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Understanding Zone Valve

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zvalve
zvalve Member Posts: 83
in Gas Heating
I think I have the problem diagnosed but need some confirmation from the heatinghelp.com community. I took the power head off the zone valve which was overheating the zone and turned the shaft manually in two position, which I believe were closed and opened all the way clockwise and all the way counterclockwise. Both of these positions move the shaft only about a quarter turn. In both positions heat poured by the valve to the second floor so I assume valve is no good is this correct? Also in the photo is the valve closed?

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  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,006
    edited April 2022
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    Looks like a Honeywell. Yes, the valve stem moves very little and the valve may still be good. You can't really tell if the valve is working properly without the operator installed as the operator exerts constant pressure when closed.

    Replacement operator here.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
    mattmia2
  • Zman
    Zman Member Posts: 7,569
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    If you buy the entire valve, you can start by replacing the powerhead. If that does not fix the problem, you can drain the system and replace the guts without unsweating anything.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    mattmia2
  • heathead
    heathead Member Posts: 234
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    I had one that the ball was broken inside. Still looking for half of it. It has a rubber ball the closes on the seat to stop the flow. As Alan and Zman have said try power head if that doesn't fix it replace the insides ie ball and shaft. You don't have to solder anything just release the pressure and drain, then pull those four bolts.
    Alan (California Radiant) Forbeszvalve
  • zvalve
    zvalve Member Posts: 83
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    Thanks everyone, replaced powerhead and the zone experienced some warming but not much hot water was flowing by so this zone valve went from causing the zone to be overheated with the old powerhead to be barely warm with the new powerhead. Hence it seems like the shaft and ball is no good inside the zone valve. Will try to rebuild it as heat head suggested
  • Aluvaboy
    Aluvaboy Member Posts: 29
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    zvalve said:

    Thanks everyone, replaced powerhead and the zone experienced some warming but not much hot water was flowing by so this zone valve went from causing the zone to be overheated with the old powerhead to be barely warm with the new powerhead. Hence it seems like the shaft and ball is no good inside the zone valve. Will try to rebuild it as heat head suggested

    When you open up the valve for rebuild, examine the rubber ball closely. If it is pitted badly, it is an indication that somehow oxygenated water is getting into your system. Honeywell says that this ball will deteriorate fast if oxygenated water enters the circuit constantly. So I would check to see if there are any leaks in the circuits as well which allows water to be constantly replenished through the fill valve.
    Alan (California Radiant) Forbes

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