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M&M 150

Wayne_14 Member Posts: 39
I have a Weil-McLain 788 Steam boiler. Last season we did some work to the system and installed a Boiler Feed Tank along with a M&M 150 Pump control. A couple of months into the season the M&M 150 would stick in the pump feed position so we changed it with a new one. (I opened the old one and it was clean and appeared to be in good working order). Now I am having the same problem again, the bowl is clean and the water is not surging.
Can anyone shed some light on this problem, Any ideas ??

I'll check and try anything.


  • Mark Woll_2
    Mark Woll_2 Member Posts: 67
    did you replace the nipples on which the MM 150 is mounted?

    Maybe there is a blockage causing an improper water leveling in the bowl.
  • Mark Woll_2
    Mark Woll_2 Member Posts: 67
    I believe there is a new capacitance sensor MM150 with no float

    This model would be incapable of sticking.
  • tim smith
    tim smith Member Posts: 2,619
    mm 150

    Are you sure the 150 was sticking on or during cool down I have seen boilers go into enough vacuum and pull right through the check valve of the feed/tank set. Just a ???
  • Robert O'Connor_3
    Robert O'Connor_3 Member Posts: 272
    MM 150

    The suggestions by others may be contributing. If the piping is correct and bowl is clean, there may be other factors to consider. Please contact me to discuss further.

    Greg Roder
    Product Specialist
    McDonnell & Miller
  • Wayne_14
    Wayne_14 Member Posts: 39

    All are clean

  • Wayne_14
    Wayne_14 Member Posts: 39

    Thanks, I'm not sure when it sticks, I always get there after it sticks. Also Steamhead pointed me in the same direction

  • oil-2-4-6-gas
    oil-2-4-6-gas Member Posts: 641
    just had to revive your post--

This discussion has been closed.