In article , David Hill david@abacusn
urseries.freeserve.co.uk writes
"....... Last night was very warm for December .. 10°C+ and set to "frost
protection" the heater still managed to switch itself on for a total of
nearly an hour ! Over a quarter this would mount up to quite a few ££ on my
electricity bill. I wonder how many people use these heaters without
realizing what it's costing them in wasted power ..........."

and if you were using paraffin or gas then the heater would be on all the
time and would cost a lot more than the electric as it would be on for
around 12 hours a night.
If you find an hour a night excessive then forget about heating, there will
be times when you could have it going for around 20 hours out of 24, and for
a couple of weeks.
You have to decide if the things you want to keep are really worth it.

And I presume you have adequate insulation? Our greenhouse is double
glazed, and I add a layer of bubble wrap in winter.
--
Kay Easton

Edward's earthworm page:
http://www.scarboro.demon.co.uk/edward/index.htm