Combi-boiler-turn hot water tap on/off and the heating stops for circa 20seconds. Then restarts again.

Is this normal?

Thats what mine does.

All 3 I’ve used, including our new Worcester Bosch CDi, all do it. 🙂

Ah ok, I’m still mentally-shot from acquiring this house so any noise etc worries me greatly.

Yep – I think it is just trying to catch up with itself and try to ensure it doesn’t spurt out scalding hot water.

hot water takes priority over central heating so when you run the hot tap, heating is switched off. after you turn the hot water tap off the burners stay on to pre-heat water ready for the next draw off, sometimes referred to as the “keep hot facility”. after a few seconds the burners will extinguish or revert back to heating mode.

Yeah on my worcester combi there is a diverter valve – it feeds either the heating or the hot water. Don’t think it can do both at the same time..

Just moved into our new house and our new boiler won’t be installed until Thursday. Have spent a week huddled round an open fire and cooking on my camping stove.

Running out of clothes too, and starting to smell!

Kids don’t care though, my eldest looked a bit disappointed when told we’d all be able to wash by the weekend.