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Low Water Cut Off

AthanaAthana Member Posts: 88
*Is a Cycleguard supposed to shut the Boiler down when water gets too low or is it another box that does that?
Cause when water gets low nothing is shutting Boiler down.
*When water gets low the Cycleguards two little lights go on and asks for water..which automatically goes on..but I have the water feed off cause i am worried Cycleguard will not stop feeding water(as it once did in the past) So I go check water level every few days.
The other day I went down and water was very very low the two lights asking for water on Cycleguard were on, so I turned on feed and added more water to boiler..water went up to level ..but lights did not turn off on Cycleguard.
Boiler would not turn on for some time..but eventually went back on..Is this Cycleguard unit sounding faulty?


  • John RuhnkeJohn Ruhnke Member Posts: 880
    Cycle Guard has a delay of 15 sec or 30sec so.

    That said I would get some sandpaper, turn the power off and check and sand contacts. See if any seem sticky.

    If that doesn't work you might need to replace it.
    I am the walking Deadman
    Hydronics Designer
    Hydronics is the most comfortable and energy efficient HVAC system.
  • AthanaAthana Member Posts: 88
    But John is that the unit (Cycleguard) that shuts Boiler Down when water level gets low?
  • John RuhnkeJohn Ruhnke Member Posts: 880
    You can trace the wires and see where they go. If something goes down to the burner then yes. If not no. It could also be wired wrong.
    I am the walking Deadman
    Hydronics Designer
    Hydronics is the most comfortable and energy efficient HVAC system.
  • Jamie HallJamie Hall Member Posts: 14,916
    The Cycleguard is supposed to shut the burner down if the water is too low, yes. If it doesn't, you have a major safety issue on your hands -- and if just cleaning contacts doesn't work, then honestly you should turn the boiler off at the switch until you can find out why. A dry fired boiler can ruin your whole day.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • AthanaAthana Member Posts: 88
    Thank you..Is there a more dependable replacement for Cycleguard? I have two Boilers working together the issues seem to be with the Cycleguard on one of the Boilers.Do both Low Water Cut off need to be matching?Thank You
  • nicholas bonham-carternicholas bonham-carter Member Posts: 8,358
    edited October 2019
    To verify that the LWCO is cutting off on low water:
    1. Turn off the boiler by its switch, and turn off the water valve in front of the auto feed.
    2. Set up the thermostat high, so it will fire when turned back on.
    3. Drain out the boiler water to the bottom of the gauge glass.
    4. Turn on the switch-the boiler should not fire.
    5. Turn on the auto feed, and wait for it to fill the boiler. When the correct level has been obtained, the boiler should fire.
    6. Set the thermostat back down.
    7. If the LWCO fails on #4, and 5, call a technician who is familiar with hydronic systems, as not every plumber is.
    8. I suggest going with the model of LWCO which does not cut off the burner every few minutes, (ie. Safguard, by the same company). It should have a water meter on it.—NBC
  • SeanBeansSeanBeans Member Posts: 483
    If you have two boilers running together I would probably have a secondary LWCO with manual reset

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