Well, I'm sorry about that!
I've had a look in English but the existence of this way of heating doesn't seem to be even acknowledged outside Krautland.
They somehow always seem to be one step ahead, we are just beginning to play with PV, when they've already lost interest in it and have moved on to experiment with ice!
What happened with the old British ingenuity?
Regards
germ
It looks like they are using that as a thermal store to ren the heatpump, using a crude solar thermal "grid" to add heat to the store, in addition to that, look at the earth that they have there, it would conduct heat quite well, unlike the "brash" we have around here.
These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then CLICK HERE and post a thread with who you are, and we'll send you some stats etc