Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Weil-Mclain mgb-5 steam boiler

Does anyone have any info on WM's mgb series gas boiler? Looking for ratings (especially the mgb-5), and when it was discontinued. Thanks in advance.


  • Steamhead
    Steamhead Member Posts: 16,826
    From an old W-M boiler CD-ROM I have:

    The MGB-5 Series 1 was rated 680 MBH input and 544 MBH Gross Output, and was made between April 1973 and January 1984.

    The MGB-5 Series 2 was made between January 1984 and December 1985. It was rated 680 MBH input and 510 MBH Gross Output.

    Not sure why the Gross rating was lowered, but there it is.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • AJCimino
    AJCimino Member Posts: 28
    Thanks, Steamhead. That's what I was looking for.