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Power requirements for Honeywell zone valve actuators

PEvans
PEvans Member Posts: 142
in Strictly Steam

My steam system has two zone valves (globe) operated by Honeywell M644A motor actuators. One valve keeps sticking open, and this is a bad day because the valve position switch is what turns on the primary boiler control.

On these actuators there is actually a "close" coil that is energized to close the valve.

I have tried spraying the valve shaft with PB Blaster and it helps for a while.

I am wondering if the 120V/24V transformer is tired and not generating enough current to operate the valve. The motor nameplate says 24V, 60Hz, .69A, 15W.

Does anyone have a sense for how much power these motors need to work reliably? I think I could get a new 24V transformer rated at 40VA (roughly 40W) or maybe higher.

Comments

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 10,329
    edited March 14

    Honeywell recommends no more that 4 of the V8043 *** zone valves on one 40 VA transformer. I need to look uop the other motor.

    I have seen that actuator used for gas valves and also for modulating power burners to adjust  the combustion air inlet.   I am not familiar with the internal workings of the actuator to be able to tell you if a new transformer will solve your problem.   I have not heard of a transformer losing power gradually with age.  My guess is that the actuator is getting old and the sleeve bearings are worn.  It is probably time to look at a replacement actuator.  

    Edward Young Retired

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

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 17,466

    If I am not mistaken those motors can run on a 25va transformer. I would suspect the motor or linkage or valve packing is binding up.

    I don't think the M644 is made any longer but they do have a replacement. Seems more like a valve problem.

  • 109A_5
    109A_5 Member Posts: 2,285

    Did you verify the appropriate limit switch is working correctly ? Transformers work until they don't, they don't fade away.

    image.png
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • PEvans
    PEvans Member Posts: 142

    @EBEBRATT-Ed what is the replacement for an M644?

    (Yes, these valves and actuators are old. I found a date on one of the valve position switches of 1963)

    @109A_5 good point about the limit switches. That would be hard to check since there is not good access to the actuators from above, and they open from the top.

    @EdTheHeaterMan my two valves each have their own 24V transformers to drive them. Of course I do not know tbe ratings. The transformers are not new and could be contemporary with the actuator.

    It would be major surgery to replace an actuator with anything other than a like for like drop in replacement,. It would be major major surgery to replace the valve itself.

    Thanks…

  • 109A_5
    109A_5 Member Posts: 2,285

    " That would be hard to check since there is not good access to the actuators from above, and they open from the top. "

    With the actuator stopped and powered down at each limit and the transformer secondary disconnected, you could use an Ohmmeter to compare the circuits. T1 to B and T1 to W, I would expect the resistance to be the same with either path.

    Also I would verify the proper 24 VAC is getting to the correct terminals, if you have not already.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 17,466

    You should call Honeywell or a supply house like Supply House.com or Kele associates etc. Give them the information and they will match it up.

    But you have to be sure the valve is ok first. Yoou don't want to put the new motor on and have the same issue.

    If they are old you may be better off with new valve and actuators. Kele could help with that. They are in TN

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