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Should the low water cut-off be installed horizontally?

Paul84 Member Posts: 3
I hope someone can verify the following. I am not an expert, I just recently changed my plumber and the new one pointed out that my low water cut-off Guard Dog is installed incorrectly. He said that in the current setup it is useless and is only a decorative piece.

Apparently it needs to be installed horizontally instead of vertically.

Can anyone confirm this? I wanted to double check before I will call my previous guy and ask him to fix the job. Thank you for your help!

The model is: GuardDog RB-122-E

Part No. 144676


  • R Mannino
    R Mannino Member Posts: 439
    The Instruction Manual

    says vertical is acceptable.


    page 2
  • icesailor
    icesailor Member Posts: 7,265
    Lower Water:

    Your new plumber needs to bone up on his knowledge so he knows what he is talking about.

    On a hot water boiler like you have (its not a steam boiler) the water level should always be completely filling the system. Only when the water level gets below the probe does the control become active and shut down.  What's more important is if he asked you when the last time you hit the test button to see if it stopped the burner.

    It is amazing and astonishing how much someone can learn just by reading the instruction manual. You may think you are stupid before you read one. But after reading one, you have to come away just a little smarter.
  • Ron Jr._3
    Ron Jr._3 Member Posts: 603
    Not sure

    about mounting the probe in a dead end pipe ............ 
  • icesailor
    icesailor Member Posts: 7,265
    Dead End Pipe:

    The PRV is installed in the correct position as per instructions. Its better than having it on top where the LWC is located. Usually there is an air vent there. That tapping is in a place in the boiler that is designed to collect air. If that nipple and fitting fills up with air, the LWCO shouldn't work. It doesn't depend on a float, it depends on the conductivity of the fluid for an electrical current from the control to go to ground through the fluid. If there is no fluid, there is con connection. The LWCO should sense that and shut down. As long as the tip is covered, it should work.

    It may not be the best location but a lot of boilers don't give you a better place to locate it.
  • Bob Harper
    Bob Harper Member Posts: 969
    other issues

    That foil tape needs to come off the vent connector. Even though it carries a UL 181 listing, it is approved for warm air ducts and not vent/ chimney connectors. More specifically, it is prohibited by NFPA 211 because it conceals the condition of the pipe. If you think you need to seal the crimped joints, use furnace cement but since this is negative pressure venting, this should be unnecessary.

    If the boiler mfr. does not specify a minimum water level then you can place the LWCO anywhere above the boiler you like. This is a little higher than typically found but doesn't hurt.

    When you drop the water in the boiler to replace the pressure relief valve every 3 yrs you can remove the LWCO and service the probe unless the mfr. requires a more frequent schedule.
  • R Mannino
    R Mannino Member Posts: 439
    They Trap Air

    that way..................how'd you know Ron?
  • Ron Jr._3
    Ron Jr._3 Member Posts: 603
    Hey Ron !

    Had a job fail inspection with the probe piped like that

    ( not my install ) .

     And it is an amazing place to trap air ! 
This discussion has been closed.