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Pressure Gauge in the Boiler Frame?

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Hi guys! What exactly is this gauge embedded in the top of the boiler frame? 
When the system is heating up it pressure pushes to 12 psi and once the house is heated the pressuretrol cuts out it seems to settle at about 8psi. 

Comments

  • justdonlon
    justdonlon Member Posts: 12
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    From all I’ve read the steam pressure should be low like .05 to 2 psi. I haven’t come across any notes about an internal syphon pressure gauge and what a normal range is
  • justdonlon
    justdonlon Member Posts: 12
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    Actually I found this thread and a few similar ones which suggest not to bother too much with the internal siphon pressure reading.  



  • neilc
    neilc Member Posts: 2,703
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    does that gage go back down to zero, 0, when the boiler is off for a bit ?

    post a more general, distant picture, showing the entire boiler, and the pipes above it to the ceiling,

    and post a picture of the Ptrol, and its pigtail, (the looped pipe under or behind the Ptrol),
    what is it set to?
    known to beat dead horses
  • bburd
    bburd Member Posts: 917
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    “Internal syphon” simply means the gauge does not need a separate pigtail to protect it from steam.

    The gauge is probably defective, but since you don’t want more than 2 psig in a residential steam heating system the pressure range you are seeing suggests that your pressuretrol is set too high or its pigtail is clogged.  Excessive steam pressure may have unfortunate effects throughout your system.

    Bburd
  • Jamie Hall
    Jamie Hall Member Posts: 23,313
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    Since this is posted under strictly steam, I have to assume that this is, in fact, steam -- in which case the pressures shown on that gauge are simply absurd. On the other hand, if it is hot water, they are a bit low but not hopelessly so.

    Clarify?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • mattmia2
    mattmia2 Member Posts: 9,660
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    It is easy to bend the case of that type of gauge a bit and make it wildly inaccurate.
  • justdonlon
    justdonlon Member Posts: 12
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    fehere are a few more pics as requested. Yes it’s steam. Yes the gauge goes back down to zero after it cools down. 
  • justdonlon
    justdonlon Member Posts: 12
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    And the pipes to the ceiling 
  • neilc
    neilc Member Posts: 2,703
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    I will suggest your pigtail is clogged, and the Ptrol is not controlling the pressure to which it is set,
    I see the red bucket, do you do a weekly blowdown on your low water cutoff ?

    to check and clear the pigtail,
    turn off the boiler, then lower the water level to the bottom of your sightglass,
    unwire the Ptrol, and detach it from the pigtail, use 2 wrenches, one on or thru the pigtail, and the other on the flats under the Ptrol,
    with the Ptrol detached, blow down thru the pigtail, yes, your lips,
    if it is free there would be some slight initial resistance as you clear water in the loop, then it should be free breathing back into the LWCO, and boiler,
    if it is not clear then further detach pigtail from LWCO and poke it from both ends to free gunk within,
    a length of electrician's fish tape, or the outer jacket to lawn mower throttle cable, can make good pigtail snakes,
    make sure there's no buildup or clog where pigtail threads into LWCO, "freebreathing", and check the bottom of the Ptrol for gunk, there shold be a small hole visible and clear into the Ptrol bellow, carfeful poking there,
    upon reassembly, prime ~ 1/4 cup of water back into pigtail, rewire Ptrol, refill to usual water line, and restart boiler,
    settings on Ptrol look correct, you should be cutting in around 0.5, and cutting out ~1.5 psi,
    known to beat dead horses
  • neilc
    neilc Member Posts: 2,703
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    and can we see the same wide picture of boiler and pipes from the other side,
    and another showing that red tank, and those pipes at the floor to top of boiler,
    known to beat dead horses
  • justdonlon
    justdonlon Member Posts: 12
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  • justdonlon
    justdonlon Member Posts: 12
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    Thanks for the detailed instructions @neilc .
    I followed the instructions - blew through the ptrol pigtail - it was nice and clear into the LWCO. (I had cleared out the pigtail previously).

    I refilled the water and fired it up.
    It took about 20 -25 min to heat up the house - the siphon gauge rose to about 12 psi, and then
    the pressuretrol cut out and stayed off. The siphon gauge settled to about 8psi.
    My suspicion is that the siphon gauge is just wrong/faulty.
  • justdonlon
    justdonlon Member Posts: 12
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    and yes - the bucket is there for the weekly blowdown of the LWCO
  • neilc
    neilc Member Posts: 2,703
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    now me thinks you need a new Ptrol,

    when you blew the pigtail, any chance was the drain on the LWCO open ?
    .
    if you remove a wire off the Ptrol, any chance that boiler fires ?
    (with no call for heat on the hot water loops either)

    I have never seen offset sightglass valves like those before,
    most valve stems are in line with the port or pipe to the boiler, and make for easy cleaning and minimal disassembly there,
    your glass ports would be a bit more involved to check and clean,
    known to beat dead horses
    mattmia2
  • justdonlon
    justdonlon Member Posts: 12
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    No - the LWCO was closed when I blew the pigtail.

    When you say the glass ports/sightglass valves are you talking about the siphon gauge in the actual blue frame/cabinet?
  • neilc
    neilc Member Posts: 2,703
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    the sightglass is between the 2 brass valves I referenced, the glass tube showing your water level
    known to beat dead horses
  • neilc
    neilc Member Posts: 2,703
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    i guess it's possible,
    but for a gage that returns to 0, I'ld be surprised that it reads so far over what the Ptrol is set to,
    under, or no movement , yes,
    but wildly over, and I'm thinking the pressure is high,
    I guess internal springs cold be weak,
    hold on, i'll be back with a water gage,
    known to beat dead horses
  • neilc
    neilc Member Posts: 2,703
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    I have clear(was) vinyl tube, on a hose end repair, attached to the boiler drain,
    the tube is long enough to reach up over pipe at the ceiling, and back down to about 6 inches to the floor for safety, this end stays open to atmosphere,
    tape the open end to the length with the hose end to avoid hose shifting later,
    I don't leave the drain open when I'm not there,
    this will measure inches of water above normal water line real well.
    for every 28 inches the water line in the clear tube climbs above the boiler water line, you have 1 psi pressure,
    attach to the boiler drain while boiler is off and other gage reads 0,
    open the drain and the water line in the tubing should match the boiler water level, mark the tube with tape or a marker,
    start the boiler and watch the water rise in the tubing,
    shut the boiler off before the water line gets too high and floods over,
    if the Ptrol cuts out, and the water line is only 56(2psi) ~ 65 inches above normal boiler line,
    then you know the 0-30 in the boiler case is bad,
    if water in tube looks like it's going to the ceiling, and over, then the pressure is real, and the Ptrol, or the path to the boiler is bad,
    known to beat dead horses
    MikeAmann
  • mattmia2
    mattmia2 Member Posts: 9,660
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    If the bordoun tube in the gauge gets bent it is really easy for them to behave incorrectly. The needle has a little gear and rack that amplifies tiny movements of the tube in to needle movement.
  • 109A_5
    109A_5 Member Posts: 1,385
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    Hello @justdonlon,
    neilc said:

    I have never seen offset sight glass valves like those before

    @neilc, My Boiler has those same sight glass valves along with the McDonnell & Miller 67, mine is probably 53 years old. Harder to clean out.

    @justdonlon With the pressuretrol off the pigtail you probably should be able to see the Stainless Steel diaphragm (silver color) through the 1/4 NPT fitting's orifice.

    With the pressuretrol settings at minimum I can blow into the 1/4 NPT fitting and hear the micro-switch click. Maybe your micro-switch has failed closed or the calibration is just that bad.

    I've had my pressure gauge apart, it has an Internal Syphon tube, however if my gauge was mounted like that gauge in the OP's Boiler the Internal Syphon may have little affect protecting the gauge. It would be like the pigtail on the pressuretrol is laid flat and horizontal instead of vertical. Maybe the Bourdon tube just fills up with condensate and it is OK.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • mattmia2
    mattmia2 Member Posts: 9,660
    edited November 2022
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    109A_5 said:


    I've had my pressure gauge apart, it has an Internal Syphon tube, however if my gauge was mounted like that gauge in the OP's Boiler the Internal Syphon may have little affect protecting the gauge. It would be like the pigtail on the pressuretrol is laid flat and horizontal instead of vertical. Maybe the Bourdon tube just fills up with condensate and it is OK.

    Or it got bent when someone was removing or installing the top panel of the jacket.

    Take an old bourdon tube gauge that is trash and clamp the fitting in a vise and twist the case around. it will read all sorts of things.

  • justdonlon
    justdonlon Member Posts: 12
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    Thanks for the input all.

    Here's what I know:
    The pressuretrol does cut in and out - but I don't know if it's cutting in and at the desired pressure.

    The way I see it I have 4 options:
    1. Do nothing and assume the pressuretrol is good and the syphon gauge is bad - live with the uncertainty
    2. Proactively replace the pressuretrol (without proof that the pressuretrol is bad) - pay high $$
    3. Add a low-pressure gauge to the same pigtail as the pressuretrol - lower $$ but work
    4. Replace the internal siphon gauge - is this even possible?

    Any other options?
    What would you do?
  • mattmia2
    mattmia2 Member Posts: 9,660
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    3 or 4. 4 probably involves removing the top of the jacket of the boiler. 3 involves a gauge, tee, nipple, and teflon tape
  • 109A_5
    109A_5 Member Posts: 1,385
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    Hello @justdonlon,
    I would build a Manometer (easy and inexpensive to do) connect it to the drain spigot and determine the actual Boiler pressure. Or just prove that the pressure it is seriously too high (water line + 55 inches). Difference in Boiler water line to the water height in the Manometer tube. Then you will know what is reading and / or operating correctly.
    1 PSI = 27.6799 inches of water column.
    So for example 12 psi = 332 inches or about almost 28 feet.
    Way too much return water height for the typical "A" dimension of a residential steam system. Crazy, you may have to stop the test early by closing the drain valve. The Boiler gauge is probably wrong. I would not build a 28 foot Manometer, however you can extend the clear tubing vertically with a garden hose and go up the basement stairs to extend the height a bit.

    Nothing wrong with more than one gauge. Code says you must have a 0 - 30 PSI, but you can add other gauges if you want. If your 0 - 30 PSI is not correct and you decide to replace it (most work) I would probably would raise it up out of the Boiler jacket so it is more serviceable in the future. Some folks like adding a low pressure gauge too, but their system is not going up to 12 psi. I would get the system under control before adding a low pressure gauge, you may damage it. My system is usually under 1 inch of water column. You may be able to re-calibrate the Pressuretrol, if it works correctly and is just out of calibration.
    Also see;
    https://forum.heatinghelp.com/discussion/comment/1717664#Comment_1717664
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • justdonlon
    justdonlon Member Posts: 12
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    Ok really newbie question - which is the drain spigot? is it this?

  • mattmia2
    mattmia2 Member Posts: 9,660
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    What you circled is the valve to blow down the low water cutout. The drain for the boiler is probably that boiler drain on the other side that is extended over the burner.
  • 109A_5
    109A_5 Member Posts: 1,385
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    Hello @justdonlon,

    If you are going to go with the Manometer for testing. Clear tubing and a fitting like this
    https://www.supplyhouse.com/Jones-Stephens-G20137-5-8-Hose-Barb-x-3-4-Female-Hose-Brass-Garden-Hose-Swivel-Lead-Free?_br_psugg_q=garden+hose+fittings

    The drains on your boiler I would use (see picture), either would probably work fine.







    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • JUGHNE
    JUGHNE Member Posts: 11,062
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    IMO, the simplest thing to do is remove the pigtail/control.
    You may have to swivel the pigtail to get the control removed.

    Then I would add a 6" brass nipple and coupling to the top of the LWCO.
    Then install the pigtail on that with a brass tee.

    Add a 4" nipple and 90 for a low pressure gauge, 0-5 PSI.
    You could put a 1/4" ball valve for isolation, just open to read pressure.

    Then you can see what the pressure control is feeling.

    The added 6" nipple gets the pigtail up out of the boiler water and may keep it cleaner longer.

    You could put a 1/4" union where the coupling is, that would let you get things apart easier in the future.
    mattmia2
  • justdonlon
    justdonlon Member Posts: 12
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    Thanks All! This is a good project to tackle over the weekend.