New boiler installed but with pretty bad water hammer, please help
Hey everyone, I will try to keep this short and apologize in advance for not knowing the correct terminology when applicable. We recently had a new boiler installed but about a week in, we noticed some loud clanging noises coming all the way up from the basement, and so we had a separate boiler guy come in to look over the installation job and identify the causes of the water hammer (luckily we brought in the second boiler guy under the pretense that he would work on some burst pipes that occurred elsewhere in the house, so whatever he would charge for inspecting our system would be covered under the insurance claim for the burst pipes.)
Anyway, the second guy seemed way more knowledgeable and pointed out a handful of things about the newly installed boiler that's causing the water hammer,
- The pipes on either side of the tee (yellow) should have been longer, especially pipe 1 (green, so that the rest of the pipes leading off from it would be routed to the other hole in the boiler (dashed line)
- The overhead pipe (circled in red) is pitched incorrectly, slanting downward towards the big elbow
- The original boiler installation guys did not skim the boiler, the second and more knowledgeable guy said it should have been done once after the initial installation with vinegar and then a second time at least a week after the boiler had been in operation
So I have a couple of questions here because I need to get on the phone with and probably do battle with the original boiler guys to correct as much of the above points as possible with minimal charge, which of these three issues contributes most to the water hammer we're hearing? As to the first issue, if the first issue contributes a lot to the water hammer, would it be enough to replace pipe 1 with a longer pipe to reroute the piping to the second hole, or do we need to lengthen pipe 2 as well?
Anyway, I plan on getting back to the second and more knowledgeable guy with these same questions but in the meantime, I thought I would share this entire issue over the internet for more unbiased opinions. I'm kind of hoping most of the water hammer will go away if we just ask the original guys to skim the boiler since that seems a lot less labor intensive than redoing pipe work.
Thanks for reading
Comments
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They need to add using the plugged tapping in the boiler to make a second riser to the header if your boiler install manual calls for it with your boiler check the manual
The pipe pitching down to the big elbow doesn't look like a problem but could be. You not going to be able to pitch that the way it is piped now.
The pipes on either side of the tee are ok
You need to skim the boiler regardless. Use Arm & hammer washing soda. Find out how much water the boiler holds and use 1 lb/50 gallons of boiler water.
What I would do is add the other rise if required. and skim the boiler. If it continues to hammer because of the red pipe install a tee with a 3/4" branch looking down as close to the big elbow as possible and pipe that branch into the boiler below the boiler water line
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What model is your boiler? The output is what determines how many risers you need.
The more knowledgeable guy said to use vinegar? Really? I wouldn't let that guy near my boiler. Cast iron odesn't like acid at all, and, while vinegar might be safe in the kitchen, acetic acid vapor in your boiler room can do a number on your mucous membranes and your eyes. Skim it with washing soda like Ed says. You should be able to find it at your grocery store if it's not already in your laundry room, but you can also find it at your pool supply store sold as soda ash. Same thing: Sodium Carbonate (Na₂CO₃). Not to be confused with Sodium Bicarbonate (NaHCO₃) or baking soda.
Just another DIYer | King of Prussia, PA
1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-240 -
If run off header is pitching down from head to big elbow, Maybe just take supply pipe off boiler a little higher say 5" or so and make a little drop header which would allow you to lower the header a bit. Little shorter nipple on equalizer to make up difference. Also add 2nd supply pipe if manual requires at same time. This would correct slope pretty readily. It would have been bit better to use reducing 90 off header rather than larger 90 and bushing to feed the main. Just .02 worth. Pretty simple rework. Then skim boiler.
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Check the boiler manual to see the minimum pipe sizes required by the manufacturer. Your header may be undersized; the vertical pipe above the big elbow is a lot larger than the pipe that feeds it.
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Bburd0 -
I'm more service and don't know much about steam piping without the book in front of me, but I think the coupling, union, and bushing need to go. That's the hammer. The union should be on the rise but they didn't have the height. IDK if riser height is correct. Drop header should've been done. The manual knows if the second riser is needed. I believe some of the steam pros use both regardless.
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Hey guys, I appreciate all the help so far, I just want to share quickly that I found a piping kit that's supposed to go with this exact model of boiler, and what they installed looks identical to what's suggested in this diagram from the manufacturer. So it's making me question a lot of the second guy's criticisms about the boiler installation job. That and one of the above comments saying that the suggestion to skim the boiler with vinegar was dead wrong. I'm at a loss here honestly 😵
I shut the boiler off just now and when it cools down tonight, I'll try to take some video or audio of the water hammer occurring to see if that might narrow down the cause - if I can even upload those files somehow onto the forum, I'm not even sure.
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There are several improvements that can be made and questions that can be asked.
That said, the most obvious cause of your water hammer and surging is dirty water. Any new boiler and its piping must be cleaned properly and the water line skimmed.
You should have the original installer return and finish the job, which should include this cleaning. If he balks at the request, direct him to the manufacturer's installation manual which outlines the procedure and its requirement.
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What the diagram of the piping kit is NOT indicating is pipe sizes. The piping must be large enough to keep the velocity low so that water is not drawn up into the system with the steam.
Just because your piping looks similar in configuration does not mean that your pipe sizes are sufficient. In fact, looking at the size of the existing pipes, I’d say that the new piping is way undersized.
Bob Boan
You can choose to do what you want, but you cannot choose the consequences.
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If the pipe toward the flange and ell really pitches significantly toward the ell that will hold water and be a problem. needing skimming will cause many problems. what happens above the flange, that could be holding water if the old header is still up there and not dripped.
if the pipe sizes are at least the manual size and the manual allows a single riser that part should be ok.
Seems like it is the installer's problem to fix it, don't see why it would cost more to make it work.
I don't think the vinegar is a great idea to skim but it wouldn't hurt as long as you flush it out after. the way the second guy suggests is better but may be overkill so i think they do more or less know what they are doing.
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That shouldn't be a problem, the union won't hold and significant water, the bushing is in a direction that the condensate can drain down the riser. It may be too small, have to look at the manual, but it isn't inherently a problem.
It could have been eliminated by using the flange for its intended purpose but it shouldn't hurt anything
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The riser out of the boiler should probably be the size of the tapping in the top of the boiler, it shouldn't be bushed down. I cant see if it is in your picture.
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