Click here to Find a Contractor in your area.
Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit

30psi and flowing water sound in pipe

BoscoBosco Member Posts: 22
Hello there, I have this 140k Weil McClain boiler for 2nd floor only, abt 1000 sq ft. I cant sleep at night because its got problems.

1) Is the boiler oversize or the water too low in the boiler? I see its only on for 2 min and temp. went from ~170 to 200 and stop, drops down to ~170 again and keep repeating.
2) I am hearing loud water flowing sound in the pipe. Is it because too little water or returning pipe too slow?
3) I try to release water from pipe and fill in water at the same time. I noticed as more water goes in, higher pressure it goes. Its sitting at 30psi, is it still at normal range? How do I add in more water without increase pressure level.

Any comment is much appreciated.


  • BoscoBosco Member Posts: 22

  • Jamie HallJamie Hall Member Posts: 13,852
    140K boiler for a 1,000 square foot apartment? Even assuming you are living in Winnipeg or Fairbanks, that's about 3 times the size it needs to be. Unless the apartment is an open porch...

    OK, that said. The rapid temperature rise indicates that water isn't flowing fast enough through the boiler. To get acceptable performance from the boiler, it needs upwards of 10 gallons per minute. Unless the pipes are large, that's going to be audible.

    On pressure, assuming that the boiler is in the basement, you need around 15 psi -- certainly no more than 20. There is an expansion tank on the piping; that should be charged with air -- with the tank drained -- to that value, and then it should be reconnected to the system and just enough water added to bring the system pressure to the same value. No more.

    You need to drain enough water from the system to bring it down to 15 psi or so for a starters, then make sure that there is no air lurking in the radiators. Then fire the boiler and observe the pressure change. It should be no more than a few psi. If it's more, either the tank is no good or it isn't properly precharged.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • neilcneilc Member Posts: 918
    everything Jamie says,
    and a good purge,
    but then I don't see anything for air elimination, on either boiler,
    so you'll want to add that, unless you have auto vents upstairs on the rads, do you ?
    what type rads upstairs ?
  • JUGHNEJUGHNE Member Posts: 7,408
    Is there a small auto vent next to the supply pipe on the top of the boiler?
    I'm guessing that your tank failed and is water logged.
    Does it feel heavy? when the water is cool it should be empty.
    There is an air Schrader valve under the plastic cap on the end.
    No water should come out if you depress it...only air...don't let all the air out.
  • neilcneilc Member Posts: 918
    you have better eyes than me, I missed that
  • DZoroDZoro Member Posts: 1,037
    Is this a new installation?
  • BoscoBosco Member Posts: 22

    Thank you guys so much for quick replies.
    Sorry, I was using a photo from the forum. I just attached the actual photo of the boiler.

    1) I just tried releasing water from pipe and tank to reduce pressure to 15. However, it went back to ~22psi as the boiler refills water by itself. If the vale is set at 15psi(#3 at the boiler photo), why would it refilled up to ~22psi.
    2)It actually turned off itself after reaching pressure limit, I had to press #3 at the boiler photo to make it run again.
    3) Can I release #1 valve to relief some pressure down to 15PSI in the boiler?
    4) I can just hear loud water flowing sound in returning pipe, why may be the cause for that? I have a baseboard system, not a radiator. There's no where to bleed air out.
  • neilcneilc Member Posts: 918
    well the new pictures change a thing or 2,
    get us one more from the hose and valve 2, down to the floor,
    that stock photo didn't have a way to isolate the tank, this one does,

    the noise is likely air trapped upstairs needing a good purge,
    shut the boiler off,
    close return valve(2.5, yellow ball valve) under the hose bib, use the fast fill, lever on top of fill valve(2), to raise system pressure up to 25 and open the hose drain, let it run till it's done burping, keep the pressure up till it runs solid water, release the fast fill and shut the hose when the system pressure is back down to 15.

    with that fill valve set at 15(tag), the air in the tank should be set there also, shut the boiler off,
    shut the valve above the tank, unscrew the tank, careful, it might be full and heavy, let it drain, then check the tank air pressure with it disconnected, set it to 15~16#, use a bike pump and good gage,
    put it back together and reopen that valve, drain the system pressure back down to 15 at that hose,
    is the little cap loose on top of that autovent? it should be.
  • neilcneilc Member Posts: 918
    and for your #1, you have a ball valve before the fill valve, shut that off, but keep your eye on the system while it's valved off,
    if it holds for a day or 2, then climbs again when you reopen, the fill valve could be adjusted
  • neilcneilc Member Posts: 918
    can we get a better picture of #3
  • BoscoBosco Member Posts: 22
    Thanks so much Neilc. I am a totally newbie.

    1) "you have a ball valve before the fill valve".
    Do you mean to turn off valve to stop automatic water flowing into fill valve then boiler, right? Just to test for a day or 2.

    2A) "let it drain, then check the tank air pressure with it disconnected, set it to 15~16#, use a bike pump and good gage,"
    Where to set to 15-16#? You mean use bike pump the air into the tank and check with gauge to leave as 15-163?

    2B)"put it back together and reopen that valve, drain the system pressure back down to 15 at that hose,""
    After put it together, which hose to use to drain sys pressure back down?

    3) I will take more good photos tomorrow when I go down again.

  • neilcneilc Member Posts: 918
    #1, yes, I see a yellow ball valve against the cellar wall, behind the boiler, shut it off until you need water pressure, keep your eye on the water pressure while it's off.
    #2, as you remove that tank it may spit at you, you can't set the air pressure in the tank with water pressure on the tank. there should be a air fill stem there on that tank, opposite the water connection, set the air pressure to 15~16psi.
    another way around this, with out removing the tank, would be to drain the system to 0 pressure at that same hose, you're not removing all the water, just til the pressure hits 0, set the air pressure to 15~16, then move on to the purge,
    #2B, your picture shows a hose on your purge valve, I am referring to that hose in all my call outs for water pressure.
  • BoscoBosco Member Posts: 22

    thank you guys.
    Why does air vent above the expansion tank need to loose a little bit? Will the boiler shut down itself if its tight. I also have a problem that once pressure reach ~24lb, the fire goes off and will not start again. Thermostat still had "heat on" and the computer panel in the boiler still show water temp. However, I had to press reset boiler to start running.
  • neilcneilc Member Posts: 918
    That little cap on the vent needs to be loose to allow air in that scoop and vent, to escape(vent).
    if it's turned down tight, it will seal as a cap does, and not allow air out.

    What water temp are you showing when your pressure is up at 24?
    I see a manual reset high water temp device, what is that set to?
    (grey narrow box w/ red button next to your gas valve in last pictures)
    You pressed this red button to reset the boiler, correct?
    Under the front boiler cover, what setting in there for hot water temp?
    more pictures , , , ,
    do you have your boiler manual ?
  • BoscoBosco Member Posts: 22
    Hi Neil, the narrow gray box with red button was set to 210. The water temperature setting after removing the boiler cover was set for 200. I do know not what temp was when the pressure is at 24lb, it should not be over 200 since it's the limit.

    Now I believe it's not the pressure that cause the stop of boiler. After I read the manual, it may be the the spill switch that has auto shut off function or the narrow gray box. ( What does this gray box do? Its set for 210, will it turn stop boiler if water temp is passing 210? Can I set to a higher limit?)

    I can take more photo next time.
  • BoscoBosco Member Posts: 22
    And yes I pressed the red button on the gray box to reset the boiler to run again.
  • neilcneilc Member Posts: 918
    that grey box is a manual reset high temp limit, and the red button is your manual reset, I would not mess with that right now, it seems to have worked.
    I would set the main control, under the front cover, down to 180,
    I assume you're not in northern Canada, or cold alaska, and have no need for 200* heating water.
    Dial your main control down to 180.
    You may be able to run cooler, 175, 170, but 180 is safe(comfortable) for now.
    And you shouldn't be tripping the high temp reset anymore.
  • neilcneilc Member Posts: 918
    edited November 21
    now please tell us you're not having to push the red button on the exhaust stack (your last picture)

Leave a Comment

BoldItalicStrikethroughOrdered listUnordered list
Align leftAlign centerAlign rightToggle HTML viewToggle full pageToggle lights
Drop image/file


It looks like you're new here. If you want to get involved, click one of these buttons!