Whats humungous, how big a home, what is insulation, any bill is big
when its time to pay it. But dont freeze yourself.

I have the following programmed into my thermostat:

Daytime 20
Evening (16:30 onwards) 22
Night 17

In reality it hardly ever comes on at night (if it does I normally wake as I
think it is time to get up!)

Need to reduce heat losses - take care not to open doors too much - or for
too long or all the heat disappears.


If you are used to a cold house and now have CH the bill will be much
bigger.

As others have said do a weekly meter read if you want to avoid nasty
surprises. My house which is insulated to standards of 20 years ago,
detached and a with heating off at night and set to about 20 during the
day with kids leaving doors open etc - yearly gas & electric bill about
£1000