Boiler not switching on sometimes

ION08 · 18-10-2016 11:38PM #1

Hi wondering if anyone can shed some light on my problem

I have a Vokera Mynute 24 SE boiler and yesterday I got a NEST smart thermostat fitted.

I find that now when i try to turn the boiler on from the Nest control it gives me a Red flashing led light.

I have check the manual and it says : "Alarm High Limit Thermostat"

If i reset the boiler (turn off/on) from the boilers own control knob it fires up ok with green Led light

Thanks for any insight

ION08 · 19-10-2016 05:15PM

Heres the Error description from the online manual:

can anyone give me more insight into what this means?

Pete67 · 19-10-2016 05:32PM

It means the boiler has overheated. If it happens on shutdown and did not happen previously I would hazard a guess that the Nest has not been installed correctly, and is switching the mains supply to the boiler directly rather than making the boiler run control terminals. The boiler should have a permanent mains supply so that it can run a cool down cycle once the run signal has been removed. If the cool down cycle is not working properly you will often get an overheat alarm next time the boiler tries to start. This can also lead to early failure of the boiler's heat exchanger.

Check if the boiler pump and fan continue to run for a few minutes after you switch off the heating via the Nest? If not, the wiring is not correct.

Boiler not switching on sometimes

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