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White Rodgers zone valves

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Dan_L
Dan_L Member Posts: 6
Hi all,
I went on a service call where the homeowner replaced all 3 of his thermostats that weren’t compatible with the 3 wire zone valves. All 3 zones are staying open. I only had one Emerson 1f56n-444 t-stat on my van & wired it in to the basement zone to test it & none of the zone valves reacted. I didn’t think to disconnect the other t-stats.

I got lost after that & wasn’t sure what to do. I thought there was possibly a wiring problem. My office had me leave & their sending someone else out tomorrow. My co worker thinks once the other t-stats are replaced everything will work. If the other 2 t-stats are still connected can that cause the Emerson t-stat to not react? I still get confused with these zone valves sometimes & want to learn what I missed.

I appreciate any help

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  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,767
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    Depends on what zone valve you have. Drive open & Spring return? or drive open --drive close?
  • Dan_L
    Dan_L Member Posts: 6
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    It’s drive open, drive close
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,157
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    Old T87F thermostats had 3 wires needed to operate that zone valve. R was common, W was to open the valve. Y was to close the valve. That worked because when the mercury switch was in the call for heat position, the R and the W was closed and the R to Y was open. As soon as the call for heat was completed, the R to W would open and the R to Y would close. You needed the special sub-base for the T-87 to use it that way. The heating only sub-base that came with that thermostat would not work because it had only R and W. the Y was screwed into a blank terminal that went nowhere.

    That was in the 1950's when life was food and thermostats were analogue.

    If you want to connect that valve to a modern thermostat, you can use a SPDT relay. the thermostat closes the NO relay contacts on a call for heat, then when satisfied the NO contacts open and the NC contacts close to power the closing motor to operate.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • hot_rod
    hot_rod Member Posts: 22,394
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    Is there a relay box involved? That simplifies the Wiring of 3 wire and WR zone valves All zone valves really wire easiest through a relay box 

    if power stealing stats were swapped in, it is best to have a “C” wire at the stat, which is available on some relay boxes on the terminal strip for the t-stats 
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,157
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    Here is a fix you can use with a RIB relay that everyone seems to have on their service truck today.
    The top uses the 3 wire thermostat as designed. The bottom uses the RIB Relay (or any SPDT relay with a 24V coil). This relay has the Common Normal Open and Normal Closed contact that is needed to power the valve closed.

    The only real benefit I see that this zone valve has is that you can use the end switch to close a set of dry contacts like all the other zone valves Terminals 2 and 3 on the valve actuator. OR, you can use Terminals 1 and 3 to power some other relay or gas valve that requires 24 volts.

    1 & 3 = 24 volts
    2 & 3 = Dry contacts (end switch)

    Other than the 24V option, why bother with that contraption?

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • Dan_L
    Dan_L Member Posts: 6
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    Thanks for the replies guys & great explanation with the rib relay. I have a better understanding of it now.

    I think the guy going back today is going to put on new 3 wire thermostats. I'm just not sure if that's going to work since the one I used for a test did nothing. It would be a lot easier if they were the 2 wire zone valves