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.

replacing a lwco

zepfan Member Posts: 358
is there a time when a low water cutoff, even it is working right should be replaced? i read recently that a float type lwco should be disassembed and cleaned every ten years (would make more sense to replace it at that point) and a sensor type, the sensor should be replaced every eight years.has anyone else heard this?


  • Rod
    Rod Posts: 2,067
    Replacing the LWCO

    Hi-  The following is the recommendation of McDonnell & Miller regarding inspection and replacement intervals.

    Float Type- On the float type M&M 67, it is recommended that it be dissembled and inspected annually and completely replaced every 10 years

    Probe Type-  It depends on the probe type. Generally Inspection and cleaning annually, Replacement of the probe itself at ten years and the control at 15 years.

    Attached below is a PDF with the M&M instructions. For more information look up the publications cited in the PDF.

    - Rod
  • Hap_Hazzard
    Hap_Hazzard Member Posts: 2,787
    Always seemed dumb to me.

    If you take it apart and inspect it every year, you replace it when it looks like it may not last another year. If it lasts ten years, it's a keeper. Why throw it out if it looks good, especially if you just replaced the float last year?
    Just another DIYer | King of Prussia, PA
    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
  • Rod
    Rod Posts: 2,067
    LWCO Replacement

    I understand what you are saying but since it is a safety device, I think you're better off just replacing it whether or not it is still looks good at the 10 year point. M&M has reasons for setting this limit other than just to sell you a new LWCO! :)  It's sort of like changing the timing belt in your car engine even though it looks fine. The catastrophe caused by failure is economically far worse than replacement.

    - Rod
This discussion has been closed.