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.


There is tho.

In order to warm up the house fully - structure and all - you have to
actually make it hotter inside for a time. This *partially* offsets the
benefits of timed running.

With UF heating, I have found it simpler to run it 24 hours for the last
month. A complex predictive timeclock and stat is probably better, but I
haven't yet installed one.

The fuel burn rate seems very little different from running it timed.



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.



Thsi takes no account of thermal interia. If teh time constant of the
building is anywhere over a few hours, it will stay warm and decay
agfter heating is off - a net gain for you, but rewquire a huge burn
first thing on switch on to restore. And take several hours to get fully
warm. By understanding this you can adjust your timeclock accprdingly,
but the option of switching off, and immmediately ceasing to lose heat
as the inside temperature plummets to zero when you leave for work,
followed by instant restoration to 22C or whatever the moment the boilre
fires up is not possible in practice.

The better the insulation and the more thermal mass there is the less
there is to gain from timed usage.