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Location of Low Drain for Weil-McLain Boiler


I have a Weil-McLain EG55PIDN Series 4 that is running well. I just finished some basic maintenance on it, including draining water, new sight glass cocks, unclogged pressure valve pigtail.

The previous owners did not take care of anything in the house, especially not the big scary boiler in the basement.

I was able to find the drain on the side of the boiler, but not able to locate what I have heard some people refer to as the "low drain". Below are some photos of my boiler system, and I was hoping someone might help me identify where the low drain is, if I even have one.

Here are some photos:


  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,844
    edited December 2022

    This is where it should go

    The drain valve on the boiler will empty the boiler. It will not get the water out of this wet return. The full size cap is there for maintenance to clean out the wet return. If that has sludge in there, you can get a brush in that pipe easily to clean out the pipe. perhaps even put a hose inside there to flush out that sludge.

    You can replace that with a reducing coupling and a drain valve if you like. If you do annual maintenance there, you may not need to ever use a brush in there to get the gunk out. But this first time in years, you will find some nasty black mud.

    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics