The Wall
Forum / Strictly Steam / wicked water hammer and boiling in pipes
  • Post a Reply to this Thread

    wicked water hammer and boiling in pipes (31 Posts)

  • gypsy gypsy @ 6:12 PM
    Contact this user

    wicked water hammer and boiling in pipes

    Hi there, wondering if you all could shed some light on this system.   We are having what sounds like water boiling in the steam runs and from where one one run turns to go upstairs all the way to the second floor radiator.  We are also having water hammer that vibrates the floor and furniture.   Ive attached some pics.  Any insight is much appreciated.
  • nicholas bonham-carter nicholas bonham-carter @ 6:57 PM
    Contact this user


    from what I can see, the dry returns seem to join up well above the waterline of the boiler, and those main vents seem very small.
    I don't see a pressure gauge, so it's possible your pressuretrol is allowing the pressure to exceed the maximum of 1.5 psi.
    get the pressure down, and verified by a 0-3 psi gauge [], and get a couple of gorton 2's on the reworked dry returns, and see if the noise stops.
    once you are certain the header is correct, then put some fiberglass insulation on the supply pipes.--nbc
    This post was edited by an admin on April 7, 2013 6:58 PM.
  • gypsy gypsy @ 7:46 PM
    Contact this user


    Thank you for the reply Nicholas.  Ill see if i can get the pressure checked.  What do you mean by making sure the header is correct?
  • Jamie Hall Jamie Hall @ 8:20 PM
    Contact this user

    A couple of questions...

    first, what is the make and model of the boiler?  I can't quite make it out in the photos, and I would like to see if I can get hold of the installation manual and check the header installation.  It is probably correct, but there is a chance it might not be.  If it is correct, you are going to have to watch the water level like a hawk, particularly when it is steaming, as having the connection to the riser as low as that makes it very easy for slugs of water -- not just droplets -- to get into the riser and on into the rest of the system.

    I am not concerned about the dry returns coming together above the water line, but you could probably use bigger vents -- but that won't affect either the water hammer or the boiling noise in the pipes.

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

    Hoffman Equipped System (all original except boiler), Weil-McClain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • gypsy gypsy @ 8:56 PM
    Contact this user

    boiler make

    Thank you for the reply Jamie.  Its a dunkirk psb 4d.  Ive been told the piping isnt right, and it has been partially repiped-i didnt have the funds to tear it all out and start over- and i was told the problem should have gone away.  There was no boiling water in the pipes before and the hammer is worse now. The waterline never seems to move anymore, not even a bounce.

    The vents and returns wont affect the hammer?  I was told those and the returns were put in to stop the hammer.  Is that why they didnt help at all?   Im asking because now im being told that they want to run 30 feet of a new return -which will entail asbestos remediation-because the ones in the pictures didnt fix the problem.
    This post was edited by an admin on April 7, 2013 9:04 PM.
  • nicholas bonham-carter nicholas bonham-carter @ 10:20 PM
    Contact this user

    Who is telling you that?

    Luckily, the winter is over, and you can take your time to learn about the system, with our help, and make the changes in the summer, maybe even by yourself!
    You will need better main vents. Don't listen to anyone who might say that the radiator vents will solve the problem, because they will not.
    Now why would new returns be needed( 30 ft).? Are they leaking?
    If the dry returns are joined above the waterline, you could get some water-hammer in the pipes. Jaimie thinks the chance of that being a problem is remote; but it could be one of the things on your list, if you can feel the hammering in that area.
    There are many women here who have learned how to diagnose the problems with their systems, and also to make some of the repairs themselves, as a result of information from this site.
    Steam ladies, step up to the plate here, and give Gypsy some encouragement.--NBC
  • gypsy gypsy @ 10:39 PM
    Contact this user

    Yes please!

    The plumber who put the vents and returns in instead of repiping the loop and header to try and save me some money is the one telling me i now need the asbestos remediation and a 30+' return.  NO, they are not leaking but with the hammering and boiling, im scared they will!  Yes, i was also told to replace some of the radiator vents and did, and one that they put in malfunctioned and filled a 2nd floor rad with boiling water that make the hammering even worse until they figured it out.  I wish the winter being over was helping, but that water heater is causing the same problems every time it kicks on. 

    Yes please ladies, anyone, pitch in!  Thankfully (or maybe not, i was able to run downstairs and shut the system off once this winter because it almost blew up-the water tank was piped wrong, but) This is literally driving me insane.  Because of the noise, I have not had a full nights sleep since this one went in and (if that isnt bad enough) at its whim the heater cranks the heat up sometimes by 10 or more degrees regardless of a call for heat.  Any help is greatly appreciated before i go downstairs and take a sledgehammer to the whole thing.

    The floor above the boiler shakes when the hammer gets going as does the floor all the way to the corner where the pipe goes up into a wall.  The majority of it is on the left steam run and for about 15' from the boiler.  Would this be where it would happen if it is from the returns being above the water line?
    This post was edited by an admin on April 7, 2013 10:49 PM.
  • Rod Rod @ 3:01 AM
    Contact this user


    HI-  I looked over your pictures and it would seem that you have two steam mains. The one I labeled "Main A" appears to be a counter flow main and the main that I labeled "Main B" appears to be a parallel flow main. Check and see if the "Slope" the mains is in the direction I indicated by the purple arrows. (See attached photo) 

    The other thing I noticed is that in the photos it doesn't show a pressure gauge. Is there a pressure gauge on the boiler? You should have a 0-30 PSI pressure gauge as this is required by code. Most of the people on here also install an addition 0-3 PSI pressure gauge as it makes it easier to read low pressure. The pressure of your system shouldn't run higher than 2 PSI.  Running at too high a pressure can be the cause the hammering that you are experiencing.

    The piping in the yellow boxes ( see attached photo) should be eliminated as it causes the steam pressure to "short circuit"  to the return. Like wise the Main Vent labeled "Main Vent "A" (circled in yellow) as it has no benefit where it is located, On a counterflow main, the main vent should be located at the far end of the main from the boiler just after the last radiator lateral.
    The Main Vent  (Circled in red) labeled "Main Vent "B" is in the correct location when used on a Parallel Main.  Let us know what the make and model number is as I suspect it is undersized and more venting capacity would be of help to you.

    While you need to eliminate the piping outlined in yellow, the drip pipe on the counter flow main needs to be  lead down so that it can join the return piping at a location well below the boiler's waterline.  On a counterflow main this drip line drains the returning condensate back to the boiler so that it doesn't interfere with the steam supply from the header.  All this maybe a bit confusing so don't hesitate to ask questions.
    - Rod
    This post was edited by an admin on April 8, 2013 3:08 AM.
  • gypsy gypsy @ 9:50 AM
    Contact this user

    yellow and mains

    Hi and wow.  lots of info Rod, thank you.  main b is very slightly pitched towards the boiler.  It had more of a pitch but was raised when the new boiler went in.  Main a is pitched away from the boiler and always has been(its welded that way).  there was an attempt to correct this by pulling down on it.  This did not change the pitch and screwed up the radiators upstairs(dont ask).

    about the pipes in yellow.  Im not sure i understand.  These were added with the vents to stop the hammer, along with adding the drip pipe on a and changing the return on main b back from copper to iron.  It didnt work(actually i think its worse), what do you mean it causes the steam pressure to short circuit?

    The boiler is a dunkirk psb 4d,  and i think there is a pressure gauge built right in to the top of the boiler.  It says internal siphon psi and reads .5 when the boiler is running for heat.  would it being undersized cause the radiators to sound like they are heavy breathing and the boiler to turn on and off when calling or heat? I feel silly asking that one, but so far ive been told its normal, but have never heard this before on any other system.  Thank you for all the info.
    This post was edited by an admin on April 8, 2013 10:10 AM.
  • gypsy gypsy @ 3:10 PM
    Contact this user


    Thank you for the diagram.  Im wondering-and not that i doubt you, im just looking for more information for my plumber-if there is a consensus about this piping in yellow shorting out the boiler cycle.  it seems to make sense to me, but i have just recieved an estimate from my plumber saying that re-piping wont fix it and they are suggesting removing the water heater first then seeing how the boiler reacts.  the estimate is 7500 total and 2300 just for the hot water heater.  Considering everything i have spent to try and fix this so far, im just wondering if you all have any input as to whether this might work.  Thank you again for all your suggestions and thank you in advance.  
  • Rod Rod @ 3:49 PM
    Contact this user

    Get a Real Steam Pro!

    Hi- As one of the rules on the "Wall" is that pricing is NOT discussed so I can't help you with your figures.
    As to your situation - Somewhere I've read a saying that went,  "All steam pros are good plumbers, however, all plumbers aren't good steam pros!" and from my personal experience this seems to be the case.
    From what I can see in your pictures and from what I have read as to "future plans" it would seem to me that you REALLY need to find a steampro.  Fortunately there is a very good steampro in your area. If it were me, I'd contact Charles Garrity,
    He is a contributing member of "the Wall" and from his posts and from the positive remarks of other homeowner wall members, who have used his services, is obviously an excellent steampro.
    Pursuing the direction you are now going seems to be "just chasing your tail" so to speak and not likely to result in a satisfactory conclusion.
    - Rod
  • Zman Zman @ 8:27 AM
    Contact this user


    Your boiler should not be boiling and heating the house during a hot water call. Their is an aquastat (gray box) on the pipe between the pump and the hot water heater. What is it set to?
  • gypsy gypsy @ 9:06 AM
    Contact this user


    its set at 180 and the temp on the heater 160 with a mixing valve. 

    Any idea why it is creating heat?
    This post was edited by an admin on April 9, 2013 12:50 AM.
  • Jamie Hall Jamie Hall @ 9:45 AM
    Contact this user

    At least one step ahead...

    The steam takeoff and wet return on the boiler are at least in the right tappings... I've seen it done otherwise.

    Looking at your piping some more, I agree with Rod -- that pipe in the yellow box isn't helping.  But I see another thing which I really don't like at all.  The main which he has labelled "A" comes off the side of the header pipe.  No.  That is just not correct.  Since everything is nicely threaded, it shouldn't be all that hard to fix, but that pipe needs to come off the top, like the other main.  I can't guarantee that it will help to do that -- but it certainly won't hurt.

    Do you have Dan's books?  Especially "Lost Art"?  If not, you should order it -- it will help you to understand your system.

    Water hammer really isn't rocket science.  The trick, though, is to figure out how water is getting into the steam mains (or, occasionally, into the returns and pooling) -- which may be quite natural and, if it is, not to be worried about -- and then to figure out why it is getting trapped.  Water hammer occurs -- as the name suggests -- when the steam (or, rarely, venting air) can pick up a pool or slug of water and push it along a pipe, rapidly, to where the pipe changes direction; the steam can make the corner, but the water can't and hits with a bang.

    So... on a single pipe steam system (well, any system, really!) one of the first things to do is to make sure that all the pipes are sloped so that water can drain back (or forward!) to a point where it can drop down to either a wet (near floor) return or to the boiler return.  This is especially important if you have a counterflow main (that is, the steam is going one way and the water is draining back the other).

    So -- next thing to do, some sleepless night, is to take a very good level and check every single section of pipe to make sure it is sloping properly.  Then we can eliminate that as a source of hammer and start looking elsewhere!

    Oh yes -- and fix that piping.

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

    Hoffman Equipped System (all original except boiler), Weil-McClain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • gypsy gypsy @ 9:58 AM
    Contact this user

    i thought that was odd.

    The main coming off the side of the header pipe... and  thank you for the information!
    This post was edited by an admin on April 8, 2013 8:09 PM.
  • RJ RJ @ 10:36 AM
    Contact this user


    Dont forget to insulate all steam piping, uninsulated pipes can cause problems
  • gypsy gypsy @ 10:38 AM
    Contact this user


    Will do as soon as i can get what piping needs fixing fixed.  They have never been insulated though, so im not sure how much that is adding to the problem.
  • RJ RJ @ 11:06 AM
    Contact this user


    Uninsulated piping have a heat loss 5 times greater than insulated pipes, uninsulated pipes can cause a mid-cycle water hammer problem that wasnt there when piping was insulated,  this is all in Dans book, Lost art of steam. In my exp. I also found uninsulated steam risers in bldgs can cause banging and ticking in piping
  • Jamie Hall Jamie Hall @ 12:26 PM
    Contact this user

    Ah ha!

    "main b is very slightly pitched towards the boiler.  It had more of a pitch but was raised when the new boiler went in. "  Tally ho!  There's part of your problem!  A counterflow main can't be pitched "very slightly".   I don't happen to have the manual here right now, but a quarter to a half inch per foot sticks in my mind as an absolute minimum.  Check the whole length of the thing, and get it dropped enough so that it really truly slopes towards the boiler all the way along.

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

    Hoffman Equipped System (all original except boiler), Weil-McClain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • gypsy gypsy @ 2:01 PM
    Contact this user


    Thank you Jamie.  It looks like it has to come back down a lot. 
  • Rod Rod @ 2:14 PM
    Contact this user

    Steam Mains

    Hi- Well I’m now a bit confused myself as to what type of steam mains you have.
      Let’s go back to the basics. Steam mains carry water (H2O) in two forms: 1. Steam and 2.Condensate (water). Steam flows (floats)  along in the top half of the main and condensate (water) flows in the bottom half of the main.  When both the steam and water flow the same direction we call it a “Parallel Main” When steam and condensate (water) flow in opposite directions we call it a “Counterflow Main.”
    Since steam is a gas, it is able to travel in any direction, up, down, sideways. Steam floats along and travels from areas of high pressure to areas of low pressure. Condensate (water)  on the other hand, is a liquid and it needs slope (like a children’s slide) to make it travel back to the boiler. I find it helps if you think of yourself as a molecule of steam traveling out to the radiator and then condensing back to a liquid (water) and then sliding (along with lots of other water molecules) ideally the slope is a constant “down hill” and we all quickly get back to the boiler. If say the slide changes direction and suddenly goes “up hill” a lot of molecules are going to get caught in the “dip” which causes a “traffic jam” resulting in a backup of water molecules. This backup can interfere with the steam stream and cause it to “collapse” (condense) back to water. 
    Counterflow Main- On a counterflow main, the highest part of the main in the end farthest from the boiler. The steam steam travels “up” the main and the condensate (water) flows “down” the main back to the boiler. (See attached diagram) The pitch on a counterflow main should be 1 inch in 10 feet and the slope should be constant with NO dips! The main vent on the counterflow main should be located at the farthest end of the main away from the boiler.

    Parallel Main- On a Parallel flow main, the highest part of the main is the end closest to the boiler. The steam travels “down” the main from the end above the boiler to the end farthest away from the boiler.  The condensate also travels towards the end of the main farthest away from the boiler into a return pipe that returns the condensate back to the boiler The return pipe naturally has to be sloped so that water is able to run downhill back to the boiler.  The pitch on a Parallel Main /return needs to be 1 inch in 20 feet. 

    You need to check your steam mains and determine what type they are and also check for sag (“dips”) in the piping.

    Yellow outlined piping- As mentioned above, steam travels from areas of high pressure to areas of low pressure. High pressure, even though it may only be 1 PSI or less is provided by the boiler and low pressure by the escaping air from the vents or by vacuum in the radiators caused by condensing steam.  This pressure differential is what moves the steam from the boiler to the header pipe, continuing  up the risers and through the steam main and in the radiators. The yellow outlined piping connects directly between the start of the steam main and the return pipe which provides a path for the steam to travel directly to the area of low pressure (the end of the steam main/ return pipe without going to the radiators (“short circuiting”)

    Let’s first check your steam mains “A” and “B” and determine what type they actually are and then we can continue on from there. I suspect that because of the drip line that Main "A" was (is) originally a counterflow main and Main "B" because it has a return pipe, was (is) a parallel flow main. It's fairly common to have a steam system which has steam mains of each type.  
        As others have mentioned it would be a good idea to get Dan’s book titled “The Lost Art of Steam Heating” which is available in the Shop section of this website.
    Here’s a link to it:
    It’s easy reading and written so the homeowner new to steam can understand it and having it, we can then refer you to pages in the book that will answer the question you have far better than we could.
    - Rod
    This post was edited by an admin on April 8, 2013 2:21 PM.
  • gypsy gypsy @ 5:37 PM
    Contact this user

    Type of mains

    I have (had?) 2 counterflow mains.  Main B has its lowest point at the boiler with about a 30' run and a return on about the last 3 feet at the boiler end.  Main A has no return on a 12' run with its lowest part tied with- at the boiler and that dip you can see in the pic right after the first rad pipe splits off.  That drip pipe as well as the piping in yellow, the return connection above the water line on main B, and the two vents are new.  There are/were no other vents on the pipes.

    Thank you for the short circuiting explanation!  i get it now.

    (getting the book!)
    This post was edited by an admin on April 8, 2013 5:41 PM.
  • Rod Rod @ 6:54 PM
    Contact this user

    Counterflow Boiler Piping

    Hi- Knowing that both mains are counterflow helps clear things up.  The vent on Main “B” and the piping made me think that it was a Dry Return rather than a drip.  As I see it this is what you need.
    Drip Lines
    1.  Neither vents “A” or “B” are necessary (or do any good) and should be removed.  
    2. The drip lines from both Main “A” and Main “B” need to have enough slope so they drain easily.  No other lines should be connected into them.
    3. The drip lines from Main “A” and    Main “B” shouldn’t connect until they are well below the boiler water line level.  ( See attached photos of a really nice dual main counterflow system done by Steve Gronski, a Rhode Island steam pro)
    4. Steam bearing pipes like boiler near piping and steam mains needs to be done in threaded black pipe. Driplines and Wet Return piping can be done in either black pipe or copper.    

    Main Vents - On a counterflow main, the main vent(s) should be located at the end of the main farthest from the boiler. (See attached diagram)   Large capacity main vents are necessary so that air is able to quickly evacuate from each steam main. If you can tell us the size and length of each main we can calculate how much venting you need for each main.

    Header Pipe - The header pipe’s function is to dry out the steam by separating the water from the steam.  The header pipe needs to be sloped very slightly towards the equalizer pipe so that water will drain away back to the boiler.  I agree with Jamie, on the pipe going from the header to Main “A”, the 90 degree elbow connecting it to the header needs to be changed as the way it is now has to be sucking up water into the main.  Rotating the header tee slightly and using a 45 degree elbow should fix this problem
    ( See the attached photos)

    Additional Boiler Riser- I can’t help but think that adding a second boiler exit riser would help the system a lot as  it would cut the exit velocity of the steam in half. Less velocity means less water is carried up with the steam. It should be fairly easy to add a second riser.

    Boiler Water - Are you familiar with skimming and was the boiler skimmed?
    "The Book" will be a big help to you. My copy has paid for itself many times over!
    As always, let us know if you have questions.
    - Rod                                 
  • gypsy gypsy @ 7:40 PM
    Contact this user

    great info

    Thank you very much for the information Rod.   Do you know why the plumber who installed the vents and and drip line on main A, and changed the one on B from copper to iron would have done so then?  I was told this needed to be done to help or stop the hammering and water getting into the pipes.  Im really confused as to why it was even done now.  Thanks in advance.

    Yes its been skimmed and a bottle of some white powder dumped in to break up any oil.

    Very neat how that boiler was piped. 
    This post was edited by an admin on April 9, 2013 1:57 AM.
  • Rod Rod @ 11:12 PM
    Contact this user


    I have no idea why it was done that way other than very few heating professionals really understand Steam Heating and especially piping counterflow systems. Properly piped driplines are necessary as in a counterflow system, the condensate drains towards the boiler, the purpose of the drip lines is to divert the returning water away before it drops into the steam stream rising from the boiler.  What the  possible reasoning for installing vents in that part of the system I don’t have a clue.

     Radiators-    Since we’ve discussed the boiler already  it may now be beneficial to take a look at the rest of your system.  On a one pipe system the valve on the steam pipe should be fully open and the radiator sloped slightly towards the steam pipe end.  The slope needs to be just enough to “encourage” the condensate that collects in the radiator to leave. Check the radiator slope using a carpenter’s bubble level.
     Radiator Vents- Since your steam mains don’t have main vents that means that the radiator vents have to vent both the steam mains and the radiator to which they are attached. To make of for the lack of main vents people quite often use very high capacity vents like the Heat Timer Vari Valve on the radiators. These large capacity vents produce a lot condensate (water) which can interfere with e the incoming steam and result in water hammer.  There is an old steam adage:
    “Vent your mains fast (large capacity vents) and your radiators slowly!” which in my experience seems pretty true.
    What are the make and model of the radiator vents you are now using?

    Water Hammer- Attached is an explanation of water hammer in steam systems.
    The following is a link to list of steam system problems and cures which has a good section on water hammer.  You can tell a lot from when it occurs in the steam cycle -
    - Rod
  • gypsy gypsy @ 1:04 AM
    Contact this user


    I think i still have a couple of the old ones, but the new ones they put in when they said the vents were causing the problems are vent-rite no. 1'.

    The hammer is mostly at the beginning and towards the middle of the cycles, though the colder it is, the more it happens and if the water heater is trying to heat water at the same time the boiler is calling for lots of heat, it never stops.  (Right now its 75 in here, the thermostat is set for 62 and im awake listening to steam push its way through water coming up to a second floor radiator.)

    Thank you for posting this article!  I sit here and almost cry because of the shaking sometimes and everyone keeps telling me its not causing any problems.  
    This post was edited by an admin on April 16, 2013 3:21 PM.
  • vaporvac vaporvac @ 5:56 PM
    Contact this user

    Listen to the Pros here!

    Hi Gypsy,
    Don't know how I missed this plea for help!
    I'm another homeowner and female poster on here so welcome. There are a few of us lurking around, so don't feel lonely and don't ever feel silly for not understanding your system. There are so many different types and that's why this forum exists. Professionals use it, too.

    At this point of your saga I would suggest ditching your current plumber if he's not willing to make it right instead of charging you to make it worse. Charles Garrity is one of the most respected and knowledgeable professionals out there and you are VERY lucky if he's near you. I know how it feels to worry about doing it right, but there's no sense in throwing good money after bad. Steam heating works as a system and you must understand the whole thing before messing around with a single element. Your current plumber clearly doesn't.
    After you do a bit of reading, I'm sure you'll know more that most people you would call in. Take advantage of the positive here and get CG in for a look-see. He'll help ID what NEEDS to change immediately, and what might be good to change down the line so you can budget for it. There might even be some things you could learn to do yourself.

    Then you can learn some maintenance and look forward to the cold weather every year! For some, it's a bit addicting, but sometimes it's just nice when something works.
    Btw, I am NOT an expert and am constantly awed by the knowledge everyone has here, but I have learned a lot and you can, too.
  • Jamie Hall Jamie Hall @ 7:50 PM
    Contact this user

    I'll second that --

    If you can get Charles to come over and take a look (he'll charge for that, and it's worth every penny) that would be wonderful.  And I will vouch for his work: he installed the current boiler in my system, and did an excellent and thorough job, and really took the time to fully examine and understand the system.

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

    Hoffman Equipped System (all original except boiler), Weil-McClain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • gypsy gypsy @ 11:28 AM
    Contact this user

    Calling Mr. Garrity

    Thank you everyone!  Im going to call Charles Garrity.  
  • vaporvac vaporvac @ 1:43 PM
    Contact this user

    Post Pics!

    Great! I hope you'll  let us know the prognosis and post pics of the after. CTD
  • Charlie from wmass Charlie from wmass @ 10:44 PM
    Contact this user

    I am going to look

    on May 1. Thanks for the recommendation Guys
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
Post a Reply to this Thread