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Too much pressure/clogged pigtail?

Long time lurker, first time poster.

I'm the new homeowner of a 1-pipe steam system in Western MA. My boiler is a Dunkirk psb-5d (, approx 25 years old (per previous homeowner).

My problem is as follows: Water is exiting the system, such that in very cold weather periods as we've been having, I need to add water every 4-5 days or so, else the auto-feed comes on. Main and radiator vents are spitting out steam after they should've shut tight, i.e., after the dry air's been expelled from the system.

I've replace several of the rad vents with the appropriately sized maid-o-mist or gorton vents, to the best of my ability, though some retain the adjustable vents the previous homeowner installed just prior to my purchase. I replaced the clogged-to-death Hoffman main vents on the 2 tapped mains last year with Maid-o-Mist #1's. On one of the two main vents the housing has cracked, from what I'm assuming is excess pressure while the float bravely held, while the float on the other has on the other had failed, meaning that steam blows out of that one.

At first I thought maybe I've got a crack in the boiler itself, which I have yet to test by flooding the boiler and looking for puddles. But, I'm more inclined to think, and asking you guys for your input on whether there's too much pressure in the system. That is, am I burning gas to heat water that's already been heated enough to create enough psis/steam to heat my house, and I'm therefore burning gas & creating excess pressure, leading to waste and busted vents?

So if this is pressure, time to troubleshoot the pressuretrol. My boilder has one of those 30 psi gauges, which I know is useless other than for meeting code, so that's not telling me much. Per the picture, I've got a Honeywell pressuretrol mounted onto the boiler jacket, with the pigtail coming off the sight-glass. Most folks I see on here have their pigtail dangling in the air, easily accessible/removable. Pic: I think I need to remove the pressuretrol and pigtail and clean or replace the pigtail so that the pressuretrol registers the correct pressure within the system and cycles off accordingly, but the pigtail is mounted in such a way that simply twisting it off isn't as straightforward as if it were mounted perpendicular from the boiler.

Let me know your thoughts, what I'm missing or tell me I'm way off. Thanks.


  • acab1975acab1975 Posts: 9Member
    image of near-boiler piping:
  • BobCBobC Posts: 4,941Member
    The pressuretrol should be removed every year or two and that pigtail cleaned to make sure it's clear. If the pigtail gunks up the pressuretrol can't do it's job. Take the cover off that pressuretrol and make sure the white dial is set as low as it can go.

    That boiler is badly piped, a side outlet boiler should use both outlets to feed the header, that style of boiler is very sensitive to the near boiler piping. If you look at the boiler manual you will find the suggested piping.

    It looks like you have two steam mains, each should be tied into the boiler header separately, feeding them with a bullheaded T is not good.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • acab1975acab1975 Posts: 9Member
    Using only one of the side outlets vs both was a bonehead move on the installer's part (who installed it 20 yrs prior to my purchasing the home), yes?

    I'll drive down the dial on the pressuretrol ASAP. Thanks.

    Seeing as how closely mounted the pigtail is to the jacket, it'll be a female dog to remove, I'm thinking...any tips?
  • BobCBobC Posts: 4,941Member
    You might be able to swing that pressuretrol because the boiler jacket will deflect a bit, just make sure you use a wrench on the brass base - don't try to use the case to twist it off till you have broken the pipes hold.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • marcusjhmarcusjh Posts: 76Member
    Had to clean the pig tail last year (I think it was last year...) - it was a pain to take everything apart, but needed to be done because the pressure was going way up. I was all set to go to the local plumbing supply house and pay for one, when I caught a post here that mentioned submersing in Baking Soda & Warm Vinegar.

    POOF. It was like magic. The pan turned black, and after agitating a bit, the pigtail was clean as a whistle. Saved me a trip to the supply house :)

    My only issue was trying to figure out how to prime the darn thing with water. Had it all mounted, and ready to go, and there I was, trying like crazy to figure out how to get water into it -making funnels with cardboard, tin-foil, paper... then it hit me -Should have run some water into it before mounting it. Duh. Oh well, I'm learning :smiley:
  • FredFred Posts: 7,776Member
    It's good to prime the pigtail but not critical if you forget to. That pigtail has air in it and that air will act as a buffer for the Pressuretrol and after a couple heating cycles, condensate will build up in the pigtail loop.
    @acab1975 , if you can swing that pigtail a little, with a small pipe wrench, it will likely give you enough room to turn the Pressuretrol. You may want to put a coupling on the pigtail and add a nipple to it to bring the Pressuretrol up, above the top of the boiler for future ease of access or, depending where your pressure gauge is, move it to that tapping and put a Tee on the pigtail so both the Pressuretrol and gauge can mount to it.
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