Last week I did a diy install of the 3rd gen Nest thermostat replacing my programmer with the Nest heat link and from my understanding I have a Y plan system which is how I wired it in following the manual instructions.
Everything is working fine you will be pleased to hear but the other night I was woken up by the Grunfoss pump running. I checked the the HW and CH and they were both turned off so I then turned down the cylinder stat and the pump stopped running? This is an intermittent problem and has happened a few times at night.
I noticed when I wired the heat link up it didn't have a CH off wire to attach but as my old programmer didn't have it I left it as is.
So my question is do you think I've made a mess of the wiring or are these symptoms likely to be a failing cylinder stat or even a failing PCB?
I have a Prima F boiler and the PCB was replaced about 2 years ago and the 3 way motorised valve was replaced about a year ago.
Any advice is much appreciated
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