY system products.
Meanwhile, we need to conduct actual research on the product, we reached a cooperation with him and collected the gas cost.
Hope you can understand, and thank you for asking questions, cuz most people don't know about China's floor heating market.
 
In the UK, all of Europe and the USA any underfloor heating that contains water pipes is called WET, any electric UFH is called DRY, the type of construction is not taken into account. China's floor heating market is only of academic interest to most on here.
 
In the UK, all of Europe and the USA any underfloor heating that contains water pipes is called WET, any electric UFH is called DRY, the type of construction is not taken into account. China's floor heating market is only of academic interest to most on here.
Good afternoon, Mike,
The development of China's floor heating market is relatively slow, and industry standard documents related to floor heating were established in 2004.
Some technical terms are different from those in Europe.
Fortunately, we can understand each other.
Thank you for your correction.😆
 
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Ah, so same problem as here then - lecky costs a lot more per unit of energy than gas does.
Very much so, and why water UFH makes more sense as it can be fed from a heat pump.

Not up to date on prices, but until recently electricity was about 4 times the price of gas per unit energy, so even with a heat pump with a COP of around 3 (i.e. 3kW heat out for 1kW electricity in) gas is/was still a bit cheaper. However in the long-term that is going to change and so UFH is likely to work out cheaper.

Also a warm floor is really comfortable in winter!
 

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