Potterton Suprima 100L running 24/7

[Matt Hulks]

We have a 20 year old Potterton Suprima 100L system boiler. It’s running 24/7 and only way we can turn off CH is at boiler mains! Engineer replaced PCB and believes it will be the frost stat kicking in but it just doesn’t seem right (this hasnt happened before). As I say, even in milder temps today it’s running 24/7 despite no demand for CH or HW.

Any ideas welcome!

 

[Deleted member 120897]

Sounds like a failed motorised valve.