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Continuing water hammer issues

I have a one pipe, oil fired steam system with two main loops ( 'front loop' with 5 rads and 'back loop' with 3 rads) in my 1926 home. 3 or 4 years ago the old steam boiler cracked inside, sending the steam up the chimney. Not knowing much about steam boilers at the time and trying to delay having to replace the boiler, I allowed my well intentioned dad to add some sort of radiator crack sealer to the system. Not sure if that caused or contributed to the following issues. The sealer not surprisingly didn't work so I had the boiler replaced with a Peerless. Since then, I have had loud water hammer and water squirting out of one radiator on the 'back loop' (this rad had been a bit noisy even before the old boiler died). This rad starts off sounding normal, slight hissing of air leaving when heating up, them we start to hear gurgling water and water hammer and the rad fills up with water until it squirts out the steam valve. Not sure if the sealant collected somewhere in the back loop piping, this rad or if something else is going on. I believe the system was skimmed and all piping was done correctly on the install, Hartford loop etc., can put up pics. I have checked the pitch of the problematic rad, pitch of the pipes in the basement, changed the steam vents on all rads, insulated all pipes, swapped out main vents from Ventrites to Gorton 2s, flushed rusty water from the boiler- pretty much everything I have read about here or in Dan Holohan's book. Is it possible that this pipe or rad might be partially blocked, keeping water from draining? Can you scope or roto-root the pipe? Would love to get system fixed and balanced so we don't wake up to loud banging every morning at 5. I mostly try to use our wood stove now to heat due to the noise and higher oil costs. Any suggestions or qualified steam contractors in the Worcester, Ma area? Thanks for help and suggestions!


  • It Sounds Like

    The boiler is installed wrong, did it work quietly and evenly before you put the new boiler in?

    Thanks, Bob Gagnon
    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • ttime53ttime53 Member Posts: 13
    Water hammer issues, cont'd

    I had some (minimal) spraying of water from one or two rad steam valves before but it was not anywhere near as noisy. I have no issues with the front loop whatsoever. Will try to post some piping pics for you to look at and locate the installation guide for my comparison.
  • BobCBobC Member Posts: 4,457
    If I'm seeing it right

    Your hartford loop connection looks like it is at least a foot long - it is supposed to about 1 inch long. I can see where the wet returns all join together below the water line and then it comes up and joins the equalizer, that connection is supposed to be a close nipple not a foot long. That can cause all kinds of problems. The piping diagram is usually very specific about near boiler piping, compare the diagram with what you have.

    Post more pictures so we can see if there are any other areas that need addressing.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • ttime53ttime53 Member Posts: 13
    Water hammer issues, cont'd

    The three black pipes to the right in the right picture are the wet returns for (left to right) the back main loop, the front main loop (both vented) and the near boiler wet return. Would have loved to vent these back on 'antlers' but I don't have enough height. I believe they are about 6 inches above where the horizontal wet return pipes T into the horizontal pipe for the wet return.

    I had tried to turn the valve at the end of the Hartford loop to flush it out but it seemed to be clogged as nothing came out. Could it be filled with crud and not allow condensate back into the boiler water reserve? Can repost the pics (I retook them and seem better) if they are too dark.
  • ttime53ttime53 Member Posts: 13
    More pics

    Where can I find the diagram for piping? Manufacturers website? Not sure if I have the manual- I should but if I were a plumber who just piped something wrong the last thing I would want to do is leave a diagram of what I should have done...
  • Alternate main vent locations

    The main vents could be mounted on an antler threaded into a fitting on the vertical drop of each dry/wet return.

    The Hartford loop arrangement is wrong, but is probably not causing the spitting problems you describe. If the Hartford loop has too long a horizontal, there can be hammering in that pipe.

    The piping diagram should be on the manufacturers website (Peerless?) compare the arrangement of risers and header and their pipe sizes shown in the installation instructions with what you have. Posting the circumference of the various pipes will give us the size which is there. These instructions have been tested to produce dry steam, and not allow the boiler water to be flung up into the supplies, which seems to be happening with your system. Any installer who will not follow those instructions should be shown the door.--NBC
  • RDSTEAMRDSTEAM Member Posts: 134
    Noticed a few things.

    Looks like they used a reducing elbow for their equalizer and kept it horizontal rather than vertical. Although it should be a full size fitting turned vertically and then reduced a nipples worth down. The Hartford loop horizontal pipe looks like its about 2 feet long, that could cause banging towards the end of the cycle but not the spitting issue. I would suspect your problem lies somewhere in the main venting, causing high velocity steam pull water up the supply line.

    What type of pressure is the system running?
  • Double DDouble D Member Posts: 181
    Boiler piping is not optimal

    Could you post pictures of the front of the boiler and the connection to the 2 mains from the header? Do you have the model number of the boiler?
  • ttime53ttime53 Member Posts: 13
    More info

    Took some pics of the piping and model number. Also, should I be able to drain/flush the pipes using the valve at the end of the Hartford loop? When I turn it nothing comes out. I suppose the loop could either be clogged with hunk or maybe the valve or connection is bad. Any way to flush this?
  • ttime53ttime53 Member Posts: 13
    More info

    Forgot to mention the pressure is set to 0.5 psi.
  • Double DDouble D Member Posts: 181
    edited February 2014
    Still not looking optimal.

    Are you able to take another picture of the side with the energyguide sticker? Stand back far enough so I can see beyond the 90 with the reducer bushing in it. I still can't see where the 2 mains connect. Here is the installation manual for that boiler. Note how the riser feeding the main is going straight up not laying down. Compare the picture on page 6 with the piping around your boiler. I will also attach a boiler piping diagram for multiple mains and a write up on Hartford loops. Replace the boiler drains with full port ball valves it will make flushing much easier. 

    What you should know about Hartford loops.
  • ttime53ttime53 Member Posts: 13
    Piping from boiler

    I have a pic of the near boiler piping. Can see it is not like the diagram. Anyone know of a good contractor in the Shrewsbury/Worcester area if I have to have this redone? Should I contact the previous installer (through my oil company) to come fix this?
  • Jamie HallJamie Hall Member Posts: 6,708
    Well, it's different


    If you can't find anyone closer, try Charles Garrity (under Find a Contractor in Lee, MA).  I know he works that far east, and he's one of the best in this area.

    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
  • ttime53ttime53 Member Posts: 13
    edited February 2014

    The equalizer is on the left back side of the boiler (shown in one of the pictures). I know the Hartford loop is not connected to this via a close nipple- but piped in across the width of the boiler behind it. Should I try to call the installer to fix this for free or hire somebody who knows more? Also, should the main steam pipe go up then back down and then up again before going into the mains (as in the diagram)? What does that bend do?
  • vaporvacvaporvac Member Posts: 1,512
    edited February 2014
    Drop header

    Hi. That's called a dropped header and is the optimal piping for separating condensate and wet steam out of the header before it gets into the mains. Dry steam is the aim and dropped header is one of the best ways to achieve it, especially when there is little head room and/or a new boiler with smaller steam chest. In my own recent install it was the ONLY recommended manner of piping. Do a search for "drop header" on THe Wall and you'll find some great posts.

    I've read that anything other than a close nipple on the Hartford Loop can cause water hammer among other issues.
    Two-pipe Trane vaporvacuum system; 1466 edr
    Twinned, staged Slantfin TR50s piped into 4" header with Riello G400 burners; 240K lead, 200K lag Btus. Controlled by Taco Relay and Honeywell RTH6580WF
  • ttime53ttime53 Member Posts: 13
    edited February 2014
    Questions to ask

    I have someone from my oil company (who installed the boiler) coming out next week to look at my system. Going to mention no close nipple on the Hartford loop, mud leg clogged, no drop header, full port ball valve for mud leg (should the valve come straight off the mud leg or be after a 90? I would think coming straight off would be easier to clean but it is after a 90 elbow.) What else should I point out and ask about? Should I also get another independent opinion? Anyone recommend someone in the Shrewsbury/Worcester area?
  • vaporvacvaporvac Member Posts: 1,512

    charlie from Wmass may service your area. he's one of the best .
    Two-pipe Trane vaporvacuum system; 1466 edr
    Twinned, staged Slantfin TR50s piped into 4" header with Riello G400 burners; 240K lead, 200K lag Btus. Controlled by Taco Relay and Honeywell RTH6580WF
  • ttime53ttime53 Member Posts: 13
    Maybe like this...

    From what I've been hearing, should my system be repiped like this? I had a bit of time when coloring with my daughter... ;)
  • nicholas bonham-carternicholas bonham-carter Member Posts: 6,540
    Repiping a gurgling system boiler

    Using 2 risers might be better, and cheaper, because you may use 2 inch pipe instead of 3 inch.

    Just make sure they are both on the other side of the supply/header connection from the equalizer.--NBC
  • ttime53ttime53 Member Posts: 13

    Should the cleanout valve come straight off the mud leg or bend at 90 degrees first? Currently it bends. How is the mud leg best cleaned?
  • Double DDouble D Member Posts: 181
    edited March 2014
    Down when you can.

    So long as you can fit something under it to catch the mud, pointing down would be easier to control. There's always a chance it can plug no matter which way you point it but regular blow downs should prevent that from happening. Avoid using reducing bushings especially on a horizontal run. Use a full size reducing 90.
  • ttime53ttime53 Member Posts: 13
    Mud leg

    Leading away from the boiler, each successive wet return that connects to the mud leg reduces in diameter. Is this normal?
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