Valliant Pump Overrun s.07

[Raje]

Hi hoping someone can help...

I have a valliant ecotech plus 637 installed in a refurbished property.

The boiler will not heat the radiators as it keeps cycling to code S.07 pump overrun as the temperature shown on the boiler display rises from 40degrees c to 80 in the space of a few minutes.

Radiators have been bled
Shield valves on rads open
Boiler isolation valves open (interestingly when these are closed the boiler continues running without overheating)

Next steps will be to call an engineer out but wondering if im missing something straightforward and any advice appreciated i can use to sort myself.

Thanks, Raj

 

[JohnD]

Boiler isolation valves open (interestingly when these are closed the boiler continues running without overheating)

sounds like you are misreading the isolation valves, and they are shut when you think they are open.

Post photos of them please

 

[ianmcd]

Agree with @JohnD , think you are mixing up the open and closed on the valves

 

[Raje]

JohnD

Thanks for your help - i turned the valves and left it on long enough and all radiators heated and hot water working.

Not sure how the hot water and some of the heating has been working until now!

I initially thought closed as outlet pipe was only getting hot in closed position.

 

[ianmcd]

Yes the valves are open now, for others reading this the line on the nut that turns on the valve indicates the flow position of the valve, if inline then the valve is open, if across then the valve is closed

 

[ScottishGasMan]

How many radiators are you heating with that boiler?

 

[ianmcd]

How many radiators are you heating with that boiler?

you are over thinking it lad , he had the iso valves closed