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burnham steam boiler pressure issue

Hi all. I have a Burnham steam boiler in my recently purchased house. I am rather a newbie at this, but otherwise mechanically competent. So, here's my issue. My boiler was having issues coming on and staying on. But, tapping on the pigtail would cause the boiler to turn on and with a few more taps, turn off. So, I replaced the pigtail and pressuretrol and added a low-psi gauge off a T-junction from from the pigtail. Now, the boiler seems to start correctly, but the insurance-mandated 0-30psi gauge starts at ~10psi when cold and will climb to over 30 psi without the relief valve popping after turning on; I shut it down at this point for safety's sake. However, the new 0-15 psi gauge never gets past 0 psi.

My questions are:

1) Do you think the 0-30 psi gauge is bad?

2) If so, is it safe to replace it even though it registers 10 psi when cold? And, is the procedure just to unscrew the gauge and put the new one in?

3) If not, what else might be the problem?

Thanks in advance.


  • Zman
    Zman Member Posts: 7,542
    Lost art

    I think you were correct to install the new pigtail and pressuretrol. Since you were not scalded when you unscrewed the pigtail, I am thinking you don't have 10# of steam in the system when cold. I think your new gauge is measuring about 1# and is accurate.

    The system you are working on is an ancient art. It is not like most intuitive mechanical projects you have likely encountered. I think you should stop what you are doing and read "the lost art of steam heating"  available on this site. Once you have read the book you will understand the nature of your heating system.

    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • eclark
    eclark Member Posts: 33
    Similar Story

    I had a similar situation when I moved into my house a year ago.  I put in a new 0-30 psi gauge, added a 0-5psi gague on the pressuretrol pigtail and replaced the pressure relief valve.  I did it all the same time that I replaced the pigtail and pressuretrol.  I suspect they were all original to the installation which I'm guessing was circa 1992.  I figured it was cheap insurance to do it all and I slept better at night knowing what my pressures were.  At this point, you've done the most expensive part with the pressuretrol so might as well go the rest of the way, no?
  • Rod
    Rod Posts: 2,067
    Welcome to the Wall!

    Hi- Welcome to “the Wall” !  Sounds like you are on the right track. From what you say it sounds like you have a bad 0-30PSI Gauge. You can get a new one at Pex Supply on the internet or at your local heating supply.  Here’s a link to Pex Supply:


    The safety valve is set to open at 15 PSI so if the pressure went above that believe me you would know! Being in the same room when a safety valve opens on a steam boiler will really wake you up!!

    Residential steam systems operate at a pressure maximum of less than 2 PSI. You might want to get a 0-to 3 PSI gauge.I can’t imagine that the 0-15 gauge is much of an improvement over the 0-30 PSI gauge. You can get gauges here:


    Dan has written some very good books on steam heating which are available in the Shop section of this website. I would suggest you start with a book called “We Got Steam Heat! Here’s a link:


    It’s written for the homeowner new to steam heating and in a couple of evenings of reading will put your knowledge of steam heating light years ahead.  “The Lost Art of Steam Heating” was mentioned in another post. It’s a very good book also though I would read  “We Got...” as it gives you the basics and the vocabulary. (I did it the other way around and found that it would have been better to read “We Got ..” first!)

    I would also strongly suggest that you get a pro in to check over your boiler. Do you have a I&O manual (Installation & Operating) for your boiler? If not, let us know the model number and size and we can probably find one for you.

    - Rod
  • whosawhatsa
    whosawhatsa Member Posts: 9

    Thanks for all the info. It's really great to have such a helpful community. I did pick up We Got Steam Heat recently and have started to read it. Once I'm finished, I will also grab Lost Art. I don't know my model# offhand (and I'm at work), but I will take a look once I'm home.

    I will grab a new gauge on my way home and replace it later today. Hopefully that will do the trick. I just want to verify that the pressure readings on both gauges should be approximately the same. I wasn't sure before since the gauges are at different heights compared to the boiler.
  • Rod
    Rod Posts: 2,067

    Hi- The Burnham  0-30 PSI gauge is normally attached directly to the boiler without the benefit of a pigtail. If you notice the picture of the Burhham gauge in the link I sent you, you will see it has a wording on the face of the gauge "Internal Syphon".  This means it has an internal "pigtail".  All gauges need either an internal syphon or a pigtail to protect   them from live steam.  If you attach a regular gauge (non syphon) directly to the boiler (without a pigtail) it won't last long.

    Pigtails- Use a bronze one when you replace the pigtail as they are not as susceptible to clogging as a steel one.

    - Rod
  • whosawhatsa
    whosawhatsa Member Posts: 9
    water level

    Thanks for the info. I installed the new gauge and it seems to be more accurate at this point; the old one was clearly bad and clogged with gunk. I now have two more questions that you maybe can help with.

    1) After 15 min or so of running, neither gauge showed any pressure (needle was against the pin). Is this ok? I eventually shut the boiler off due to the issue in Q2.

    2) The water in the glass pipe eventually disappeared entirely. There is a low-water cutoff, and I had set the water level by opening the feed valve until the system wouldn't take any more water (~ 4" above the center of lower gauge glass tapping), which is the recommended amount from the little documentation I have. I then closed the feed valve. Does all this seem correct? Or, should I bring the water level up a bit further?

    Thanks again. You guys rock.
  • BobC
    BobC Member Posts: 5,470

    It would help if you could post pictures of the boiler and the piping around it.

    Unless the gauge you bought was "internal siphon" type gauge it needs a pigtail between it and the boiler. Most gauges will not last long if they are in direct contact with the steam. Boilers have a pressure regulating device that should limit the pressure to less than 2 PSI and hopefully less. What is your pressuretrol set to?

    You said the water in the sight glass disappeared after a while, did it reappear after the boiler was shut down (say 15-20 minutes or so)? You also said you filled the boiler initially until it would not fill any more (top of the sight glass), Boilers should ONLY be filled to the normal water line, that is usually 1/2 to 2/3 up the glass. When the boiler is making steam the water line should not fluctuate more than 1/2", if it does the boiler pressure is too high OR the water is contaminated with oils.

    You should buy some of the books on this site so you'll understand how steam systems work. "We got Steam Heat" is very basic while "The Lost Art of Steam Heat" will give you a very good understanding of how the system should work and will give you enough information so you can work on the steam side of the system yourself (not the gas or oil side).

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • whosawhatsa
    whosawhatsa Member Posts: 9
    water level

    It was not an internal siphon gauge, so I swapped the old gauge back in and ordered a new one (now that I seem to have verified that the gauge was indeed bad), and I will replace it once it is here. The pressuretrol is on the lowest setting 0.5 psi + 1 psi differential. The water did come back once it cooled. And, I did not add water until it was at the top, but when the water automatically stopped flowing into the system, which was only about 1/5 the way up the sight glass OR ~3.5" above the lower valve of the sight glass. My documentation mentions that this is the correct level, but also describes a low-water cutoff at 2.25" above the lower valve, but this did not happen when the water disappeared. I have one book and will get the other once I have finished.

    Thanks for the help.
  • whosawhatsa
    whosawhatsa Member Posts: 9

    here is an image of my setup ... don't mind the open wiring, I just finished replacing the thermostat and added a new wire.
  • Rod
    Rod Posts: 2,067
    Boiler Model

    Hi- What is the model number of your boiler? There should be a placard on the boiler that

    has this information.  As Bob mentioned it will be a big help if you could post photos so we can see how your boiler is piped/configured.  Take the the photos from back away so this includes the piping around the  boiler. This will allow us to trace out the piping and see how it is hooked up.

    - Rod
  • whosawhatsa
    whosawhatsa Member Posts: 9
    edited September 2013

    The model # is 406b. And, is this the view you were looking for?
  • BobC
    BobC Member Posts: 5,470

    I misread your explanation about filling the boiler to a point 4" above the bottom sight glass valve, my bad. Your old gauge was bad but be aware that new pressuretrols have been known to be wildly inaccurate so it's important to have a working gauge so you know what the pressure really is.

    If the boiler matches the rest of the system very well it is possible you never build any real pressure. Do you know how many sq ft of steam the boiler is rated for and do you know what the EDR (surface area in sq ft) of all your radiators is?

    When you replaced the pigtail did you check to see if there was any gunk

    in the port it screws into? Sometimes you get a buildup there that acts

    like a flap, it covers the port as pressure just starts to build and

    the pressuretrol never sees the real boiler pressure. If it looks like

    there is some crud in that port try to clean out around that port with a

    wire or wire tie.

    Is the water in the gauge glass dirty and does it bounce around a lot before disappearing? The water level should be reasonably steady if the water is clean and the pressure is low,

    If the boiler water is contaminated with oils it will be very unstable as it begins to build steam and may need to be skimmed.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • Disappearing water

    What you need is a 0-3 psi gauge on the same pigtail as the pressuretrol. With that, you will see what the exact pressure is when the water disappears. Gaugestore.com is the source for these.

    How clean is the water in the sight glass?

    We had a disappearing waterline mystery, and discovered a horizontal pipe in the return which would hide water as the pressure rose. This pipe was a couple of inches above the waterline height, and would hide all the water until the LWCO would shut off the burner. Dropping all the wet returns to the floor cured this. Some installers will try for a quick fix by putting a check valve in the lowest part of the wet return to prevent water from leaving the boiler, but this can also keep water from flowing back into the boiler when it needs it most (ie. when making steam).--NBC
  • Rod
    Rod Posts: 2,067
    Need more info about your system

    Hi- From what info I could find ,your boiler, a Burnham 406B, is a pretty old boiler probably about 20 years old or more. Are there any dates on the placard? From what little I could find out it seems to be rated for 447 sq. ft. of steam.

    Thanks for posting the pictures. Could you take some from farther back so we can see both the boiler and the piping going to the steam mains.

    It would be of help if you could tell us a little more about your system.


    1. What type of system do you have? You can identify this by the number of pipes going to each radiator. 1 pipe = a 1pipe system, 2 pipes = a 2 pipe system. Also 1 pipe systems have a radiator vent attached to the radiator.

    2. How many steam mains do you have?

    3. How many return pipes do you have? These are the pipes leading fron the ends of the steam mains back to the boiler.

    4. Do the mains or the returns have a main vents attached to them and if so what is the make and model? (A picture of these helps)

    5.Have you ever operated the boiler and if so how well does it heat the radiators?

    6. Is there a make and model number on the Low Water Cut Off?

    At this point I think you need to have a good steam pro look over your boiler and system. Tell us where you are located and maybe we can recommend a good steam pro local to you.

    - Rod
This discussion has been closed.