Hi. We have had our nest heating setup for a few years now. There are 2 zones/thermostat’s. 1 for radiators upstairs /living room and 1 for underfloor heating in kitchen/diner. It has all run perfectly, but suddenly we are getting an issue where the hot water is not working. The heating is all fine, but every time the hot water comes on it opens the electronic zone valve to the hot water tank and then it closes again after about 2 minutes. This means we end up with no hot water in the morning even though it’s scheduled to come on. The only work around currently is to manually open the valve with the switch on top while the heating is on and it fills the tank with hot water. Even then the valve keeps trying to close itself even if the hot water is set to be on.
I have replaced the thermostat on the hot water cylinder and that had no effect. The legionella function is not on so it’s not that either. I have tried resetting he nest thermostats completely but no luck. The wiring all seems to look fine - ie no wires have become disconnected and it all worked before.
I am getting a plumber to replace the zone valve which I have just purchased but worried it might not solve the problem. Does anyone know if they can malfunction and close randomly? I really hope that might be the issue but really not sure. Thanks in advance as I am tearing my hair out to work out what’s wrong!
