On Fri, 19 Dec 2008 12:26:00 -0800 (PST), wrote:

But switching the heating off overnight doesnt see a house lose much
temperature. To get the effect you mention it would need to be off a
month or more.

Depends a bit on the house and its construction. Our heating is off over
night from 2300 to about 0600. The start time varies as we have a
programmable stat with start optimsation. Temp might get down to 15C on a
windy night with temps outside down to -5C.

What we don't do is turn the heating off if we go away for a few days,
there is this uninsulated 18" thick solid stone wall right through the
middle of the building, this holds a lot of heat and if we let it get cool
it takes days, literally, before the place is comfortable again. The air
will be warm but 32 tonnes (guess 8 x 8 x .5m) of stone has one helluva
thermal mass. Advantge is that it keeps the place cool in summer and warm
in winter.

--
Cheers
Dave.