Velvet wrote:

Alan Shilling wrote:

"Velvet" wrote in message
...

Snipped

That's how I got to wondering which one actually does use more gas, and
therefore, costs more... and searched the web, but to no avail, no
concrete examples and theories that demonstrate the differences between
the two methods seem to exist. And whilst I'd give it a go as a home
experiment, I know the weather's too variable to make the results
worthwhile.

Oh well. Ta for the replies. Anyone else?



Hi it's me again, maybe I didn't provide a simple enough explanation - if
you run continuously you'll use more gas. This is because the average
temperature inside the house will be higher and hence the heat loss to
the
outside will be greater (as I'm sure someone else has also pointed out).

You're probably thinking that there is some complex stuff going on here -
but there isn't. Think of your house as a box with gas going into it and
heat coming out. The hotter it is inside, the more heat comes out and the
more gas has to go in. You can reduce the gas going in by lowering the
temperature (overall or for a few hours at a time) or by improving the
insulation.



Ok, but what about once the house (fabric of) has cooled. Surely you
end up pumping more energy/heat into it, some of which leaks out, some
of which is absorbed by the house fabric, and only then do you start
actually raising the temperature of the air within (once the house has
stopped sucking heat out of the air).

That's the crux of the question for me. The longer the heating is off,
the further it cools, and the more energy you need to put in to raise
the temperature again. It's the comparison between energy used to raise
it back to temp and energy used to maintain a temp that I wanted to find
out about.


In theory iots always less to time, because the energy you put in to
warm it up, keeps it warm after you have switched off teh heating. This
of course is a net waste and leads you to advance the timing so teh
house is warm when you get in and when you leave. In teh case of high
enough thermal inertia:heat loss ratio this results in the system being
on nearly 24 hours anyway.

So you might as well leave it on.




Velvet