the diverter valve does stick occasionally but is moving freely from Hw to heating, could that still be the problem, it was replaced a couple of years ago?
Can anyone help…my Worcester heatslave oil boiler does not fire up when calling for hw and the hw thermostat is unresponsive, when I had the heating on last nite I noticed the rads were pinging hot even though the heating thermostat is not set to full power, it has been locking out a few times...