wrote in message
oups.com...

You shouldn't think that I have changed my tune on this, I was
involved in active and passive solar design of buildings in the
1980s.

I dont know if that was without any formal qualifications or with. I'm
also aware the general level of solar design has come a fair way since
then. Either way, I find your position hard to agree with, sometimes on
fairly basic principles..

To dismiss hyronic solar space heating systems out of hand is a bit silly.
OK, with a nice site and new design, a new superinsulated house designed
properly and built to passive solar principles can work.

If you have an existing house and renovating then matters become different.
Solar air heaters knock cobs off a wet system, but a conservatory is really
needed and heat is difficult to store. A south facing roof that is made
into one complete wet panel, using a large 2,000 litre plus thermal store
and very low temp UFH is feasible indeed, and in winter too as it can store
a couple days heat when cloudy.

The cost when doing a renovation is not that great, as probably the roof
needed doing anyway, you were installing UFH anyway, etc. So, the cost over
and above what you would have paid is the cost.

Don't dismiss hydronic systems.