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1890 Victorian House Museum, Low Water Cut Off maintenance

NealJ Member Posts: 43
So, reading though all of the literature in the Boiler ‘packet’, I find the booklet for the LWCO, and it says besides flushing it weekly, that it should be taken apart annually and cleaned. I’ve watched the local boiler guy do our annual maintenance and he’s never touched it. What does it take to disassemble and clean this thing? Do I need to drain down the system below the sight glass, or can I valve out the sight glass (with the system shut down). Should I wait for summer, or can this be done at any time? I ordered new gaskets for the bottom & side.


  • AdmiralYoda
    AdmiralYoda Member Posts: 627
    You can do 90% of the cleaning without removing it from the boiler. The drain (bottom) and float/switch assembly (right) come off with 4 bolts. Then you can remove the two small plugs.

    The float will probably be covered in gunk. Take the assembly to the sink and scrub it clean. With a variety of brushes scrape and clean the inside of the LWCO assembly. Use a round brush to go through the plugs and clean the pipes connecting to the site glass.

    Order some new gaskets for the drain and float section and put it back together. Be sure to make sure the mating surfaces are 100% squeaky clean or they will leak.

    When I was a new steam homeowner I tested the LWCO and the float was stuck. I did this and the LWCO now works great!
    EBEBRATT-Ed Member Posts: 15,517
    If you blow it down weekly with the burner running and the burner shuts off and then restarts and you get a decent flow of water, then the control is working, and you can delay maintenance until warmer weather & you have the parts
  • ethicalpaul
    ethicalpaul Member Posts: 5,701
    If you keep reading in the manual you'll see they tell you to replace it after 10 years, too. How old is that one?
    NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el
  • NealJ
    NealJ Member Posts: 43

    If you keep reading in the manual you'll see they tell you to replace it after 10 years, too. How old is that one?

    I saw that (!). It’s 7 or 8 years old now.
  • NealJ
    NealJ Member Posts: 43
    Thanks guys. The reason I started looking into it was that the flow of water out of it when I blow it down has changed. It used to start and finish with good force. Now the force of water seems to diminish after the first blast. It still seems to work properly in that the boiler shuts off & restarts.
    JUGHNE Member Posts: 11,060
    That LWCO gets it's water from the same port that feeds the sight glass.
    Not uncommon for that opening to get partially plugged.

    IIWM, I would drain the water down below the bottom of the sight glass and remove the lower SG valve. You unscrew the packing nut and then the valve will screw out of the body.

    You can use one of the glass protector rods to assure that port is open. Or something larger if it will fit into the opening.

    There is a "drain" valve on the bottom of the sight glass lower valve.
    I remove that and install a 1/4" mpt X male garden hose ball valve.

    Supplyhouse.com has them for about 16 bucks, #521-61-04 made by "Dahl".
    There are a few SG drains that are 1/8", but most are 1/4".
    This lets you blow down the sight glass to assure that you see the actual water level.

    You mentioned a bottom gasket, I assume that is for the blow down valve assembly,
    Those screws/Allen bolts may twist off if you try to remove them.
    I would leave it alone. If the existing valve will not seal, you can just add another below it.

    Come spring you can open up the LWCO, the most work will be cleaning up the faces where the gasket goes. I have been painting gaskets with Anti-Seize compound for the next clean up. More experienced ones here advised to do that.
    I will find out next season how well it works.

    The float has an accordion flex on one end of it and if too curded up in will not flex as well. And also a delicate portion of the float. A toothbrush cleans it up well under running water.

    When the float is out you can scrape junk out with whatever works.
    Mind the water inlet opening into the tee that has the sight glass valve, it should be full open.

    The float goes back in so that it can flex up and down.
    The switch has an "up" label on it.

    Mark the wires well before removing them.
    JUGHNE Member Posts: 11,060
    Do you have a second probe type LWCO?
    Usually required on commercial buildings and must be manual reset.