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older pressure gauge

gibson
gibson Member Posts: 15
in THE MAIN WALL
I have a one-pipe steam system with an oil-fired Crown boiler. The pressuretrol is set to cut-in at .5 with a differential of 1. I've vented the system pretty well and it works fine.

But, the pressure gauge on the boiler doesn't seem right to me. The pressure gauge ranges from zero up to 30 psi, and reads 7 psi even when the boiler is cool. Do I have the wrong gauge? A broken gauge? Do I replace it? I'd like some advice. Thanks.

Comments

  • Steamhead (in transit)
    Steamhead (in transit) Member Posts: 6,688
    You either have a bad gauge

    or the pigtail under the gauge is plugged. Replace the bad part.

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  • gibson
    gibson Member Posts: 15
    gauge on boiler

    The Pressuretrol is mounted on a pigtail. But, the gauge I'm talking about is next to the Pressuretrol and is marked "Internal Syphon. It's just a dial. It has no pigtail and is mounted flush against the boiler.
  • Steamhead (in transit)
    Steamhead (in transit) Member Posts: 6,688
    Then it's the gauge

    replace it. Since you may not be able to find one with the internal syphon, get a new brass pigtail to mount it on.

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  • Dan_29
    Dan_29 Member Posts: 111


    Most steam boilers seem to come with 0-30 psi gauges. These gauges are virtually useless if you run .5 cut in and 1.5 psig cutout. The boiler pressure relief valve will blow at 15 psig. My brand new gauge (which came with the boiler) barely moves when the boiler runs.

    I bought a 0-5 psi gauge at the local supply house and installed it. It works properly by confirming my pressuretrol settings (cut-in and cut-out).

    Dan
  • bob young
    bob young Member Posts: 2,177
    code

    YOU should add a 30# additional gauge to comply to code.
  • Steamhead (in transit)
    Steamhead (in transit) Member Posts: 6,688
    Code requires the gauge

    to read twice the boiler's maximum allowable working pressure, which in the case of residential steamers is 15 PSI. Note that this requirement has NOTHING WHATEVER to do with the pressure requirements of the system that the boiler is connected to.

    The reason for this is, apparently there were boiler explosions in the old days where the gauge was indicating zero pressure. In these cases the boilers were so over-pressurized that the pointer on the gauge moved all the way around back to the zero mark. Having the gauge read twice the MAWP made this less likely.

    There's nothing wrong with having a 0-5 PSI gauge on a residential steamer to show the actual pressure, but the 0-30 PSI gauge must remain to satisfy Code.

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  • Dan_29
    Dan_29 Member Posts: 111
    gauge

    I neglected to mention that I did leave the 30 psi gauge on when I added the 5 psi gauge. However, I dropped the 30 psi gauge on the floor and it now reads 4psi even when the system is off. Yes, it is time for a new gauge (useful or not)as code requires it.

    Dan
  • William Faust
    William Faust Member Posts: 168
    Cool

    Watching that low pressure gauge hit the cut-out and cut-in pressures would inspire nostalgic visions of shifting to the tachometer on my college-era Triumph TR-4. Yeah, I gotta get a low pressure gauge. Plus comfy chair, pin-up posters, beers...
  • mtfallsmikey
    mtfallsmikey Member Posts: 765
    Looks like

    Too much pipe dope to me. Could have plugged the pigtail.
    Used to pull them and clean during annual cleaning.
  • Dan_29
    Dan_29 Member Posts: 111
    gauge

    Oh, for those carefree college days!

    Nowadays, when my wife notices that I am "playing around" with the boiler or watching the pressure gauge move, she suggests something "more useful" like taking out the trash or chopping ice off the driveway.

    Dan
  • Dan_29
    Dan_29 Member Posts: 111
    too much dope

    You are correct. I overdid the pipe dope. I was over-compensating for my previous use of leaky "street els" (as opposed to 90'regular elbows) which strip and leak even with pipe dope on them.

    In the end,I used only Tees (which did not strip or leak)and nipples to mount the gauges. As the pigtail is not plugged, I will clean this up after heating season when I add a vaporstat.

    Dan
  • Guest_5
    Guest_5 Member Posts: 35
    where

    can I buy such a low range gauge?

    I went to various home depots, lowes and even mom and pop shops. Can't seem to find any at Pex Supply either. I live in Brooklyn, NY area by the way.
  • bob young
    bob young Member Posts: 2,177
    bklyn suppliers

    try H. & L. Supply on coney island ave bet. ave H & foster or davis & warshaw could order for you if not in stock. branch also on c.i. ave & ave I
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