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Blow down sequence

I am a homeowner new to steam heat, and this is the second question I am posting. We have a Weil-McLain boiler that has both a McDonnell & Miller 47-2 LWCO + water feeder, plus a McDonnell & Miller 61 LWCO. Our local HVAC service provider has been trying to help me troubleshoot what appears to be frequent excess water in the boiler. The level in the gauge glass is often about 3/4 of the way full when the boiler is not firing, and this is close to 2 inches above the ideal water level line. I have not seen the level higher than that, but I have had some instances where one or both of the main vents in the basement spit water out of them, and this doesn't happen when the water level is lower. I have been blowing down both of the McDonnell & Miller devices weekly, flushing until the water is relatively clear. Typically I do this on the 61 device first, and then on the 47-2, for no particular reason. The last time the contractor was out to the house I was at work so couldn't speak to him directly. But he told my wife to have me blow down the 47-2 first, then the 61. I am not questioning him, but just trying to understand the logic behind this. I assume the goal is to not "trick" the system into thinking the boiler needs water when it really doesn't, causing it to end up with more water than it needs. Can anyone explain his reasoning, and is it correct? Thanks,


  • pedmec
    pedmec Member Posts: 975
    Could be a lot of things causing the water level issue. Have you checked the level at which 47-2 sits to make sure its installed at the right height? Can you send a full pic of boiler.
    EBEBRATT-Ed Member Posts: 15,529
    It doesn't matter which one you blow down first or second. The only thing that matters is if both controls are installed at the right height, the piping connecting the controls is clean and that the 47-2 and you manual fill valve are not leaking by
  • shakingthrough
    shakingthrough Member Posts: 8
    Thank you both. I am away for work for a few days, but will send a few photos toward the end of the week when I return home.