both Hoffman 75 vents stuck open

jennlmorrow1

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.

JUGHNE

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

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.

cross_skier

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

JUGHNE

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

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.

Jamie Hall said:

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!

JUGHNE

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

jennlmorrow1

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

JUGHNE

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.

JUGHNE

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.