Worcester Greenstar Heatslave 25/32 - Pump Problems And Micro Switch

[kevmac]

My boiler is doing funny things, we switched on CH on for the winter last week, only the first 3 rads got hot, we thought the system was blocked, so dropped the pressure, and flushed the system, all ok, still only 5 rads getting hot, found that the pump was running all the time, pump became noisy, fitted new pump, all rads got hot ok, but pump still running, traced fault to micro switch in diverter head had melted and closed circuit power to pump, fitted new micro switch. all DHW and CH checks done so set system to auto. Then noticed that rads where boiling hot during day with CH off and diverter was set to position B, boiler keeps calling for heat when there is no demand.

[DIYorNot]

Disconnect the room thermostat and see if boiler remains off.