Combi boiler - receiver not sending CH signal to boiler?

[losecontrol]

Please help, my combi boiler seems to be working generally (HW fine and CH timer ok for early evening timer).

It’s a Worcester boiler and Plumb Centre thermostat.

But, the early morning CH timer doesn’t fire up the boiler. It used to, but a few months ago it stopped working, only for the first (AM) timer.

it was serviced a month ago and the gas engineer couldn’t find any issues with the boiler and said it seemed to be working on but that the issue above could be due to the thermostat.

However, I’ve checked the receiver abs a green light shows up at the right time but the boiler just doesn’t fire up.

Also, very occasionally, like this evening, when we switch the CH on, the same issue happens (receiver lights up but boiler doesn’t fire up). Normally it turns on fine in the daytime/evening.

Any assistance would be gratefully received. Thank you.

 

[kidgreen61]

Sounds like a faulty receiver, I changed one yesterday for the same reason.
I proved it was faulty by testing for continuity across terminals.
Simple to change, just swap receiver (leave backplate on), and use new sender.