funduffer wrote:I have used at least 20% less gas every month this year compared to 2021. I have been struggling to understand why.
Yes, I have added some insulation, but this was in May, after the winter, so it can't be that.
Has it been a warmer than usual winter, well maybe. My thermostat settings have not changed.
I have a condensing combi boiler, and following some advice from my energy supplier (Octopus), in December 2021 I reset my boiler output temperatures to 55C for the radiators, and 50C for hot water. I can only assume this means the boiler is working much more efficiently at these temperatures than what I had previously. If so, that is astonishing.
In case anyone says this means the house is colder, I don't think so. The central heating is on longer, but the rooms still reach their target temperature.
FD
I'm not sure about the hot water side, but reducing the boiler temperature on the central heating side can make quite a difference.
The key is not the temperature of the water leaving the boiler, but the temperature of the cooler water returning to the boiler after completing it's circuit through the radiators.
If the returning water is above 54C or thereabouts, condensing will not occur, and it is this which makes a condensing boiler more efficient. If you have the central heating flow temperature set at 70C or so, there is a good chance that the return flow will be too hot to condense and therefore more gas will be used.
By having the flow set to 55C you can guarantee that the return will always be in the condensing range. I do this and prefer the lower radiator temperature. It may just be psychological but it seems to produce a more even temperature because it seems to reduce cycle of heating, subsequent overshoot before the thermostat reacts and the radiators cool, followed by the subsequent cooling, which then keeps repeating. Two possible downsides; first it obviously takes longer to heat up in the morning, so I have to set it to come on a bit earlier, and second, though I've yet to experience it, the setting might not be sufficient to keep the room at the required temperature if it's exceptionally cold outside.