[quote]We have a "pompe à chaleur" which works like the back of a fridge in reverse. It does mean we have a huge great bank of pipes in the garden - about 12 ft long by 4 ft wide by 4ft high. They are gr...[/quote] please could you tell us how many square meters your pompe de chaleur is heating? was any of the paperwork associated with the cost of installation handed on to you and would that give and indication of how much installation cost? sorry, i know these questions are intrusive but it would be very helpful to have the information.