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best location for 0 - 3 psi gauge

After improving my main air vent, I can no longer see the bump in pressure that occurs when my boiler goes on and want to install a 0 - 3 psi gauge as many suggest. But where is the best place?

I thought perhaps after the pigtail that goes to the pressuretrol - that way I could detect any pigtail issues that might (will?) eventually mess up the pressuretrol (which seems to be the system controller).  And the whole point seems to me to determine what pressure the pressuretrol is sensing. But how difficult is it to install here?

Is that why others have opted to make a tee on the gauge inlet and mount both gauges together?

Or am I better off mounting a vaporstat?


  • Joe V_2
    Joe V_2 Member Posts: 234
    I believe...

    Code requires a gauge with a scale twice that of boiler max pressure which in most residential cases is 15psi.  But more often than not, if the boiler is operating at two psi or less, you never see the needle move.  So to comply with code, and be able to see actual operating pressure, folks tee in a lower scale gage in parallel with the 0-30 and pressuretrol.

    The pressuretrol is the system's primary safety device and controller and should be checked at least annually by building boiler pressure and lowering the pressuretrol setpoint to ensure the burner extinguishes.

    Me personally, I also remove the tee and run a pipe cleaner through the pigtail to keep it clean and not allow the pressuretrol to fail.
  • I didn't mean to imply removing the 0 - 30 psi gauge

    I figure that 0 - 30 psi gauge had to remain to be in compliance.

    right now my 0 - 30 psi is all on its own - just attached to the boiler (internal siphon).

    The pressuretrol has the pigtail in front of it - no connection at all to the 0 - 30 psi gauge.

    So my question is:  put the gauges on a tee?, or put the pressuretrol and the 0 - 3 psi on a tee?
  • also what line size?

    I'd liike to be about to size the tees and pigtails I'm going to need.

    thx, again.
  • Joe V_2
    Joe V_2 Member Posts: 234
    Try this

    do a search on this board for "presuretrol"  you will find photos of actual installations that will help you.
  • ChrisJ
    ChrisJ Member Posts: 15,472

    This is where I have mine installed. Recently I added a small valve that allows me to release the vacuum that gradually builds between the pigtail and gauge. This modification is shown in the second picture. I used a long nipple to connect the gauge to keep it further from heat and water.


    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Hap_Hazzard
    Hap_Hazzard Member Posts: 2,849
    edited December 2013
    Here's how I did it.

    I put each on its own pigtail. The pigtails are mounted on ½" x ½" x ¼" tees connected to a ½" cross that connects the upper gaugecock to the boiler. The plugs in the distal ends of both reducing tees can be removed for cleaning or to add additional instrumentation.

    I put a shut-off valve under the gauge so I can turn it off when I'm not reading it--saves wear and tear on the gauge. I don't really care what it reads when I'm not looking at it. :)

    I also put a union under the pressuretrol. I call this, "being kind to your future self."
    Just another DIYer | King of Prussia, PA
    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
  • Orple
    Orple Member Posts: 35

    Really like the setup. It made me go back and rethink the 1/4 black pipe setup I was going to make. Unfortunately, running it in bronze with the specialized fittings more than tripled the price.

    I like the valve before the gauge, though. I've seen that on commercial setups, but didn't know if anyone did that on residential ones. I'd pay a few bucks for a valve if it saves me a gauge down the road.
  • Hap_Hazzard
    Hap_Hazzard Member Posts: 2,849
    Brass tends not to get clogged as easily.

    You can probably find better pricing on the bronze fittings if you shop around a little. My local Sears Hardware store, of all places, has a pretty decent selection of small, bronze pipe fittings at very reasonable prices. The cast bronze fittings are always less than those fancy machined brass ones and work just as well.

    Besides, you only need to do it once. It's worth spending a few extra bucks.
    Just another DIYer | King of Prussia, PA
    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
  • thx, I had not thought of using the water indicator inlets

    Nor had I thought of putting a valve in front of the gauge.

    BTW, has anyone tried Grainger for 0 - 3 psi pressure gauges? I was all set to buy one online at the gaugestore but the shipping costs increased the price 25%.

    Also, I know the pressuretrol has to be level and above the water line. Any other limits on its location (how high can it go)?

    Biggest question - how does one disconnect the pressuretrol? - spent alot of time online trying to answer the question, so I assume it must be easier than I think. Just unthread the current pigtail (mine is iron so I will definitely look for brass). What about the electrical connection - do you try and keep that connected while you insert the close nipples and union?
  • Hap_Hazzard
    Hap_Hazzard Member Posts: 2,849
    edited December 2013
    Now you see what that union is for. ;)

    You have to disconnect the wires to unscrew the pressuretrol from the pigtail, unless they're long enough to wrap around it six or seven times without breaking. You might just want to buy the union and a short ¼" nipple and keep them handy until you need to remove the pressuretrol for some other reason. Then that will be the last time you have to disconnect it to take it off.

    The pressuretrol should be mounted pretty high. It stays cleaner and is less likely to suffer heat damage. I wouldn't get ridiculous about it, but somewhere around the top of the boiler or a few inches above is reasonable. If you have one of the gray ones with the microswitch inside, like mine, it doesn't even really need to be mounted level. If you have one of the mercury switch models, like ChrisJ has, you need to mount it level and the loop of the pigtail should be perpendicular to its face. Otherwise the expansion of the tubing can slightly tilt the control and throw off the calibration.

    The upper gaugecock is actually a fairly common place to mount pigtails. It's usually the highest available place, and you want that because it's less likely to get plugged up with sludge than a lot of other places, especially if you blow down your glass gauge now and then. (That's what the ball valve on the lower gaugecock, shown below, is for.)

    Grainger sells good products. They're usually not the cheapest, but if they are in this case, I can't see why you wouldn't want to buy from them. The gaugestore gauges always struck me as a little flimsy. They work, but they aren't recommended for steam. They use a brass alloy capsule mechanism that tends to require recalibration periodically, but if you look at how the zero adjustment works it'll crack you up. I used to have a link for a nice, stainless bodied bourdon tube low-pressure gauge that was pretty reasonable, but I can't find it now. I never ordered one because the cheap gaugestore gauge is still working for me, proving they're really not so bad after all.
    Just another DIYer | King of Prussia, PA
    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
  • yes, I will probably save disconnecting the pressuretrol

    until Spring.

    In the meantime, my 0 - 30 psi gauge is sitting by its lonesome, so perhaps I will install some brass piping w/ a tee and a pigtail for a 0 - 3 psi gauge there.

    But eventually I would like to use something like what you've done so I get an idea of when the pressuretrol pigtail is clogged which will cause the pressuretrol to mess up. I see you used plugs on tees instead of elbows to maximize your flexibility. Is the 0 - 30 psi gauge somewhere - do you have to keep it?

    Can you provide a pic looking head on, between the pigtails? I'm trying to figure out if that is a 1/2" cross connected to the boiler input to the gauge.

    Thx for the info on the gauges - I was a bit worried about going elsewhere since folks seem to cite gaugestore alot. But I can drive to Grainger and FWWebb - helps alot w/ repeated trips and returns.
  • Hap_Hazzard
    Hap_Hazzard Member Posts: 2,849

    The 0-30psi gauge is mounted directly to the boiler. Other than taking it out now and then to clean out the tapping and re-zero the gauge I've left it as originally installed. This gauge is required by code, and it has to be maintained in working order.

    Yes, that is a ½" cross. I don't have a head-on picture of it, but I'll try to take one. There's a water heater and a condensate return in the way, but I'll see what I can do.
    Just another DIYer | King of Prussia, PA
    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
  • thx, looking for a way to attach 0 - 3 psi gauge before Spring

    And I'm afraid to touch the pressuretrol until the winter is over.

    Attaching a cross at the top of the glass or where the 0 - 30 psi gauge is (they are close to each other and above the water line on my boiler) - these are things I can do w/o shutting off the boiler? In other words, if I unthread the 0 - 30 psi gauge, water won't spill out of the boiler?

    thx again.
  • Hap_Hazzard
    Hap_Hazzard Member Posts: 2,849
    I'd shut it off.

    The tapping is above the water line, but if the boiler comes on you'll have live steam coming out. Wait for a warm day and turn the thermostat off. You'll want to shut off the lower gaugecock, remove the glass and the guard rods, then you can unscrew the upper gaugecock and the nipple it's mounted on. The tricky part will be finding a cross (or a tee if you only need one outlet) and two nipples that, together, equal the length of the original nipple. Otherwise the gauge glass won't be vertical. If you're okay with removing the lower gaugecock you can change that nipple to a longer or shorter one if necessary, and that will make it a little easier.

    This is the kind of thing where you want to make sure you have all your pieces lined up before you start pulling things apart.
    Just another DIYer | King of Prussia, PA
    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
  • rmoore007ri
    rmoore007ri Member Posts: 45
    adding gauges

    Here is a simple twin gauge setup on a Burnham Independence using the tapping where the 0-30 gauge was installed. No need for a union here. But DO put it all together first.

    In the meantime there is a Vaporstat in my future and that is definiely getting a union :-)
  • yes, repositioning the 0 - 30 psi gauge seems less daunting

    especially as a project to do in the short-term.

    these lines look like black iron - that is OK?

    I haven't checked the 0 - 30 psi gauge - is it just screwed on? And can be removed safely is the boiler is off?

    thx again.
  • Hap_Hazzard
    Hap_Hazzard Member Posts: 2,849
    Steel vs. Brass

    For some reason the brass pigtails seem to be less prone to clogging, You could use steel for the rest of it, I suppose, but you might get a little more galvanic activity at the joints. Besides, brass looks nice. :)

    Removing the 30psi gauge can be a bear. I had to take all the controls and trim off to avoid breaking anything and pretty much jump up and down on the wrench handle. You never know until you try though.
    Just another DIYer | King of Prussia, PA
    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
  • JamesC in Stamford CT
    JamesC in Stamford CT Member Posts: 95
    edited December 2013
    this is how I piped my gauge

    Thanks to the help and encouragement from the kind folks on this board, I was able to install a 3# gauge right next to my pressurtrol. Pictures and discussion at http://www.heatinghelp.com/forum-thread/135411/Any-Tips-on-unscrewing-loosening-an-old-pigtail in case that helps you consider how to pipe yours.
This discussion has been closed.