Water Hammer Arrestor

Pin

I have a one-pipe steam system and experiencing slight water hammer issue towards the end of the supply line where the risers are. An architect friend said that maybe I can install water hammer arrestor, which is a shock absorber, to solve the water hammer. I want to see what you guys think of this.



If the above isn't suitable, is there any thing I can install on the pipe to prevent the shock waves from the water hammer in basement to go up the riser. Maybe like a hard rubber ring securely fastened at the end of the pipes? Will fiberglass insulation also act as shock absorbers if I install them?



I have done a lot of work on the pipes already and made sure the pitch is at least 1 inch per 20 feet and all the radiators pitching the right way, but the noise is still there although not as bad as before.

Paul Fredricks_3

Maybe I'm wrong

But a water hammer arrestor is for domestic hot water. If you have a steam hammer there must be a reason. Possibly a pipe that's not pitched correctly or is sagging in the middle. There are a lot of possible reasons that would need to be taken care of.

Pin

I have checked

every inch of the steam pipes in the entire house and the pitch is correct and no sagging.



My theory is that what I am hearing in the pipe is probably not water hammer but rather the expansion or slight bending movement of pipes as it heats up.

Paul Fredricks_3

Could be

Steam hammer has a very sharp clanging bang. Expansion is a little duller in sound. Make sure the pipe has room to move through the hangers. Make sure that where the pipes go up through the floor that it isn't tight against the wood. Try to zero in on the source of the sound if those remedies don't work.

Pin

I have done all of the above

And know which pipe has the sound, but can not identify anything wrong with that pipe. The pitch is right, no sagging, not touching anything.



The sound is very soft and dull. I've given up trying to eliminate the sound, so what I want to do is to prevent the sound waves from traveling up the pipes to the upstair apartments by using some kind of shock absorbers, if there are such a thing.

Paul Fredricks_3

well

I can't imagine anything that could go in the pipe that wouldn't be a collection point for water and debris. Maybe one of the brain trust here might have an idea.

Jamie Hall

Water hammer arrestor

those things are made for water pipes, not steam pipes.  They won't take steam temperatures, and they won't take care of a water hammer in steam.  Forget it.



If it really is a hammer -- and as Paul said, a water hammer in steam is a very definite (and unforgettable) noise, as though someone is literally banging on the pipe -- the only solution is to find out where there is water collecting which can be pushed around by the steam.  As to pipe pitch, 1 inch in 20 feet is the absolute minimum pitch for parallel flow mains, and can be used for runouts to first floor radiators.  Counterflow mains need more -- no less than 1 inch in 10 feet -- and runouts to risers, such as to a second floor radiator -- need to be a pipe size larger than otherwise, and pitched a half inch per foot, unless they are dripped.  Another common source of one pipe steam hammering is a partly closed valve on a radiator.  They have to be either open or closed -- nothing in between.



Paul also noted that it may be expansion.  It may very well be expansion.  Make sure that the pipes are clear of all floor or wall openings -- a minimum of an eighth inch all around -- both when hot and when cold.  Sometimes expansion problems can be reduced by slipping a shim of some slippery plastic in, but choose something which can take the temperature.

Pin

The sound I hear in the pipe

does not seem like its water hammer but rather the expansion of the pipe. So it is a light clicking sound instead of a bang on the pipe.



If I were to install fiberglass insulation, will it act as a shock absorber to prevent the risers from hearing the little clicks?

Jamie Hall

Sadly,

probably not.  The sound is transmitted with astonishing effectiveness right through the pipe!  Expansion noises can be very difficult to get rid of.  As I think I mentioned earlier, the only sure cure is to make sure that there is clearance between the pipes and any floors or partitions they go through -- and even that may not do it.  Radiators click as they warm up...  good luck!

Paul Fredricks_3

Just a thought.

Have you checked the wet returns to see if they are clear? If not, condensate will back up into the mains and you'll get a steam hammer a ways into the heating cycle.

w2hp

Brand new boiler-never water hammer-now it terrible

Hi. I've got a 1927 steam single main heated home. Single steam pipe supply without a cold water return. Just took my 33 year old Utica out. Installed a Weil-McLain PEG-40 gas steam. Makes much steam. First time ever seeing the pressure gauge going up to 2 to 3 lbs. Utica at full steam never showed any reading. Boiler presure switch shuts down heater and then restarts as thermostat isnt not satisfied. Water banging resumes. Large loud hammer banging. My air vents are failing. Installing new units at failure. Installer (plumber) added a new cold water return on long feeder section of main into cold water of boiler return. Still banging. Very loud water hammer... My gas supplier PSEG sent a repairman and he said boiler is making too much steam for system. You need to lower output of boiler. Again, NEVER had water hammer before even with the 1927 5 section coal unit. Opened up main and saw no water inside. Pitch is about 1 1/2in every 10 ft. New air vents at both ends of main. Most upright radiators have new vents, but they dont hammer. Its the cast iron slant fin baseboards that hammer worst and even displace the outer covers of the enclosure as they move so much. They are secure again. The plumber doesnt want to return my cell calls. He has visited me 7 times since install. Last time I paid a huge copper piping bill plus 2 mechanics fees for the cold water return. Weil McLain's tech help line tells me the boiler functions perfectly. I believe them. They tell me I cannot lower output of boiler. Its not the boilers issue. Plumber tells me he just replaced my boiler. Pipes are my problem. Issue going on since Sept heating season. Banging keeps up up at night. Its that loud. Any suggestions. Very frustrated Peter

Paul Fredricks_3

Sounds like you need a pro

Someone who really knows steam.



I wonder if the pipes pitch was affected when the boiler was changed. They should pitch uphill as they move away from the boiler. And the pressure may be set too high. If you have a pressuretrol, it needs to be set as low as possible.



Use the "Find a Professional" link at the top of the page. It will probably be the best way to find out what's wrong, and what else may be wrong.

Paul Fredricks_3

And

Posting pictures would be great too.

nicholas bonham-carter

banging new boiler

better to start a new thread on this here, so it will get the attention it needs, and remember that pictures of your boiler piping will assist us in pinpointing the cause of your troubles.

why not get a 2nd opinion from a real steam man found with "find a professional" above.

first you need to compare the piping installed with the mfg's requirements in the manual-were they followed without deviation?those near boiler supply and return pipes are the installers responsabilities-not yours. 

check your pressure with a good low-pressure gauge [gaugestore.com, 0-3 psi] make sure it is as low as possible below 1.5 psi max--8 ounces even better.

get a copy of the steam books from the shop here, and be able to understand what makes steam so wonderful, when it is correctly installed!!--nbc

ttekushan_3

what NBC said

about starting a new thread and the boiler water is probably contaminated from the installation. And about that installation. We need pictures. In a new thread. We'd be glad to help.



-Terry