Pump runs continuously

[Duncan G]

I have a Myson powered Y type central heating sytem. It works ok but when the hot water only is selected, the Euramo pump runs continuously even when the boiler swiches off once the water has reached temperature. Is this normal or should the pump switch off at the same time as the boiler? 3 way valve and room thermo work fine.

Any ideas?

 

[Mbear]

It sounds fine to me, the 3port valve sends power to the pump&boiler at the same time, the boiler fires and the pump runs, the boiler however will only fire if the boiler stat is calling for heat, when the boiler stat is satisfied the boiler will stop firing even though the 3port is still sending power, the pump however doesn't have anything stop stop it working therefore will keep running until the 3port stops sending power(hw cyl stat satisfied).


Hope that's helpful

 

[Duncan G]

Thanks Mbear. Just turned the HW Cyl stat right down to 50 and it still didn't switch off. Maybe the stat is not working correctly?

 

[Mbear]

In that case the pump may be wired to a pump overrun switch in the boiler.

What kinda boiler is it?

 

[Duncan G]

A Myson Orion 60.

 

[Mbear]

A Myson Orion 60.

Remind me
Is the pump internal to this boiler? Ie inside the boiler as opposed to on the system

 

[Duncan G]

Not part of the boiler. It's a Euramo Gold.

 

[Mbear]

Not part of the boiler. It's a Euramo Gold.

Does it continue to run and never stop?

Or

Does it run for about 3mins then stop after the hw has been satisfied?

 

[Duncan G]

Doesn't stop.

 

[Mbear]

You'll need to get a heat eng in to trace where the voltage is coming from possibly, is there a purge/normal rocker switch on this boiler? Prob behind the front. I suppose the pump over run switch could be stuck 'on' on the pcb if it is indeed wired like that.

I'd need to have a look myself to be able to tell properly.

 

[Duncan G]

Where is this pump over run switch?