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Replacing a pressure gauge - need some advice

Jshine Member Posts: 19
I'm a homeowner - I have a 1-pipe steam system - gas furnace.  The current pressure gauge is a U.S. Gauge that has 2 scales - 0-30 psi and 0-200 kpa.  I have the system adjusted to .5 > 1.5 psi (as best as i can read the gauge).  The thing is the gauge 'hangs" randomly - and it frees up if I give it a tap or 2.  Since I'm only interested in monitoring the first few marks in the psi scale - I'm thinking of replacing the current gauge with something that has a lower psi max (maybe 10 or 5).  2 questions.

1 - Is this a fairly simple job - just unscrew the old and screw on the new??  or is there more to it than I think (soldering - calibrating etc)

2 - Any recommendations for a replacement valve?



  • crash2009
    crash2009 Member Posts: 1,484
    Yes, its pretty easy

      Use 2 wrenches, 1 for the gauge and 1 for whatever it is screwed in to.  There is a code requirement of having a 0-30 psi gauge.  If you want to get something more accurate you will need to install an additional gauge.  The norm around here is to add a 0-3 psi.  I ordered mine from gaugestore.com  Post a photo of how your gauge is now,  Here are a couple examples of how to add an additional gauge.  There seems to be a difference of opinion on what to use as a thread sealant.  Some have used RTV silicone, pipe dope, Teflon tape, or nothing at all.  I use Pro-dope and a couple wraps of Teflon.  Whatever you use, use it sparingly, and dont get any on the inlet.
  • Jshine
    Jshine Member Posts: 19
    pressure gauge

    Thanks for the info -

    Some pictures of the pressure gauge
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,216
    As mentioned you need the 30psi gauge

    That is for insurance purposes. If you can remove the gauge from that coupling and extend the pipe above the jacket you can install a tee and then install a new gauge. If you use a straight pigtail for the extension it will protect the new gauge from direct steam. If you put the new tee on the bull it will be less fittings to install the new gauge.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • crash2009
    crash2009 Member Posts: 1,484
    That looks pretty straight forward

     to swap out the 0-30 gauge.  Hang on to the coupler with a small pipe wrench and use a 1/2" or 9/16" to remove the gauge from the coupler.  Install a small pigtail into the coupler.  Build a small tree like picture 1, 2, or 3, and install two gauges on the tree.  You would need a 0-30 because of the code, and a 0-3 for the accuracy you desire.  It is preferred to use red brass for the tree.  Yellow brass is ok too.  Steel will have to be cleaned more often.

    0-3 gauge  http://www.gaugestore.com/prodinfo.asp?number=33020 

    pigtail  http://www.mcmaster.com/#pressure-gauge-siphons/=b5dj55

    Anyone else have a better or different idea? 
  • crash2009
    crash2009 Member Posts: 1,484

    I knew you needed that 0-30 for something important.  Not for code for insurance.
  • Jshine
    Jshine Member Posts: 19
    pressure gauge

    question - the 0 >3 psi gauge has the following spec - is the temp max ok - ??

    Media Temperature: 140º F maximum

    Ambient Temperature: -4º F to 140º F
  • crash2009
    crash2009 Member Posts: 1,484
    Temp Max 140

    If you install that gauge without a pigtail, you will fry it to a crisp.  The pigtail deny's the steam, but allows the pressure, to get to the gauge.

    Your existing gauge is a different kind.  It can be mounted directly in the steam.  If it was on a pigtail, it may have lasted forever.
  • Ed2
    Ed2 Member Posts: 17
    over pressure

    Our boiler has a vaporstat and a 0-30 psi gauge. If I added a low pressure gauge, say 0-20 ounces, and the system went over 20 ounces, would that damage the gauge or just max it out? I'd be glad to hear what others use for a gauge in a system with a vaporstat.
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,565
    installing a good low-pressure gauge

    don't forget to shut off the boiler switch several minutes before removing the old gauge, as your old gauge is so inaccurate at these low pressures, it would not show you anything, and there could still be enough steam to burn you.

    these gauges can stand a bit of over-pressure, so at the range which your vaporstat keeps the pressure, there would not be more than a pound or two over the gauge range.--nbc
  • SteamNoviceNJ
    SteamNoviceNJ Member Posts: 6
    Dunkirk and gauges

    I have a very similar Dunkirk boiler to that of your photo and replaced the old gauge in the same place with a 30lb, bottom-mount gauge.  I did this because I thought the gauge was broken.  While I had read Dan's books, I had not as of yet understood several things.  1. Gauges should be protected with a pigtail. 2. My one-pipe boiler operates at so low a pressure that the 30 lb. gauge would not register anything.  3. The 30 lb. gauge is installed by code (although it little of utility to a homeowner).

    My neighbor has a similar, one-pipe system recently replaced by a pro who installed the code-required 30lb. gauge.  However, his system does register...something like 3 or 4 lbs., I think.

    Anyway, I would like to add a pigtail to my 30lb. gauge and add a very low pressure gauge just to monitor what my pressures look like.

    I am curious - did you ever install yours and if so, where did you install it, what did you use and what did it end up looking like?

  • rrg
    rrg Member Posts: 37
    edited March 2014
    Here's another option, I would do 1 to 3 psi next time

    One pipe, gas system. Runs less than 1 psi.

    Here is the 5 psi with valve I added along with a new vaporstat but if I did this again I would go 1 to 3 psi for sure.

    2nd picture is the before, all stock, no changes.