Combi Boilers – a single usually wall unit that produces heating and hot water
As combi boilers produce both heating and hot water they show big outputs of 24kW and upwards. Many of us think this is for heating, but it is in fact for hot water and this is important to remember. The better the hot water performance, the bigger the boiler is for heating and this has implications for efficiency.
It is surprising to learn that the average UK home needs just 6-8kW for heating on a cold day, so most combi boilers are oversized for heating in order to get a better hot water performance. Your installer will also need to adjust the heating output of the boiler down to match the heat requirement of your property, e.g. 6-8kW.
For more help sizing your property try our Guide to boiler sizing and Why oversized boilers are bad for your bank balance and the planet.