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.

Remove LWCO Probe

Gearing up for 2nd season of steam heat as newish home owner.
Read the book and doing some basic checks/maintenance including cleaning the LWCO probe sensor.
But, can't figure out the right way to remove it and don't want to do more harm than good.
It's a Safgard 400 series probe type. I have the cover and outer box removed from the side of the boiler but not sure if the probe assembly in it's entirety gets removed from the side of the boiler, or if I should be able to pull out the probe itself to wipe clean then reinsert?

If it's annual maintenance seems like it should be fairly straight forward but bit nervous of screwing it up.

Thanks for any tips.


  • Steamhead
    Steamhead Member Posts: 16,832
    The entire probe is screwed into the side of the boiler. You may need a rather long wrench- maybe 24 inches or so- to get it to turn. Make sure the water is drained down below the level of the probe or you'll get a waterfall.

    Check the porcelain insulator that separates the probe from the brass plug it mounts in (just visually, do not try to take the probe out of the plug). If it has deteriorated, replace the probe.

    When re-assembling, put some anti-seize compound on the threads. Once it's back together, before re-filling the boiler, turn on the power and see that the unit goes off on low water as it should.

    If you find anything out of the ordinary, call a pro.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • djd
    djd Member Posts: 18
    Awesome - thanks for clarifying!