Most efficient boiler settings

[Deleted User]

All the clarification that is needed:

https://octopus.energy/blog/winter-workout-gas-saving-tips/

aoleks

in my case it's simple: the boiler is set up to heat the radiator water to 70 degrees and the taps to 50 degrees (combi boiler, newest generation). there is a thermostat in the kitchen/diner, where we spend most time, set to 21 degrees during the day and 20 degrees during the night (usually colder during the night, but with a baby that wakes up multiple times a night, my other half won't accept anything below 20 as she's the one who goes to him nearly naked).

radiators are all on max, with TRV valves and the house is really well insulated. in essence, the boiler switches on every now and then to keep the temperature at 21, but it rarely goes below that, even when it's really cold outside.

when the temperatures go up a bit (let's say above 10 degrees during the day and not less than 5 at time), we override these settings by switching everything off during the day and only switching it on for half an hour to heat things up when it gets a bit cold. not more than 2-3 times a day, though.

Norman_Castle

aoleks said:

radiators are all on max, with TRV valves

Why? Maximum is about 90 degrees, put them halfway which is 70 degrees and adjust up or down in small amounts over time.

Its pointless having TRVs if they're set to maximum.    

coffeehound

Norman_Castle said:

aoleks said:

radiators are all on max, with TRV valves

Why? Maximum is about 90 degrees, put them halfway which is 70 degrees and adjust up or down in small amounts over time.

Its pointless having TRVs if they're set to maximum.    

I think that advice goes back to the original suggestions by the Telegraph guy.  The idea is that by having all rads always on, you are helping to ensure the return flow is cooler.  I don't know if it makes sense.  I tend to keep them set on something sensible like 22 so that if a room gets more solar gain, the rad is turned off.

BUFF

Dolor said:

All the clarification that is needed:

https://octopus.energy/blog/winter-workout-gas-saving-tips/

tbh I think that they have got their suggested temps the wrong way around for a combi - at least for an older property.
I would suggest that for many 55C flow & 50C hot water makes more sense rather than the other way around (& I say that running 53C flow in an older property).
& of course, as mentioned throughout this thread, there are many variables - no 1 solution for all.

coffeehound

The suggestion to set flow to 'a few degrees above 60' to heat a tank to 60 is bad advice; it'll take forever to satisfy the thermostat, just grinding away in non-condensing reduced-efficiency mode

blagoslovljena

Thanks for the info guys. 😊

Brief update. Woke up this morning to kids’ room thermometers showing 24C and 23C, even after turning the boiler CH setting down from 4 to 3, which has confused me a bit! Admittedly it was a warmer night and we leave the heating on overnight, but they were pretty toasty in the evening so I had turned the TRVs down a little before they went to bed.

This morning I turned the boiler CH down to 2.5 to try and lower the temp in the bedrooms and left the TRVs on the lower overnight setting, and it’s currently 24C in both so I’ve no idea what’s going on! 🤣 Downstairs is normal temp for us ie prob around 21-22C.

Boiler isn’t constantly firing, and when it does fire up I’m seeing steam coming out of the flue outside so I’m assuming it’s condensing ok. But it seems odd that it’s practically bikini weather in the bedrooms after turning the boiler CH setting down and having the TRVs in there almost on  ❄️. Definitely warmer than it was when the CH was set to 4 on the boiler. 🤔

Have I broken my CH system? 😳

Norman_Castle

blagoslovljena said:

Boiler isn’t constantly firing, and when it does fire up I’m seeing steam coming out of the flue outside so I’m assuming it’s condensing ok.

Steam from the flue means its not condensing.

BUFF

Norman_Castle said:

blagoslovljena said:

Boiler isn’t constantly firing, and when it does fire up I’m seeing steam coming out of the flue outside so I’m assuming it’s condensing ok.

Steam from the flue means its not condensing.

Not condensing *fully* - but imo you wouldn't expect to get 100% condensing at the flue (when the return temp is probably ~30C over ambient) without further flue recovery etc.
On the other hand, if your flue gases are way, way above ambient temp you won't see vapour directly at the flue as they won't cool down to dewpoint until they are away from it.

Bendy_House

blagoslovljena said:

Thanks for the info guys. 😊

Brief update. Woke up this morning to kids’ room thermometers showing 24C and 23C, even after turning the boiler CH setting down from 4 to 3, which has confused me a bit! Admittedly it was a warmer night and we leave the heating on overnight, but they were pretty toasty in the evening so I had turned the TRVs down a little before they went to bed.

This morning I turned the boiler CH down to 2.5 to try and lower the temp in the bedrooms and left the TRVs on the lower overnight setting, and it’s currently 24C in both so I’ve no idea what’s going on! 🤣 Downstairs is normal temp for us ie prob around 21-22C.

Boiler isn’t constantly firing, and when it does fire up I’m seeing steam coming out of the flue outside so I’m assuming it’s condensing ok. But it seems odd that it’s practically bikini weather in the bedrooms after turning the boiler CH setting down and having the TRVs in there almost on  ❄️. Definitely warmer than it was when the CH was set to 4 on the boiler. 🤔

Have I broken my CH system? 😳

No, not broken! Almost certainly just down to the milder weather recently. That's why modern boilers can benefit from a device called a 'weather compensator' which is an outside temp sensor which will automatically turn the boiler's flow temp up and down to suit.
So why are your bedrooms so warm? I don't know, but it's likely either that your bedroom TRVs are faulty (quite likely) or your bedrooms are upstairs and are getting heat from the rest of the house (unlikely to be that much).
If you turn a bedroom TRV down to 1 or below, the rad in a mild room should go 'cold'. Does it?