On 22/01/2018 18:53, Mr Pounder Esquire wrote:
John Rumm wrote:
On 22/01/2018 17:21, Mr Pounder Esquire wrote:
A few weeks ago British Gas serviced the boiler. Not my idea. Nice
young lady who left me a leak on the Magfilter.
Since the service we have noticed that the house takes a LOT longer
to warm up. Before the service the place was warm in a couple of
hours. After the service the house took about five hours to get warm
- with the boiler running of course. The rads were hot, but not as
hot as before the service. I suspected that she had turned the
temperature on the heating side of the boiler down, but was to lazy
to check as the boiler is in the loft. Today I had a look. From 3/4 she
had turned the temp down to 1/2.
She did not tell me that she had done this. The temp setting had
been on 3/4 since the boiler was installed eight years ago.
I turned back up to 3/4 and the house was warm in no time, rads very
hot. Would I be correct in thinking that two hours running on 3/4 uses
less gas than five hours running on 1/2?

Do your turn the heating off after two hours normally?

Yes. It's the way we like to do it. Then maybe back on for an hour, this
several hours later. The house is very well insulated.

In reality it depends on several factors... If its a condenser, then
they gain in efficiency as the return temperature falls. So just warm
enough to do the job will typically get best results. Most boilers
these days can adjust their output power to suit the load
(modulation), but raising the flow temp can also raise the minimum
heat input to the system - so on milder days may promote more cycling
of the boiler. That will also reduce efficiency a bit. (although on
modern boilers its less of a problem than on old systems without pump
run on).
The ideal situation is the boiler just ticking over supplying heat at
the same rate the property is losing it - that will give good comfort
and efficiency. However the problem with that approach is on cold days
it will struggle to get the place work quickly. (tis why posh systems
use weather compensation)

Five hours to reach 22C?

Without knowing the flow temperature at the two settings it's not
possible to tell.

Why not have a room stat to set the desired temperature, and then leave
the boiler at 1/2 or even less?