Heating zone not activating

chrismcd1

I have an oil boiler, with a taco 6 zone switching relay, Honeywell hz311 zone control panel on air handlers. Zone lights for the 2 zones controlled by the zone control panel are lit as the corresponding thermostats are calling. The corresponding zone light on the switching relay will not come on, nor will the air handler or the zone pump. I replaced the Honeywell zone control panel (EMM-3) with the HZ311 thinking it was the panel, but same result.

Jamie Hall

Before you throw any more parts at it, use your multimeter to find out where power isn't -- then look for why.

chrismcd1

No power on 120 leads to pump for that zone, there is 28v on the thermostat leads though. If I jump the thermostat leads, the red zone light comes on and the circulator pump comes on. Air handler does no though.

Jamie Hall

If there's 28 volts between the two thermostat leads, the thermostat isn't calling -- or you have an open in one of the thermostat wires (or a bad connection -- same thing really). Remember that in essence a thermostat is just a switch: closed to call, open to stop.

Without seeing the wiring, I can't speak to the air handler.

Big Ed_4

Air handler fan is normally controlled with a sensor on the return if heating coil on air handler . First check if return to boiler is hot

chrismcd1

Lol, the air handler wasn’t coming on because there is a panel switch and I had a panel off the cabinet. So...if I jump the thermostat leads in the switching relay then the light comes on, power is supplied to the pump and everything works. So what does that mean?

Jamie Hall

If you jump the thermostat leads in the switching relay, then the switching relay thinks that there is a complete circuit from one terminal to the other (there is -- your jumper). Now when the thermostat calls, it is supposed to close and make a similar complete circuit, only through the thermostat wires and the thermostat. So... if it works with the jumper, you are limited to an open in one of the two thermostat wires, a bad connection in one of them or at the thermostat -- or the thermostat isn't switching. Easy to trouble shoot.

chrismcd1

Jamie, Little more info. There are 2 zones and therefore 2 thermostats on this one heating loop. There is a Honeywell zone control panel in the mix, which I replaced to no avail. The zone lights on the zone control panel were both green showing both thermostat are calling for heat. So to troubleshoot the open you are referring to, I don’t know where to start.

Jamie Hall

Start at the relay thermostat terminal, where you know it works. Take that wire pair and trace it back. Connect the two wires together at their ends there (take them off whatever they connect to first). Does the system work? Ok then, the wires are fine. Now figure out what's next back in the chain. Um... no. solid state. Sigh... well... and you note that the zone light on the controller doesn't light. That tells you that that zone isn't getting the word, doesn't it? So try jumping the input terminals on the controller for that zone. They would be R and W. Success? Ok, then the problem is in the wires from the thermostat to the controller, or in the thermostat itself. Try tracing the thermostat wires back, and disconnect them at the other end from whatever and connecting them together. If the jumper worked, but the connection doesn't, the problem is in the wires. If connecting the wires works, the problem is likely in the thermostat or its base.