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New LWCO seems to be missing something.

I have finished my first steam boiler install and I'm starting it up. The LWCO, McDonnell Miller 67, is calling the auto fill valve. Im watching the water level rise up and over the top of the watch glass. This is when I shut it down. The LWCO has no terminal 3 available, its blanked. After checking my wiring, I look into the switch and see the roller that should actuate the switch not able to reach the rocker. On an old, decommissioned switch I see where the roller would ride in the notch, but this new switch seems not to have a lower surface to make the switch. Its a brand new device. I think this is assembled with non integrated parts.

The instruction manual was quite thin. Can anyone offer advice to me?


  • John Ruhnke
    John Ruhnke Member Posts: 882
    Put it back together so it looks like you never took it apart. Take the 67 off of the boiler. Take it to the supply house. Explain that it wasn't working. Get new one under warrantee.
    I am the walking Deadman
    Hydronics Designer
    Hydronics is the most comfortable and energy efficient HVAC system.
  • retiredguy
    retiredguy Member Posts: 930
    If the switch does not have a #3 terminal, then that switch is for a manual reset control. You need an auto reset device. The number for the correct switch is #309100. or tell the supplier that you got the wrong device . You need an auto reset device.
  • Boilershepherd
    Boilershepherd Member Posts: 29
    Thank you very much. This unit was equipped with and auto feed after the unit was delivered.
    I'm back on track.