Heat won't turn off

[Júlio César]

I'm using honeywell t8775a1009 which is new and taco zvc403 two zone but one zone won't turn off, it's oil burner and baseboard water system. Any help?

[Account Closed]

You probably need to go to a Do It Yourself contractor forum for help. I am a heating contractor and I work on baseboard systems, but diagnosing a problem without being on the site is difficult because we need to do process-of-elimination.

The first thing I would do is disconnect the wires at the solenoid valve. If the zone is still on then you have a bad solenoid valve.

The second thing I would do is disconnect the wire for the zone at the thermostat. Usually, when one zone does not shut off we find that the problem is either the thermostat is wired wrong, or there is a short, crossed and bare wire inside the wall at the thermostat location. Start with disconnecting the wire from the thermostat for the zone that does not turn off. If the wire is disconnected and the zone is still on then either the wire is crossed inside the wall, or somewhere else.