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both Hoffman 75 vents stuck open

Single pipe steam system
2 yo hoffman 75 on the dry return started spitting black water and steam Jan 1 or thereabouts. Put a bucket under it set a reminder to top off the water every week until the HVAC appt Jan 25th.
Jan 21 noticed the 2nd hoffman 75 that is at about 70' point on the main was also stuck open and vents steam continuously. That is less than 1 yo.
Having to add water about every 48 hours.
HVAc appointment postponed- Jan gas bill doubled!
How do I get these off to swap them or clean them myself? I can't wait for HVAC to show up. I tried my largest pipe wrench and they didn't move- how aggressive can I be?

and yes I know we need to clean the sludge out of the system- it was on the list but didn't get done before the heating season started. I do blowdowns every few weeks at least.





1 pipe steam system, 2014? Weil-McLain EG-75-PDIM S5, 2 Hoffman75 vents on main

Comments

  • JUGHNE
    JUGHNE Member Posts: 11,042
    I think you have other problems that the vents did not cause.

    What pressure shows on the gauge and where is the control set at to shut down?
    Has the pigtail been cleaned recently?
  • Jamie Hall
    Jamie Hall Member Posts: 23,165
    A hoffman 75 which hasn't been abused can last 90 years -- I know, because I have one. However... high pressure can lock them closed, or damage them (or for that matter any vent) so much that they will never close again. If you have any reason to suppose they may have been overpressured -- anything over 3 psi -- try tapping them firmly but gently. That sometimes unlocks them.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    jennlmorrow1
  • cross_skier
    cross_skier Member Posts: 201
    The old green ones are said to be better than the new unpainted ones.  My neighbor saved two 75's by boiling in 50-50 mix of vinegar and water for 30 minutes, she may have been lucky
    jennlmorrow1
  • JUGHNE
    JUGHNE Member Posts: 11,042
    JUGHNE said:

    I think you have other problems that the vents did not cause.

    What pressure shows on the gauge and where is the control set at to shut down?
    Has the pigtail been cleaned recently?

    jennlmorrow1
  • jennlmorrow1
    jennlmorrow1 Member Posts: 9
    JUGHNE said:

    JUGHNE said:

    I think you have other problems that the vents did not cause.

    What pressure shows on the gauge and where is the control set at to shut down?
    Has the pigtail been cleaned recently?

    Agreed, pigtail has not been cleaned in the 2 years we've owned it (and not before that if I were to guess)
    The gauge is usually not reading any pressure although I did catch it reading 4psi on the night I heard the second vent venting steam.

    A hoffman 75 which hasn't been abused can last 90 years -- I know, because I have one. However... high pressure can lock them closed, or damage them (or for that matter any vent) so much that they will never close again. If you have any reason to suppose they may have been overpressured -- anything over 3 psi -- try tapping them firmly but gently. That sometimes unlocks them.

    I tapped them both last night- the newer one seems to be functioning again! thanks!


    1 pipe steam system, 2014? Weil-McLain EG-75-PDIM S5, 2 Hoffman75 vents on main
  • JUGHNE
    JUGHNE Member Posts: 11,042
    Back up and show both the gauge and the entire control above it, thanks.
  • jennlmorrow1
    jennlmorrow1 Member Posts: 9
    JUGHNE said:

    Back up and show both the gauge and the entire control above it, thanks.

    I assume you're confirming the pressuretrol setting so I'm including close up of that


    1 pipe steam system, 2014? Weil-McLain EG-75-PDIM S5, 2 Hoffman75 vents on main
  • JUGHNE
    JUGHNE Member Posts: 11,042
    The screw on top can lower that indicator down for lower pressure.
    You can go down slowly until it feels like it is going fall apart, then a turn back up.

    Your pigtail probably needs cleaning, this can affect your pressure by fooling the control as the steam may be trying to push sludge thru the ptail.
    If your gauge showed 4 PSI with the present adjustment. (and those gauges are not at all accurate) you may be running very high pressure that would push that water up and out......eventually wrecking the air vents in the basement and on your radiators.
    jennlmorrow1
  • JUGHNE
    JUGHNE Member Posts: 11,042
    edited January 2022
    You can probably clean your pigtail your self.
    Post pictures from farther back if any questions.

    Also take off the cover and set the white wheel to 1.
    jennlmorrow1