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ALL radiator vents hissing/spitting, building over heating

chuckadoo Member Posts: 28
New install, ran well for a few weeks, but last night building is OVER heating and ALL radiator vents are hissing for entire cycle (never closing). No hissing at the end of main vents, though. Most rad vents are Hoffman no. 40’s, (6psi operating pressure). Honeywell Pressuretrol cut in was set to 2 with internal diff set to 1 added (watching the 30 psi gauge it actually read 2 cut in, 6 out. Honeywell pressuretrols not very accurate?). Is this a classic case of “dirty” water?  I did not have time to test cleanliness of water but the upper portion of glass gauge did look dry. Water level in glass gauge was very stable.  

this was all the information I was able to gather for the time I had here. I plan to return tomorrow, any suggestions as to what the problem is or what to look for would be much appreciated.

also, I turned down Honeywell control to 1/2 psi cut in with 1 diff (which came out to be 1 cut in and 5 out on gauge). I turned down thermostat. No more over heat calls but ALL radiators still hiss/spit for the entire cycle, only quieting when I shut off boiler and gauge hit zero. 

If it is dirty water, could the building overheat? And, at the same time not get the 180 degrees to close air vents?

If the boiler was overpressured at some point (above ten psi) would ALL radiator vents fail?


  • mattmia2
    mattmia2 Member Posts: 3,999
    Is the pigtail or whatever is used to connect to the pressuretrol from the boiler clear? Is there some sort of water seal to keep steam out of the pressuretrol? Possibly some sort of issue with the linkage in the pressuretrol.

    Seems like the boiler is probably oversized if it is reaching that pressure, but it should still work if the pressuretrol is working and wired correctly.

    Is there only one pressuretrol or is there a secondary safety pressuretrol? Are you sure it isn't a lwco or some other control shutting the boiler down?
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,511
    The cheap pressuretrols which come with the boiler are notorious for being inaccurate, and disconnecting their linkage when adjusting the settings down.
    there is a procedure described here somewhere for fixing them, but vaporstats are best with an accurate low pressure gauge.—NBC 
  • chuckadoo
    chuckadoo Member Posts: 28
    I connected a voltmeter to Honeywell pressuretrol, and watched its cycle, it is working correctly, just inaccurately. There is a manual high limit presuretrol, I’ll check the pigtail today. Any advice on air vents?
  • neilc
    neilc Member Posts: 1,474
    if the Hoffmans are rated to 6, and you're seeing 6 regular, and asked about 10,
    yeah, they may all be bad, or, are they so wet steam can't reach them ?
    gotta manage that pressure, set the Ptrol to its bottom, without disconnecting the linkage, and provable repeatable restarts.
    how was the pigtail?
    what is the manual reset set to ?

    how new is the install? and has it been skimmed? how many times?
    you mention the water line is stable, but the top of the sightglass is dirty,
    you could be throwing wet steam up thru, skim.
    how does the water look in the glass? dirty?

    and of course, pictures,
    sightglass, Ptrols, how's the header?

    lastly, (its warm here in Ct),
    what's controlling the boiler for OA temp,
  • chuckadoo
    chuckadoo Member Posts: 28
    I’m leery to post pics as this is not my install, and there are no dangers present. I’d hate to void installation warrantees. I am not paid for any troubleshooting, I just do it for self education, and simply that I enjoy it! These opportunities don’t come around too often so I try to learn as much as I can- long spiel for no pics! So, any replies and teachings are much appreciated!

    I tried the Lobbestael method of checking water quality. I closed valve at bottom of glass, with 1 and 1/2 psi in boiler, opened peacock, glass drained with about 2 seconds worth of water spurting from top of glass. Then a steady “drip” of water and steam spewing from petcock, continuing indefinitely, while glass looked dry. Again, sorry for no video or pics. Does this describe dirty water?

    I also took a sample of water from bottom of sight glass to boil test. But, then thought later that I may have needed water from top layer, where installation oils collect? Does taking a sample from below the water line suffice? I have just returned home and have not boiled yet. Water sample:

    There was no pig tail on pa404a pressurtrol.
    What did you mean by vent being “so wet steam could not reach them”? The vents that are spitting? I assume radiators that were spitting may just be pitched the wrong way. I temp tested a nonspitting vent that never stops hissing

    I could not find a known good vent to “throw parts at it and see if it works” replacement.

    install, a few weeks old. Uncertain about what skimming has been done. There is an OA control, I did not get is make and model. Manual reset 8psi.
  • mattmia2
    mattmia2 Member Posts: 3,999
    Is there any trap between the boiler and the pressuretrol? it could be a pigtail or it could be a set of fittings arranged to make a water seal. you are asking what is wrong but don't want to show us what is wrong. If there is no water seal then the diaphragm in the pressuretrol could have been damaged by the steam. If that is the case, you will have to get a water seal on both pressuretrols and test the safety control for proper operation. Not a bad idea to replace the pressuretrol with a vaporstat if it has been damaged by improper installation..
  • chuckadoo
    chuckadoo Member Posts: 28
    There is straight piping to pressuretrol, no fitting u seals of any kind. Pressuretrol does work, just not very accurate. High limit does have pigtail.
  • chuckadoo
    chuckadoo Member Posts: 28
    Definitely more surface bubbles, but not foaming out the top. Good?

  • neilc
    neilc Member Posts: 1,474
    well, yeah, but, pictures are worth lots of words(that I don't have to type)

    I consider your water dirty = cloudy(red) = chemically treated, and would skim(X's n) and dump the rest and run clear water like the second beaker,

    the vents should close, unless they're damaged or also dirtied and need cleaning

    from what I can see your not protecting the Ptrol, and you should,

    just curious?
    how do you come by this boiler and operation to learn from?
    whose is it? landlord, neighbor, your apartment is upstairs ?
  • chuckadoo
    chuckadoo Member Posts: 28
    I’ve done work for an investment group (basically, a group of people that own ALOT of buildings) from their start. Mostly plumbing. They are just being nice and letting me look before repairs are made.  
  • Schreyer
    Schreyer Member Posts: 1
    Had a similar problem after my boiler was replaced years ago. Reputable installer could not fix it and walked away. Finally an old timer told me to put diatomaceous earth in system to remove cutting oil. It worked.
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,511
    Diatomaceous earth, AKA Squick just moves the oil from water surface to boiler bottom, hiding the problem.
    A real skim is best.—NBC
  • dopey27177
    dopey27177 Member Posts: 759
    The Hoffman 40 vent valve can be used up to 10 PSI. It has a drop away pressure of 6 PSI, that means the vent valve will not open until the steam pressure drops to 4 psi or less.

    If I read you right your boiler cuts in at 2 psi and cuts out at 6 psi.

    You proper setting at max pressure should be cutout at 2 psi and cut in at 1 psi.

    Most 1 pipe steam systems will work well at .5 psi cut in and 1 psi cut out. for that you will need a vapor stat.
    Recall your installer and have him do the install and install a secondary pressure gauge. 30 inch vacuum 15psig
    with a 31/2" face. Much easier to read.