Worcester boiler pump runs for hours

[John.g]

If the CH is on and you turn the roomstat down, does the pump stop after its overrun period and then restart shortly later or does it just keep running continuously?
What does it do when you turn off DHW with eco mode selected on? and is the behaviour the same with Eco mode selected off (DHW preheat on)?.

What do Worcester say?

 

[George4321]

Hi. I have tried everything you mentioned. No, after about 20seconds from power up it starts its pump (just pump) and runs forever. If CH or HW used during this running that works normally but the pump continues afterwards and continues constantly and doesn't stop after normal overrun period.
As I said in my 1st post - the only way I have worked out to stop this is if there is a "demand" any demand, that could be heating, hot water or water heating if eco button is off, as soon as boiler turned on from the mains. So long as the fan & burner run immediatly the boiler is turned on once that initial demand is stopped the pump will stop just as it should after its 3 min overrun period. But without that instant demant on power up the pump will start after about 30seconds and never ever stop. So unless by chance the room thermostat is turned up & the heating set on on when the power comes off the boiler will do its constant pump running, that means any powercut in summer for sure will send it into its constant pump running.

 

[Michael H]

Hi. I have tried everything you mentioned. No, after about 20seconds from power up it starts its pump (just pump) and runs forever. If CH or HW used during this running that works normally but the pump continues afterwards and continues constantly and doesn't stop after normal overrun period.
As I said in my 1st post - the only way I have worked out to stop this is if there is a "demand" any demand, that could be heating, hot water or water heating if eco button is off, as soon as boiler turned on from the mains. So long as the fan & burner run immediatly the boiler is turned on once that initial demand is stopped the pump will stop just as it should after its 3 min overrun period. But without that instant demant on power up the pump will start after about 30seconds and never ever stop. So unless by chance the room thermostat is turned up & the heating set on on when the power comes off the boiler will do its constant pump running, that means any powercut in summer for sure will send it into its constant pump running.

I have exactly the same problem, it’s had a new pcb, pump, diverter motor and as far as I know all the sensor’s replaced, it’s also had the heat exchanger removed and cleaned and the pump still constantly runs, occasionally if I press the reset button it will stop, start for few minutes before finally stopping only to start running again a short time later, one thing that is slightly different is that the water temperature drops from 55 degrees to between 17 and 20 by about 1 degree per second

 

[Knappers]

Worcester help page says check purple/black wire to pump

 

[John.g]

The outside temperature compensation because of its stupid requirement to keep the pump runnimg 24/7 may still be influincing this even if not connected/installed, is there any parameter/switch to select temperature comp. On/Off.?

 

[George4321]

No afraid not. I have contacted worchester bosch as well, this boiler does not have a weather/temperature compensation unless an external unit is connected (which it isn't). There is no setting to turn it on/off and is only active if fitted.

 

[John.g]

What's left then? frost protection problem, PCB?, you would think worchester should be able to track down whatever is telling the circ pump to run like this expecially since your's isn't the only one.

 

[George4321]

Thats the confusion! My gas enginner who serviced it last week put a new PCB on it and was rather lost by the problem. "the pump can only run if the PCB tells it to" was how it was left but the PCB is new. No fault codes or anything. WB are also lost and can only suggest get engineer to phone them when the boiler is opened up to test each component - maybe I will do that next year at its service. It would make sense being frost protection but if it was a sensor or something then I don't get why it only does this if unit is turned on from the mains without a "demand" but if there is a "demand" at time of turning on its all ok and functions normally and its pump turnes off as expected, i would expect the fault all the time. Looks something i will just have to live with, thanks for your help.

 

[ShaunCorbs]

Why is the mains being turned off and on ? Boiler should have constant power

 

[George4321]

Only turns off in a powercut which for some reason we have a few times a month, often just a few seconds but enough to cause issues with the boiler. Turning it off for longer makes no difference, any loss of power for any length of time causes this pump to run 24/7. Concerned could occur when away meaning pump would run for days and days.