Boiler thermostat query

[Tia4]

Good morning everyone! A frosty one here in the NE England! My central heating boiler in the kitchen has a switch on the thermostat giving a high or low option. Does this only control the water temperature in taps and radiators? I think we should set it to high but my husband always leaves it on low - is there a possible money saving solution in either option do you think?
Thanks, Tia

you don't say what sort of boiler it is.

A modern condensing boiler runs most efficiently at about 60C, which is (probably) the low temperature. It will also turn the flame size up and down ("modulate") to provide the amount of heat required in the most economical way. If it is a combi boiler it is probably sized to provide the hot water, which is generally much more power than is needed to heat the house.

If the low setting does not provide enough heat for the house in exceptionally cold weather, you may have to turn it up to high. It does not matter if the boiler is burning continually at the low setting, this is more economical than switching on and off frequently. The radiators will also provide a more gentle and even heat.

If you have lost the instruction book for your boiler, you can probably download it from the makers website.

Thank you so much - it's an inherited combi boiler (Myson Apollo) and we don't have the manual but I will look online!

Tia.