Looking at a house with areo thermie heating can anyone explain the good and bad problems with this systemThanks john
That's an interesting proposition - I have been thinking about installing something similar, mainly for spring and autumn use, when we might not want to light the logburner, but need some background heat to take the chill off.
I assume you are talking about an air to air heat pump system - basically an air conditioning system which can operate in reverse mode to provide warm air rather than cooled air. They run entirely on electricity, but with a COP (coefficient of performance) of about 3.5 - 4 to one you get 3.5 to 4 kW of heat for every kW of electricity consumed, so they are much more economical to run than an electric radiator or convector. Typically, such a system will have an external unit with pipes to the inside connected to one or two (can be more) internal units, depending on size of space to be heated.
Not so sure the system would cope with real winter conditions, unless the house is modern with very good insulation. Air to air systems are much cheaper to install than geothermal wet systems, which usually have pipes buried in the garden, as well as underfloor pipes in the house. Geothermal is best installed when a new house is built, but air to air systems are mostly chosen for retro fitting, as they are much easier, albeit not quite as effective in use as underfloor systems.
The only downside to consider is the noise generated by the internal units. I have no experience to draw from - hopefully someone will reply to give their view on this. Of course, you could speak to the current owner to ask about the system, though given some of the technicalities involved, this can be difficult in French (for me, anyway). Good luck.
Split unit Air source heat pumps the type as described above are extremely efficient down to as low as minus 15deg, even lower depending on the unit, the internal units are virtually silent, we are presently having new heating system fitted using air source heat pumps to generate heat converting into conventional wet radiators downstairs and split unit fans up.
Used this system with work in some pretty extreme conditions its amazing the heat they generate even from below freezing very economical to run with a very low carbon footprint, simple to install in new or old builds overall installation costs is only slightly higher than comparable systems run on oil though running costs will be less than half, also if its a air blown system like our upper floor then you have the advantage to switch to cool air (AC) in warmer months
We installed underfloor heating with water served by an external aerothermie unit. There was therefore no internal unit and no noise considerations. The external unit emitted a soft whirr but nothing distracting
We had a small, inexpensive 7kw unit which adequately served the underfloor of our 45 m2 downstairs main room and boosted the temperatures upstairs as well. We let it run year round though of course with thermo set low in summer it would only kick in on a cold night.
There is a lot of negativity about these units but I would recommend them to anyone. I fitted our system myself with technical help from a much better qualified friend. The system has the added benefit of totally drying out the entire structure and aiding the health of the house as well as our lungs.
When we sold the property last September it was still going strong after some five or six years with minimal or zero servicing.
Thanks for your advice I was wondering if this system is suitable for a maison secondaire when the power will be switched off for long periods
As a refrigeration engineer I have no problem reccomending air source units but there are a couple of considerations. Firstly the efficiency of units quoted by manufacturers are a bit like the mileage per gallon figures quoted by car manufacturers and are based on optimum conditions - take into consideration compromises that have to be made on real installs and you will be very lucky to achieve those figures in actual practice..We measure the efficiency of an install by plotting a mathematical enthalpy graph so it is something that can be measured but I would not buy a sytstem based on the efficiency figures alone,. My main consideration would be the referigerant type in existing installs. because some have been phased out, some are being phased out and some are being phased down there is a consideration to be had. If you are looking at an old system with something like R22 then it is pretty useless and although it can be retrofitted with another gas it is cheaper to replace the whole system and there is a significant cost in removing the old because of disposal. With something like R404a and R410a then R404a is the next refrigerant to be phased out and R410 a will be phased down and in the meantime as demand exceeds supply they have become very expensive. If you are looking at a new installation therefore at the moment a good choice would be a unit with R32 refrigerant and if I personally were looking at purchasing a property with an existsing system I would completely disregard the existing system in any calculation of worth. Hope that makes sense.