CH pump always on

[MikeAsp]

Hi Kit is Baxi Solo 350PF, Myson CP35 Pump, Drayton Motor Valve.

The pump keeps running when when both the water and heating are set off at the switch ie its still running at 3 in the morning. The only way to stop it is to turn off the mains power to the boiler. The pump is less than a year old and I think I had the MV replaced last year.

Any idea what the problem is

 

[bobbo85]

pump overun stat ,it should carry on when boiler shuts down,to allow excess heat to get away from boiler,but its just carrying on is it,and the boiler is cold when its happening.has it just started

 

[MikeAsp]

Yep started last night spotted it when I went to bed - a "whats that noise" moment

 

[MikeAsp]

pump overun stat ,it should carry on when boiler shuts down,to allow excess heat to get away from boiler,but its just carrying on is it,and the boiler is cold when its happening.has it just started

Is the overun stat part of the pump and can it be replaced or is it a new pump

 

[D_Hailsham]

According to the Mfrs Installation Instructions, the Baxi Solo 3 does not have an overrun thermostat. The pump overrun is done by a timer, which is presumably on the PCB as there is no mention of it in the Parts List.

It looks as if you might need a new PCB.

The problem will be nothing to do with the pump or the MV

 

[MikeAsp]

According to the Mfrs Installation Instructions, the Baxi Solo 3 does not have an overrun thermostat. The pump overrun is done by a timer, which is presumably on the PCB as there is no mention of it in the Parts List.

It looks as if you might need a new PCB.

The problem will be nothing to do with the pump or the MV

Thanks very much -- sounds like I need an electrician or is it a plumber or a specialist heating engineer

 

[D_Hailsham]

A heating engineer would do fine, just make sure he is familiar with the boiler. Just explain the symptoms, but do not tell him what you think is the cause; otherwise he may replace the PCB without properly checking

If you do not have a 'tame' boiler-man, ask friends/neighbours who they would recommend.