Gas boiler settings

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? I never thought to take a meter reading.
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On Monday, 22 January 2018 17:21:39 UTC, Mr Pounder Esquire wrote:

Not necessarily; if it's a condensing boiler running on 1/2 may be more efficient.
Owain
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On 22/01/2018 17:21, Mr Pounder Esquire wrote:

Do your turn the heating off after two hours normally?
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)
--
Cheers,

John.
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John Rumm wrote:

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.

Five hours to reach 22C?

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On 22/01/2018 18:53, Mr Pounder Esquire wrote:

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?
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Fredxx wrote:

I have no means of measuring the flow temp. Condensing boiler. We like to sleep in a cool bedroom, say 18C or cooler. The way she set the boiler took 5 hours to warm the house by 4 degrees. Setting to 18C at bed time would still take 5 hours to reach 22C.
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