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Mystery: Main vent air eliminator keeps breaking

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edg2103
edg2103 Member Posts: 12
edited January 2022 in Strictly Steam
I have a one-pipe steam heating system set to 1.5PSI. I bought the house last year, and the system had been leaking from a corroded main. Recently, I had a plumber switch out the rusted pipes. When he turned on the system, we noticed an 3/4"x1/2" air eliminator on a 1-1/2" main was busted (looked cracked). I replaced it with another one with a Home Depot air vent, but that one was stuck on the open position within a couple of days. Replaced it again, with a Gorton #1 air eliminator, but that one only lasted a couple of days as well.

Anyone know what the issue could be? The image of the eliminator and nearby pipes is below.

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  • edg2103
    edg2103 Member Posts: 12
    edited January 2022
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    One thing I noticed is that the nipple seems a little long, online I've seen 6" nipples recommended. Could this cause the vent to be damaged?

    Or could it be the vent is not well pitched or poorly located? In the pic above, you can see that the slope from the tee to the elbow is downard instead of upward. Could that be causing water hammer if condensate gets stuck in that elbow? And could that water hammer break the vent?
  • Jamie Hall
    Jamie Hall Member Posts: 23,313
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    Are you quite sure that your system is shutting off at 1.5 psi? One reason why vents die is if they get overpressured. They aren't meant to work at more than 3 psi.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    edg2103ethicalpaul
  • edg2103
    edg2103 Member Posts: 12
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    Thanks Jamie. Are you suggesting the pressuretrol may broken? It clearly indicates ~1.5 PSI on the pressuretrol, see below...

    How can I check if it's working properly?
  • delcrossv
    delcrossv Member Posts: 742
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    edg2103 said:

    Thanks Jamie. Are you suggesting the pressuretrol may broken? It clearly indicates ~1.5 PSI on the pressuretrol, see below...

    How can I check if it's working properly?\

    Those pressuretrol scales are notoriously inaccurate. I'd suggest installing a low pressure gauge (0-3psi) in parallel with your 0-30 psi "code" gauge.

    There's no issue with a long nipple for a mains vent. Do the failed vents spit water?
    Trying to squeeze the best out of a Weil-McLain JB-5 running a 1912 1 pipe system.
    edg2103
  • edg2103
    edg2103 Member Posts: 12
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    @delcrossv, the vent doesn't spit water, just moist steam (which of course, condenses into water). Will look into a low pressure gauge, thanks!
    delcrossv
  • Jamie Hall
    Jamie Hall Member Posts: 23,313
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    How long has it been since the pigtail connecting the pressuretrol to the boiler was removed and cleaned?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    delcrossvGordoedg2103
  • dabrakeman
    dabrakeman Member Posts: 552
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    I can't see your picture very clearly but if you can see a low spot where condensate could collect without a route back to the boiler, it probably is.  Have you heard hammer from that area?
    edg2103
  • jhewings
    jhewings Member Posts: 139
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    If your pressuretrol is accurate, your cut-in is 1.5. What is your differential? The differential determines your cut-out. You have to remove the cover to check this. If your pressuretrol is working perfectly but the differential is say 3, then pressure can get to 4.5.
    edg2103
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,532
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    @edg2103

    If it's piped like I think it is it could be part of the problem.

    The vent is dead ended at the end of the main.

    It looks like that tee is laying on it's side looks like it's tied into that 1 1/4" copper drip that comes off the side of that tee.

    That means that main is 1/4 full of water
    edg2103