2 zone heating 1 not turning on boiler

Scruff

I have 2 zone (up stairs and downstairs) heating with timer switches and TRVs to a gas boiler. Downstairs zone has stopped working. I presumed it was the timer switch so swapped it out but the problem still persists. There is power going to the motorized valve for the zone but boiler still not turning on. Only way i have it working at the moment is to have the valve set to manual override open and using the upstairs zone timer to turn on the boiler, so acting as a single zone. I cant see anything obviously wrong with the wiring aside from it being a complete mess as i also have solid fuel stove with back boiler, but no wires lose.

Wearb

Most likely the end switch on the zone valve has failed.

I presume that that zone heats if turned on at the same time as the other zone?

Scruff

Yup, that's correct. I just have it on manual open so as to only have to set 1 timer for now but when manual was off the zone still works on the valve but needs the other zone timer to start the boiler.

Can they be replaced without having to drain the system and getting a plumber?

Wearb

Almost certainly an end switch problem. (Also could be loose or broken wire) You can most likely get a new head for the valve. Take a picture of it and call around to your local plumbing supplier. Chadwicks and Heatmerchants are good bets, but most plumbing shops will have them, unless it's an odd one.

meercat

Also check the wal thermostat is turned up. I’ve seen the auxiliary circuits controlled by the stats in some installations

Scruff

https://www.boards.ie/discussion/comment/119957102#Comment_119957102

Cheers but dont have any, just timers for the zones.

https://www.boards.ie/discussion/comment/119955377#Comment_119955377

Motorized valve in question is a Myson MPE222. Heatmerchants and Amazon stock replacement actuators so hopefully will be sorted soon. Thanks!

Scruff

Thanks @Wearb!! 15min job to replace the head unit and zone is back working properly just in time for the cold snap.