Vaillant boiler, hot water is fine, no error codes but no heating

[grumpypj]

Hi

Property is a 2 bed flat with 5 radiators, boiler is Vaillant ecotec plus & there is a storage water tank.

Problem is suddenly this evening, radiators aren't heating up..what a day of the year for this to go wrong.

There is hot water without issues. Boiler shows no error codes. Pressure bar is healthily between maximum and minimum. Flame sign comes on every now and then. Radiator sign comes on too but sometimes it blinks and sometimes its solid. No unfamiliar noises are coming from boiler or radiator. Temperature on display reads 69 degrees C at this moment. Thermostat is set up at 26 degrees.

What I have tried?
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1. I have tried resetting boiler.
2. Bled all but 1 radiators. I can't reach the valve on the 5th one. While bleeding the 4 radiators, I didn't hear any hissing sounds.

These havent worked.

Any ideas what could be going on?

 

[Stuckinarut]

Sounds like a motorised valve issue - can you locate this and confirm which type you have? - Usually a 3 port mid position valve (y-plan) or x2 2 port valves (s-plan).

 

[grumpypj]

Thanks for the reply @Stuckinarut

Picture attached. following your response I moved the lever to manual and heating is up and running post that. The valve seems to be A-B style.

I’ve now arranged replacement with an engineer

 

[Stuckinarut]

Thanks for the reply @Stuckinarut

Picture attached. following your response I moved the lever to manual and heating is up and running post that. The valve seems to be A-B style.

I’ve now arranged replacement with an engineer

Great. Glad to be of help.

 

[grumpypj]

Spoke too soon!! Hearing disappeared even with manual override…

 

[Stuckinarut]

Spoke too soon!! Hearing disappeared even with manual override…

Yes it will only work really when calling for hot water. Putting into manual doesn't bring it on, it's a common misconception. If you're competent enough, you could join the 2 switch wires for the motorised valve or put a link in between in the wiring center.

 

[grumpypj]

Thanks a lot. I am unlikely to try that @Stuckinarut ;

been quoted £240 + parts. Sigh