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McDonnell & Miller LWCO 63M with manual reset switch

frankie55 Member Posts: 2
edited October 2020 in THE MAIN WALL
Hoping someone can help me out here.
I installed a Weil Mclain 900mbh gas steam boiler 3 years ago.
The other day on cleaning and testing for the upcoming season, the manual reset doesn't work when we
open the 3/4'' ball valve to clean out the chamber.
The boiler shuts down briefly but turns back on again.
I thought this switch needs to be manually reset before the boiler comes back on again.
Should i replace the the 2M switch or is there a underlying problem.
Anybody else had a similar problem like this.


  • tim smith
    tim smith Member Posts: 2,738
    Need to open up low water vessel, clean out, probably scaled up and not allowing it to drop all the way. We open and clean these annually. 3yrs, probably pretty blocked up.
    EBEBRATT-Ed Member Posts: 15,302
    It could be the switch. If it shuts the burner down it should lock out the burner until the switch has been reset
  • frankie55
    frankie55 Member Posts: 2

    I changed out the S2 Switch and everything works fine.
    Burner locked out.
    I think the heat of the chamber finally got to the reset mechanism.
    They recommend changing out the switch every five years any ways.
    Thanks for your help.