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One zone not working - valve issue?

tapritch
tapritch Member Posts: 3
in Gas Heating

Hello,

New homeowner here. One of our zones is getting no heat. It was sometimes working last winter and now not at all. The HVAC professional who came suggested it might be the zone valve but also didn't seem that knowledgeable so I'm asking here.

I have limited understanding but here's what I know:

  • We tried to switch the zone valve to manual and there is resistance. The thermostat is turned up and should be calling for heat.
  • When we switched the value to manual, the valve opened, water flowed, and heat came out of the baseboard heaters.

Do we need to replace the valve? Or is this an issue of the communication between the thermostat and the valve? (The resistance is the part that's making me question if it's the valve)

Are there other things we can easily test to diagnose the problem?

Thank you!!

Comments

  • 109A_5
    109A_5 Member Posts: 1,883

    Hello tapritch,

    Sounds like the actual valve works. What needs to be determined is if is is an electrical problem or if the zone valve motor has failed or can't overcome the mechanical resistance. If you have a multimeter is there 24 VAC across the zone valve's motor terminals or wires during a call for heat ? How does the mechanical resistance compare to other zone valves, excessive resistance may be stalling the motor.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • mattmia2
    mattmia2 Member Posts: 11,120

    Picture of the valve? If it is the type with a manual lever, that moves the gear train that the motor moves so it has some resistance to manually open the valve.

  • tapritch
    tapritch Member Posts: 3

    @109A_5 Thank you! I unfortunately don't have a multimeter but I'll see if I can borrow from a neighbor and check the current. The mechanical resistance seems the same as the other zone valves. One moves freely at the moment, and the other 6 have the same resistance. (Although a bunch are calling for heat so I'm getting confused…)

    @mattmia2 Here's a picture of the valve

    IMG_1868.jpg
    IMG_1870.jpg

  • mattmia2
    mattmia2 Member Posts: 11,120

    check the voltage, there should be 24vac across the yellow wires when there is a heat call. If there is no voltage it is somewhere in the controls. If there is 24vac and the connections are good it is the zone valve motor.

  • tapritch
    tapritch Member Posts: 3

    @mattmia2 That's very helpful - thank you! We'll do that and see if we can diagnose the problem. Appreciate it.

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