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Low Pressure on New Steam Boiler

Norm Harvey
Norm Harvey Member Posts: 684
Judging by the pipe dope fingerprints and smears all over the gas piping, I would say you did that also.

It would be tragic to read about a catastrophe in the newspaper. I assume you do not have a license to perform gas work, and I highly doubt your homeowners insurance will pay for your new house.

How about we start following local laws and building codes as a start.
"We see the world as WE are, not as IT is, because it is the "I" behind the EYE that does the seeing"


  • Ming Moy
    Ming Moy Member Posts: 4
    Low Pressure on New Steam Boiler

    I have just installed a new Weil McLain steam boiler in the rear basement of my two stories house. After I started it up, the radiators in the rear and middle of the house heated up. The radiators in the front of the first floor warmed up. However, the baseboard radiators in front of the second floor did not getting any steam at all (all radiators are cast iron except for these two). I have done the following trouble shooting on the steam system.

    1. Leakage inspection on the boiler and piping has been done. No leakage was detected upon inspection.
    2. Balancing of the steam system has been done by replacing air vents on all radiators and main pipe in basement. After the balancing has been done, steam has distributed much better. Steam occasionly heated up the radiators in the front of second floor(before balancing those two pipes to the radiator did not get steam at all).
    3. High limited on boiler has been adjusted from 2PSI to 6 PSI. It did not affect the boiler steam pressure.
    4. Orifices on fire tubes have met Weil McLain' 2.54 mm requirement.
    5. If the temperature is being raised to two or three degree difference, the boiler will stay on for about 45 minutes. The boiler created a little bit of pressure. The pressure gauge move a little bit. Then all radiators heated up.
    6. Radiators heated up by turning it on in the next morning because boiler was turned off for inspection during the night.
    7. I have done the heat loss calculation and heat area of the FTR for my house again. It appears that the radiators has no more than 300 square foot of heating area and heating loss is 110000.00 BTU. They both met the net rating of the Weil McLain EG-50 steam boiler which are 454 sq. ft. and 109000 BTU.

    Is the boiler undersized? Is the gas pressure affected this? The location of the thermostat is improper? What else should be done to create much more pressure in the boiler? Please advise.


  • Chas_2
    Chas_2 Member Posts: 104
    boiler pressure

    Your pressure is to high ,every steam system i have installed has ran no more 1 1/2 psi and some of these homes are 10 to 15000 sq ft and they mostly work on ounces of pressure not pounds ,i would make sure your near boiler pipe is to manafucture specs at the very mimiun ,next i would check to see if the boiler is surging and or foaming ,skim the boiler of surface impurities (cutting oil and possible flux ) Is you boiler piped in steel pipe ,and are all your steam supply line well insulated ? next question are you sure all your raditor valves are open and properly pitched ,when installing new vents did you re tapped the tapping to help remove the crude and ensure that the vent tapping is clear lots of things to look at if the header is getting hot then don't look at the boiler to solve your promblems nosey around the promblems is either in venting , distrubution piping ,lack of insulation or improper near boiler piping producing wet steam which like a hippo in the water is quite lazy ,can you post some pics of your boiler and it's piping also on that baseboard more then about 6 ft and you will occur promblems and for myself i usually pass on the remove the rad and but in base don't want to deal with under performing baseboard in a steam system to it does not belong peace and good luck clammy
  • J.C.A._3
    J.C.A._3 Member Posts: 2,981

    First off...GREAT name!

    #B, TURN THE PRESSURE DOWN!!! (my caps) Hell, the Empire State Building runs on less pressure than that.I wish I had a buck for every job I've gone to where the pressuretrol gets turned UP to "fix" the problem....and the truth of the matter is, it MORE often than not is the CAUSE of the problem.

    Part 3, I believe you have a water trap somewhere leading to those baseboards. Ya gotta get to the piping and see what is pitched the wrong way. I'll bet you a nickle you'll find it!

    Section D....Here's the rule according to our esteemed host. Steam up....air out....water back. Which one is your problem?

    Good luck, and let us know how you make out. Chris

  • Jamie Hall
    Jamie Hall Member Posts: 22,875
    Ming --

    the fact that most of the radiators get heat indicates that there is some reason why those baseboards don't.

    First -- step one, now! -- adjust that steam pressure down. If you are stuck with a Pressuretrol, you'll probably not be able to go much below a pound or so, but go as low as you can. If you have a Vaportrol (which you should), I doubt you'll need more than 10 ounces, probably less. Everything will work a lot better.

    Second -- there has to be some reason, unique to those baseboards, why the steam doesn't get to them. Bad vent? Bad pitch to a pipe somewhere? Bad pitch on the baseboards themselves? Trace the pipes and check everything involved; I'll bet you find the problem.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Ming Moy
    Ming Moy Member Posts: 4
    Low pressure on new steam boiler

    Dear Chris, Clammy and Jammie:

    Thanks you for your time and suggestions. I wish you a happy holiday. It has been almost a month since I posted up questions about my new steam boiler. I have adjusted the boiler pressure to 2.5 pounds and relocated my thermostat to the second floor. It seems working better than before. The boiler cycles less. The two pieces of the baseboard radiator at the far end of the second floor heat up more. Even though I still have questions after I observed my boiler. I hope this essay like questions would not bother you.

    1. The boiler water level is about 3/4" less than half way of the sight glass. Is this the normal water level?

    2. After the boiler fired up, its water level dropped down to the bottom of the sight glass slowly (invisible from sight glass) during the operation. The water level eventually gets back to its original position after it stopped running. However, I heard water dripping inside the boiler. I am wondering what is wrong with it (see attached photos).

    3. The boiler cycles every thirty five minutes for four minutes after I relocated the thermostat to the second floor. Is this normal? Should I raise the boiler pressure to keep it running longer? How should I reduce the boiler cycling time a bit shorter?

    5. Since the boiler cycles every thirty five minutes, it takes the boiler about an hour and Twenty minutes to heat up the radiators. I kept hearing the air venting out of the radiators even though the radiators heated up. Is the boiler undersized? I calculated the radiator heating area and heat loss of my house before I selected the boiler. The radiator heating area is much less than what the boiler provided. However, the heat loss of my house 110,000 BTU does not included any safety factor included). Should I include 30% of safety factor? Should the boiler be selected upon the boiler output or the IBR rating?

    6. How should I adjust the gas valve to up firing the boiler to get more pound of steam?

    7. Those two pieces of 6¡¦ baseboard radiators in front of the second floor still heat up partially three to four feet only. Should I replace them with the cast iron radiators to get better performance?

    8. The temperatures between the first and second floors are quite different. Will the installation of a controller to take the average temperature of the first floor and second floor solve the temperature difference? How does it work?

    9. If I set my boiler at 2.5 pound pressure, what the cut-in and cut-out pressure are, respectively.
  • JohnNY
    JohnNY Member Posts: 3,226
    Ming, I'm sorry but..

    your boiler is horribly installed.

    You need to have the piping redone by someone who knows what they're doing.

    Good luck with that.

    To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"
    Contact John "JohnNY" Cataneo, NYC Master Plumber, Lic 1784
    Consulting & Troubleshooting
    Heating in NYC or NJ.
  • Brad White_184
    Brad White_184 Member Posts: 135
    I was going to say...

    Thank you, John, for stepping up and beating me to it.

    Ming- we are just the messengers so bear with us...

    A few thoughts:

    The riser off the boiler has good initial height but needs to have an equalizer. You do have an excellent opportunity for a dropped header. This will take that initial rush of wet steam, separate the water and send it back to the boiler without having it go out to the system first. (That low-point drip is barely a wish- water will breeze on by when the boiler is making steam.)

    I have no idea what the return connection piping looks like and if you have a Hartford Loop. I cannot see an equalizer so doubt the existence of a Hartford Loop.

    Where are you located?

    As John said, get that boiler piped properly and enjoy the benefits. I admire your sticking with steam and wanting to do it correctly. Let's see where we can help.
  • tim smith
    tim smith Member Posts: 2,738
    I second Brad's & John's comments

    That is a very poor at best installation of a boiler and has to be repiped to correct or it will not work right. Good Luck.
  • Ming Moy
    Ming Moy Member Posts: 4

    Thanks for your comments. Do you think it will solve all my problems if I have the boiler repiped with an equalizer and a hartfort returen connection? Can you give me an idea of how this equalizer works? I still have questions did not have ansewers yet.


  • Ming Moy
    Ming Moy Member Posts: 4

    Thanks for your comment. Please don't laugh at me. The current hookup of the boiler is my idea. This is my first experience of heat loss calculation, selecting boiler, design boiler hookup and fabrication pipes. My friend and I hooked it up together. Is it a good idea to have that low point drip remained? Or I could get rid of the drip. Do you think it will solve all my problems if I have boiler repiped with an equalizer and a hartford connection? I will post up the sketch of the boiler hookup for comment before I fabricate and install the pipes. Please tell me how these equalizer and hartford return work. By the way, I still have questions did not have answers yet.


  • JohnNY
    JohnNY Member Posts: 3,226
    The best answer you can get...

    ...is to open the installation and operation manual. Look at the piping diagram and follow it without deviation.

    Steam is not a forgiving heating medium and this is no time to experiment.

    Until the boiler is installed properly, there is not much to talk about.

    To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"
    Contact John "JohnNY" Cataneo, NYC Master Plumber, Lic 1784
    Consulting & Troubleshooting
    Heating in NYC or NJ.
  • David Nadle
    David Nadle Member Posts: 624

    Not to mention the missing drip leg...
  • Plumber7
    Plumber7 Member Posts: 19
    Cast iron bushing

    Ming, Where I'm from you can't use a cast iron bushing on gas. They will crack and leak. I would also use straps made for the piping you are using, not band iron. And about the steam installation....what they said. Tom
  • Ming, look at this

    It might help. Follow the instructions, though, over anything else written.


  • Brad White
    Brad White Member Posts: 2,398
    No one is laughing at you, Ming

    We all want to help and are very glad you checked in. Let;s get you to a safe and efficient solution.
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"

    -Ernie White, my Dad
  • Don't feel bad, Ming

    years ago when I installed my first steam boiler, I did almost everything wrong too. The strange thing was, that job still worked! It was at a neighbor's house and I still see it- and cringe- occasionally. But now I know just why it works, in spite of being my rookie effort. This was, of course, prior to my discovering the book "The Lost Art of Steam Heating", and The Wall wasn't even a gleam in Dan's eye at that time either.

    Get "Lost Art" in the online store of this site, and re-read the Weil-McLain installation manual after you read the book as far as the "near-boiler piping" chapter. Then it will make a LOT more sense- it did for me all those years ago.

    To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"
This discussion has been closed.