Honeywell programmer / wireless thermostat problem

21 Oct 2022
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United Kingdom
So I've used a wireless thermostat to activate my heating since installation, but it's just stopped working (Blank screen, no new battery's fixed fixed it)

The wall mounted programmer screen flash's no signal, like it's searching for the wireless thermostat, I cannot turn the heating on at all via the wall mounted programmer when it's like this, on any setting(Cont/auto), however, when I switch the system off and back on at the mains plug, green lights will come on, the no signal is gone and I can turn the heating on at the wall mounted programmer, this seems to fix my problem for a short time, but the programmer will get the flashing no signal again and start searching for the wireless thermostat.

Is there anyway to disable the wireless thermostat mode from the wall mounted programmer so that it stops trying to search for it and giving me the no signal problem?

I've included some pictures (honeywell st9420c programmer and the thermostat)


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