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Weil McLain SGO optimum pH

Don_175 Member Posts: 130

just had our 5 year old Weil McLain SGO oil fired boiler cleaned etc. we do not use it for domestic hot water in the summer. I had put about a cup of 8 way in it last fall. Drained some water. It cleared up quickly. Sight glass water is very clear. The ph on my meter is around 10.7. Is that too high? We have no foaming or water carryover. I overfilled the boiler past the top of the sight glass and ran it for 20 minutes to purge the oxygen. From what I’ve read here, a ph of 10-11 is ok. Weil McLain says 7-8.5. Should I try to lower it by drawing down and adding fresh water or leave well enough alone?


  • Jamie Hall
    Jamie Hall Member Posts: 23,554

    leave it alone. Chasing pH in a domestic boiler is a bit of a fool's game. If it is anywhere from near neutral (either side) to not foaming, you should be fine.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Don_175
    Don_175 Member Posts: 130

    Great. Thanks Jamie. I appreciate it.

  • ARobertson13
    ARobertson13 Member Posts: 30


    4 years ago I had a conversation with a property owner about water maintenance of her Weil McLain boiler. I explained to her that she should follow the instructions that Weil McLain had in one of their videos for water maintenance. There are two things that I pointed out. One was proper blowdown [surface / bottom] and the other was not to use any chemicals or products to treat or clean the boiler that was not specified by Weil McLain and in the concentration they specify.