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0-3 gauge and negative PSI

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  • Captain Who
    Captain Who Member Posts: 508

    Those are 30 in. H2O gauges. That's 1.08 psi. Wouldn't work for my system which sometimes hits a hair over 2.0 psi at cutout, even though before it was cutting out at 1.5 psi.

  • JaymeHart
    JaymeHart Member Posts: 56

    oh this one is interesting:

    https://www.ebay.com/itm/203647430668

  • ChrisJ
    ChrisJ Member Posts: 17,141
    https://forum.heatinghelp.com/discussion/comment/1883352#Comment_1883352

    You might have already said and I missed it but what main vents do you have?

    My system holds much less vacuum since switching to Gorton vents. I think their design tends to open easier.

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

  • Jamie Hall
    Jamie Hall Member Posts: 26,968

    Folks, I have a cheap 0 to 3 psig gauge on Cedric. And have for years. It's fine.

    Now… there are several considerations which may contribute to that. First, system pressure never goes above 7 ounces gauge. Second, the gauge — and vaporustat — are mounted on the drop header rather than on the boiler — a configuration I very highly recommend (much more stable pressure when firing). Third, the system in question is a Hoffman Equipped vapour system. Among other bits of trivia for such critters, assuming the system is working properly, the main vents never, ever close, so the dry return pressure is always atmospheric — zero gauge. Why is this significant? If there is even one trap somewhere which is open for condensate (and there will be) a vacuum will not develop in the steam mains — it will just pull through from the dry return.

    Now when the system was originally installed, in 193, the only vent was a Hoffman 76, which is a vacuum vent. Under that condition, quite a significant vacuum could — and very likely did — develop (I wasn't operataing the system at that time). Still limited by the Differential Loop to a maximum of 8 ounces differential, though. When I took over the system a couple of decades ago, the 76 had been replaced with a 75 — and being a novice at the time, I swallowed the "more venting more venting" idea and added the Gorton #2. Sort of wish I'd known better and put on two 76s, but… they aren't cheap, and I am.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • JaymeHart
    JaymeHart Member Posts: 56
    edited January 22

    ok. LAST question for now:

    Does adding a longer 1/4" pipe between the pigtail and Vaporstat & gauge help with reducing the "bouncing" of the preassure reading?

    I see (Jamie Hall, thanks again for all your help and knowledge!) that you installed the Vaporstat and pressure guage on the header, because that improved the measurement stability. My header is unfortunaly not tapped for that, and I'm not gonna DIY that. ;)

  • ChrisJ
    ChrisJ Member Posts: 17,141
    https://forum.heatinghelp.com/discussion/comment/1883423#Comment_1883423

    No,

    But a snubber or a partially closed valve will.


    Curious why you have so much bouncing with a 3 psi gauge on a pigtail? The pigtail buffers it some, and a 3 psi gauge shouldn't really be moving much on a steam boiler. Is your water clean?

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

    ethicalpaul
  • JaymeHart
    JaymeHart Member Posts: 56

    Yes, water is clean. It is a new boiler. It is not bouncing a lot, just a few oz. I am not concerned about it...not worth a snubber. just wondered if a longer pipe might help.

  • Jamie Hall
    Jamie Hall Member Posts: 26,968

    How much, if at all, a pressure gauge (or vapourstat, by the way) will bounce around really has nothing to do with surging , but it does have to do with exactly which tapping it is connected to, and how, and the internal geometry of the boiler. Some on boiler locations may be quite stable. Some… not so much. It's not a problem if one is working in the pound or so range. It can be if one is working in the ounces range dues to false trips on the vapourstat.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • ethicalpaul
    ethicalpaul Member Posts: 8,313
    edited January 22

    Oh it can definitely have to do with surging too

    Basically, if the sloshing water gets to the level of your pressure gauge pipe's tapping, you may see gauge activity from the boiling action of the water.

    This can be from heavy boiling action from bad water, or it can be from a higher than specified water level like I run. (I see all kinds of weird stuff with the different experiments I run my boiler through)

    Jamie will never see that because his water is good and his gauge tapping is in his header.

    But it's usually not a big deal—you'll still get a good pressure average

    The longer pipe might help or it might not if the sloshing water is getting sloshed against the tapping where your long 1/4" pipe is

    NJ Steam Homeowner.
    Free NJ and remote steam advice: https://heatinghelp.com/find-a-contractor/detail/new-jersey-steam-help/
    See my sight glass boiler videos: https://bit.ly/3sZW1el

  • JaymeHart
    JaymeHart Member Posts: 56

    There is a side tap a couple inches above the water line, where the existing pigtail comes out, and the Vaporstat and 0-3psi gauge sit. And there is a tap on top, no pigtail, with a 0-30psi internal siphon gauge.

    If the top might be better for stability, I could always switch it and add the pigtail stack to the top.

    I would keep the 0-30 guage for safety and insurance, as well.

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