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McDonnell Miller PS802 LWCO not sending feed signal to WF2-U-24

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petec88
petec88 Posts: 24
in THE MAIN WALL

Hi, I think I am having issue with my McDonnell Miller PS 802 LWCO sending a signal to the Unimatch water feeder. The LWCO installed on my dunkirk boiler seem to be working. The green light is on showing power. When I drained the water enough, the red light turns on indicating low water, and when I manually add enough water back-in, the red light turns off. This appears to me to eliminate that it is a probe issue.

On the water feeder, when I manually press the feed button, the green light on the water feeder comes on and water is fed into the boiler. However, the issue seem to be the green light not turning on when the water level is low from the LWCO. The wiring setup current from the LWCO to Unimatch is N = 2 (N on PS802 and 2 on Unimatch); C = 3; W = 1

What should I test with the multimeter to determine whether it is a LWCO failure or Feeder failure? Is there a way to manually provide the signal on the "W" wire to test the feeder?

Thank you for your help!

Comments

  • EdTheHeaterMan
    EdTheHeaterMan Posts: 12,842
    edited 12:28AM

    Is there a time delay in the water feed? That comes standard on many water feed systems to prevent flooding. If your condensate takes a long time to return and your feeder has added water in the mean time, when the condensate does return the boiler water line may rise too high. When you install a new water feed valve, you want to look at the directions and see if you need to increase or decrease the delay to prevent flooding and reduce waiting time for the boiler to start steaming again. It can take a couple of tries to get it right,

    Edward Young Retired

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

  • petec88
    petec88 Posts: 24
    https://forum.heatinghelp.com/discussion/comment/1906982#Comment_1906982

    1-2 minute time delay but waited 30 minutes and no go. The red light on the LWCO remained on the entire time but the feeder never turned on. After 30 minutes, pushing the manual feed I was able to get the water level back above the probe for the red light to go back on and heat to come back on for now.

  • 109A_5
    109A_5 Posts: 4,607

    Assuming the 24 VAC models. At the LWCO removing the wire on the W terminal and touching it to the C terminal long enough for any delay to expire should activate the feeder.

    image.png
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • EdTheHeaterMan
    EdTheHeaterMan Posts: 12,842

    Your wiring may not be correct. Can you take a photo of the wires and how they are connected to each control then post those photos here?

    Edward Young Retired

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

  • 109A_5
    109A_5 Posts: 4,607
    edited 5:13AM

    I assumed it worked at some point but that may not be true.

    If you want to test with a meter, with the LWCO calling for water I would expect there would be 24 VAC between N and W terminals at the water feeder.

    image.png
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System

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