chris French wrote:
There seems to be floating about among some people I know online the
idea that keeping the central heating on all the time is cheaper than
turning it off at night. Not sure where it comes from, but seeing as
they all frequent the same/ related e-mail lists, maybe from there.

The basic idea seems to be that it costs more to heat the house back up
in the morning, than to keep it at the same temp.

now I know it depends on things like internal and external temp (we have
a programmable stat set at 12-13 C, it hardly seems to turn on except
when down to about freezing outside from what I can tell),

But in principle it seems rubbish, it must use more energy to keep
something hot, than to let it cool and then reheat., but a couple of
people had been hard to convince, esp. as a 'plumber told me it)

Or is my brain addled?? :-)

The devil is in the detail, and whether your boiler is markedly more
efficient at a nice slow trickle of heat than a full bore blast to get a
cold house warm

I did a few calcs on this and by and large if your house has a fairly
large thermal mass, there isn't a lot on it either way, if its cardboard
and rockwool, then the balance tends to tip in favour of only heating it
when you need it, as the warm up time is pretty fast. BUT if yor biler
is markedly less efficient at flat out heating the balance even there
tips the other way,.

i finally gave up worrying about it.