Stuck 2 port valve versus boiler high limit stat....

[Bunker]

At a job replacing a cylinder and he mentions the boiler kept running even though the programmer wasnt calling. Apparently some history of the CH 2PV sticking on. I found it under some floorboards....nice. So even with the actuator closed, the switch is ON and therefore running the boiler (there is a bypass fortunately). But this triggered the high limit stat on the Dual Stat.
So, job 1 is to replace the 2pv relocating if possible. If the high limit stat has popped, does that mean the control stat is cattle trucked?
Thank'ee

 

[Leo21]

Depends on the boiler. What boiler is it?

 

[SafeGasInstall]

very likely they fail at the same time , when they turn power of and pump stopped over running

 

[Bunker]

Depends on the boiler. What boiler is it?

Well its an old Warmflow (Oil) but its a regular Imit Dual stat.

very likely they fail at the same time , when they turn power of and pump stopped over running

Well I wondered that but if the control stat is set to 70, doesnt the high limit stat pop at about 95? so the control stat should have cut off..

 

[SafeGasInstall]

True but if there is no pump to push heat out ....

 

[Bunker]

True but if there is no pump to push heat out ....

Ahhh, yes I like it, so pump goes off and primary water just sits there brewing and soaking up heat from the jacket etc. I didnt think about that. Good work thanks.

 

[SafeGasInstall]

Could be a faulty motorised valve not sending a swL back and cutting boiler out and no over run .
I have seen pumps that are almost gone doing similar thing as there was no auto bypass

 

[SafeGasInstall]

Basically pump is so weak as it has been pumping when there was swL but auto bypass is missing therefore pump becomes so weak and struggles to clear he and cousin a over heat

 

[Bunker]

Its a new Alpha but as per OP, 2PV has history of sticking on.

 

[lame plumber]

overheat stats just been doing its job as per the instructions on the tin

 

[Bunker]

overheat stats just been doing its job as per the instructions on the tin

Well done LP. Is that what you'd say to your custards? "Madam, that's another £65 call out for pressing your HT nipple, nowt to worry about, its just doing its job. Same time tomorrow?"....I guess the rest of us would be interested in the cause rather than the effect.