I’ve been looking at this sort of thing recently. There are good, reasonably priced air source heat pumps designed to drive underfloor heating. We have a ground source heat pump with underfloor heating that is 11 years old and getting to the end of It’s life and will need replacing in the next few years. An air source heat pump to replace the existing ground source heat pump will be less than half the price. Yes, it won’t be quite as efficient as a ground source heat pump equivalent but then we don’t get cold winters here, two frosts in 5 years.
Have you thought about running costs. If you do 50 sq metres its a 5kW heater.
It would be similar with other sources of heating for that size of area. A wet system with a heat pump would reduce it to 1.8-2kw with the 10mm low profile system.
Thanks for taking time;) I will have separate reversible AC in all rooms, U/F el. heating Mats (100 w pr. sq. mtr. 3 mm thick ) glued to the stone tiles. in bath and bedroom (Concrete under glue).
The Living room (50 Sq. mtrs). has a closed fireplace (glassed in) so maybe that’s sufficient, , but I was thinking about U/F heating in 2 zones . Under the dining table area (10 sq. mtrs) . and in front of couch area (10 mtrs.). All zones with separate sensors( adjustable). The area is South France, and the idea is to give a little extra warmth during the coldest winter days only. Sound like a plan to you ?
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For anyone putting AC in a bedroom… I can vouch for Toshiba (no idea of the model number). In a hotel, for the first time, ever, I was able to sleep with the AC running… silently !!
Must be a very recent model… if anyone has any info I’d be interested for the future…
@Corona will know the proper words… all I can say is it was fitted on an inner wall of the bedroom, with ducting to a fan/box thing on the outside of the building…
Strangely, the bathroom had no AC but did have a small electric radiator (for winter), so not connected to the other stuff.
However, the cool of the bedroom would work its way into the small bathroom I reckon… as it seemed to be OK in there.
There was a large insulated hotwater tank in one of the bedroom cupboards and OH seem to think that was also connected to the outdoor thingy… (he did a lot of investigating once he’d cooled down 
)
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Well if I was in your shoes I’d do it. You only have one crack at it, it won’t cost a fortune and if you don’t do it you might always wonder (like I would 
) that might it not be that little bit nicer if you had. We only live once.
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Our house is 101 sq metres and the GSHP is about 2.1 Kw max input split into three zones. It is very well insulated though. It really does the job, and having a nice warm floor in the winter is wonderful.
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Good to get feedback from real world situations, thanks hairbear.
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I have a related unfinished project here in our Jura house.
When we moved in 20+ years ago, the floors downstairs (and some of those upstairs too) were pine tree trunks cut in half and laid cut side up. (Ceilings are similar but facing down, and with lime mortar laid over to seal and level them.) The ground floor trunks had rotted through, tho bedded in lime mortar. So we dug them out, laid a consolidated aggregate bed, then rigid insulation board, then concrete over, and finished again with ceramic tiles. This was to obtain the maximum useful thermal mass, since we are close to Mouthe, renowned for temperatures as low as -26 in winter.
We then insulated the walls internally to get the fastest possible heat build up, since we knew we would be coming in at the start of a holiday, and did not want to wait ages for the 60cm stone walls to warm. It still took about 3 days with the 12KW wood burner to get the temperatures stable, but we could get the house to 17 deg C or so from 2 deg C or so, in 3 hours from walking in. Before we did this, when we first bought the property, the pipes froze while we were away while it was unheated in winter. Since we did this, it never dropped below about 2 deg c internally in winter, despite external extremes and no heating in our long absences, just winter solar gain via the windows.
When we laid the concrete, we laid plastic plumbing circulation piping without any joints above the insulation, under the slabs, routed together at an accessible “sump” to be able to subsequently fit manifolds to connect each coil. I have yet to fit the manifolds. However the plan remains eventually to connect manifolds to a thermal hot water array outside via an insulated drain down tank. The “coolant” will be raised into the array using a pv panel powering a 12 volt pump., so there is only coolant in the array when the sun is shining on it. At the time I planned old radiators painted black behind glass, but now the new thermal arrays are so reasonably priced and efficient I would probably go with those.
As we are now living here, and occasionally experience summer heat build up after a number of days that makes it less comfortable inside, I have been considering also connecting to our below ground cistern, to run cooled “coolant” through at those times.
Very interesting, looking to do similar with solar thermal and a heat pump top up if required but also for the pool. I had to alter my plans for hempcrete walls on the storage area as it was thought out whilst in the UK but upon arrival there were some structural issues to address and also the addition weight loading of solar or PV panels meant building structural block walls.
Looking to get some quotes for V glass vs double glazed unit which will require machining of the doors and windows to allow the extra width of the glazing units.
Please keep posting as it great to hear how you are getting on, with your winter temps no wonder you want a drain back system.
I have just bought a ‘rugbuddy’ - sort of an electric blanket under your rug - for my living room. While it doesn’t warm the entire stone floor it certainly helps around the sofas and chairs. Loving having warm feet again. Too early to know exact costs of running but at 300kw it shouldn’t be excessive. I am very happy to recommend this and the supplier - https://www.bewarmer.co.uk/. They ship from the Netherlands!
Did you really mean 300Kw? Only that really would cost a lot and should definitely heat the entire house 
Oops - my iPad has a ‘sticky’ keypad. It all depends on the size of rug obviously so I just went onto the website and copied this. I only use mine in the evening.
- 50 x 100cm, (20 x 39 inches) 80Watts £134 (UK only) - (2.4p per hour)
- 50 x 150cm, (20 x 59 ins) 90Watts £149 - (2.7p per hour)
- 50 x 200cm, (20 x 79 ins) 120Watts £159 - (3.6p per hour)
- 100 x 150cm, (39 x 59 inches) 180Watts £184 - (5.4p per hour)
- 100 x 200cm, (39 x 79 inches) 250Watts £214 - (7.5p per hour)
- 125 x 160cm, (49 x 63 inches) 250Watts £214 - (7.5p per hour)
- 130 x 220cm, (51 x 87 inches) 350Watts £254 - (10.5p per hour)
- 150 x 230cm, (59 x 91 inches) 450Watts £289 - (13.5p per hour)
- 177 x 251cm, (70 x 99 inches) 600Watts £349 - (18.0p per hour)
Just as a footnote those running costs work out at a unit (kWh) price of 30p.
In France the running costs will be lower on all regulated electrical tarifs, apart from the 22 x 16 hour periods of Tempo Rouge…!