Zone Valve Problem

StevenHB

I found that one zone of my heating system was getting excessively hot. We've made no changes to the system recently, so I suspect a problem with the zone valve.

Question: How do I differentiate between a failed zone valve controller (i.e. a failure in the motor that opens the valve) and a failure in the valve itself?

Darrell

Tag and pull the wires off the power head. If they are all daisy chained together you may have to keep the 2's and 3's together to maintain the circuitry to the other zone valves. Then twist the powerhead and pop it off. Wait for several hours to see if the flow to that zone stops completely. If the zone stays hot, then the zone valve body is hung open and needs to be rebuilt. If the zone goes cold, then the body is good. Stick a new powerhead on it and you're probably back in business, providing the t-stat is good.

Joe Mattiello

Joe Mattiello

Thank you, for using taco products. For your reference I attached a general zonevalve trouble shooting guide. However, to determine if the failure mode is actuator, or valve seat assembly, you first need to validate 24 volts at terminals 1, and 2 to see if the valve opens after approximately 1.5 minutes. If the actuator gets hot, most likely the actuator is fine. Another way to know if the valve is open; move the manual lever to the manual mode, if you have little to no resistance, the valve is open, a lot of resistance, valve is still closed. Next; kill the 24 volt power supply to the actuator wait a couple of minutes for the actuator to cool, remove thermostat wire from terminal 1 and twist actuator ¼ turn to remove actuator. Take a blunt object and depress the piston on the valve seat, if you can depress it with some force and the valve opens the valve is good. If you can not depress it the valve seat needs to be replaced. Hopefully this helps you with your field diagnostics.

StevenHB

Thanks!

It turned out to be the power head. I replaced it and things are good again. Thanks for your help.

The $60+ for the new power head seemed like a lot of money (but certainly less than having our repair guy in to do it - and we've had some trouble getting him to show up).

StevenHB

Thanks

Joe, thanks for your help, too. I don't think that I was able to find your attachment on the Taco website. Is it posted there?