I have a closed heating system with 6 motorised valves to zone the rooms/areas plus a heat leak (two 1” vertical pipes are joined by 15mm pipes). I noticed recently boiler continually firing up for a minute or so even though all zones had reached temperature and to double check I turned all zones off and it still happened. So sounds like the boiler is just heating the water in the heat leak - is this a fault with the pump ie. it’s not switching off therefore as soon as the heat leak water cools it fires the boiler?
Thanks for any advice
Thanks for any advice