Boiler.

[Digit]

Here we go again!
Our boiler is 'cycling', with the room stat calling for heat the boiler fires up and runs as normal. Once it has reached the desired room temp the boiler shuts down.
All well and good thus far, later on, when the room stat calls for heat the boiler fires up and runs for some minutes then shuts down, showing a fault code. The book states 'temporary fault, wait!'
A check on the flow and return pipes shows little difference in temp between, thus I assume that the boiler's over temp stat has operated.
By-pass problem, pump, what have you?
Help.

Roy.

 

[OLD]

Some boilers have a pump run on to prevent 'heat soak' on a fully pumped system to keep the over temp stat. from operating, a special by pass valve takes the flow. Run on has to be wired in with the boiler controls.

 

[Digit]

The pump does run on OLD, and when the water temp drops the boiler fires up again, but the room stat is still calling for heat when the boiler stops heating.

Roy.

 

[Alex]

What type of boiler? If it's combi check condensing drain's not frozen/blocked.

 

[Digit]

It is, I will. Ta!

Roy.