Boiler feed float sticking

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  • This topic has 2 replies, 3 voices, and was last updated 16 years ago by cove3.
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    • #277693

      The McDonnell & Miller Model 47 boiler feed float on my steam boiler doesn’t always stop the water input. It seems to stick but when I push on the lever mechanism it works for a while. I drain it periodically to clean out the rust & sprayed wd40 on the external pivot points.

      Is there anything else I can try? Does the float go bad on these after 15-20 years? If I replace the unit, do I try & disassemble & replace the float, or just the black ball unit, or the whole assembly including the cut off & the square thing below the cut off?

      Thanks in advance


    • #296914
      Retired plbg1
      Try this ite they have your parts, maybe you just need new washer inside, let me know.

      Art retired plbg

    • #296915

      Success. I figured out why the boiler feed cut off float wouldn’t stop the flow of water to the boiler. I found that the cast iron float bowl was full of sludge/rust which was reducing boyancy and jamming the lever from closing the valve.

      Unfortunately I found this out after buying a new McDonnell 47-2 unit at $470, installing it, and then taking apart the old unit.

      All I had to have done with the old unit is unscrew the 4 bolts at the bottom where the weekly drain of water comes out and it would have allowed me enough of a look to have seen the sludge which I could have scraped out with a screwdriver and flushed out.

      In the process, I discovered that there’s a screen that needs to be cleaned yearly, which my boiler service people never did. It was full of crud also. I also found out that the new 47-2 unit has a design change from my old one so that the screen and the shut off valve are both removable from the bottom of the unit.

      I would think that since most people don’t properly flush out the float unit weekly as recommended, that this would be a common problem with steam boilers. Hope my experience saves others a service call and purchase of a new unit. Done correctly, it would be at most a 1 hour job to clean both the float chamber and the screen.

      Regards, Ron

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