Boiler status C even when no heating called for

[CBW]

Trace the cables. If they go down look that way if they go up, go upstairs and look in a cupboard, probably near where the other thermostat is located. I think you're misunderstanding what @terryplumb is asking you. When the boiler is showing a C when it's not supposed to, do a set of radiators heat up too? If yes, which ones?

 

[CBW]

What is this cable for?

 

[bizzle1236]

When the boiler is showing a C when it's not supposed to, do a set of radiators heat up too? If yes, which ones?

Ah I see I understand the question now. No radiators heat up. They’re cold as I would expect/ hope. They only warm up when the thermostat clicks on either automatically or manually.

About that cable. It comes from the boiler isolation switch. And two grey cables come out the top and go into the ceiling. There is no way to access where those cables go…. It’s a small hole they both disappear into, I’ve attached a pic.

 

[bizzle1236]

Can’t see any valves at all, none here either. not sure now where else to look! Either way I think to change a valve which is stuck or motor broken will need a plumber I assume

 

[CBW]

It might just need tracing. Fault is going to lie with either a failed valve or thermostat. Probably best getting a plumber/heating engineer in.

 

[bizzle1236]

It might just need tracing. Fault is going to lie with either a failed valve or thermostat. Probably best getting a plumber/heating engineer in.

I took the batteries out of the thermostats and the boiler stays stuck on C so I assume failed valve where it is. I’ll get an engineer

Many thanks for both your help

 

[CBW]

I took the batteries out of the thermostats and the boiler stays stuck on C so I assume failed valve where it is. I’ll get an engineer

Many thanks for both your help

Battery removal wouldn't necessarily prove that, but yes get an engineer

 

[bizzle1236]

Battery removal wouldn't necessarily prove that, but yes get an engineer

Thanks.

And because the manual is not clear;

If no demand for central heating from the thermostat when water and heating mode is selected on the dial, should I expect status 0 when the boiler is idling in this way? Instead of the permanent status c?

 

[terryplumb]

Yes,the O represents stand by mode.. boiler waiting for a demand for hot water or heating.