reverse cycle air conditioning heating is more efficient??

David, Do you ave a link on construction of your dolar heater. Have been looking at designs on web and want to build one. I would combine the passive heating with a reverse cycle aircon in evening..

cheers

George

David L. J> > > My Solar Air Heater gives me 500W heat output for a lousy 25W fan

Sure do:

Dave :)

Of course it's related, but NOT the same thing.

MrT.

Dave

Have you though about feeding the inlet from inside the roof space (near the apex) and using the heat generated by the tiles as well?

Alan

-- Sell your surplus electronic components at

Sure, but I prefer my air fresh!

You would need a very good filter for a start, and that impacts your airflow rate, possibly even negating any benefit gained from the pre-heated roof air. The filter would clog up very quickly too, roof spaces are horrible environments for dust.

Dave :)

OK on the dust, that's why I suggested near the apex. Perhaps a long metal tube passing through the roof space to the outside air? Just throwing an idea around.

There was a guy on the "New Inventors" who had a unit that took (filtered) air out of the roof space to feed down into the house for heating. Just thinking that you would increase the heat take up that way.

Alan

-- Sell your surplus electronic components at

I've visited a house that had the first prototype of a system like that installed, it didn't seem that impressive. I did some initial thermal mappings of my roof space to see if such a system was feasible, it just doesn't get that warm up there in winter. Perhaps it's my terracotta roof tiles...

Dave :)