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  1. #1
    Join Date
    Jan 2014
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    Default Heavy Water Hammering at Cold Incoming Water pipe into Indirect Fired Hot Water Tank

    Hi Friends,
    I have two Hot Water Storage Tanks heated by Indirect Fire Method. Lately Cold water pipe going into Storage Tanks (Shown in Picture link) is banging very hard that i can hear that noise from two floor above 300 feet away. I have also attached MP3 file link on recording of actual noise. It appears that when cold water being filled to Storage Tank this pipe are banging because water seems to back flow heavily due to high pressure. My main cold water pipe pressure is 50 psi. Not sure what exact pressure at water tank level. When pipe hammers, if I open any of the hot water valve open at anywhere in house, it immediately stops hammering but it again starts after 5-10 minutes. It is doing more on late night when we are sleeping than during day time. May be because we use water which releases the pressure.

    Can someone please help me understand what could be causing this issue and what can I do to fix it permanently ?

    1) Picture of Indirect fired Hot Water Heater Storage Tank: https://app.box.com/s/2yixrskgxcvltlozkh9j
    2) MP3 Sound File Noise coming from Cold Water Pipe Shown in picture: https://app.box.com/s/2htd4crc8z4mlr23igz6

  2. #2
    Join Date
    Feb 2010
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    South*East
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    1,208

    Default Re: Heavy Water Hammering at Cold Incoming Water pipe into Indirect Fired Hot Water T

    Sounds like a bad pressure reducing valve. Not the one feeding the boiler but the one on the cold water feed to the tanks.
    John

  3. #3
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    Default Re: Heavy Water Hammering at Cold Incoming Water pipe into Indirect Fired Hot Water T

    You should have an expansion tank connected to the cold side at the WH's- you didn't mention if you do or not. This usually reduces or eliminates this problem, but you may also need a pressure regulator on that line (again at the WH and upstream of the expansion tank) to prevent backpressure and hammering. Also check that the cold piping is securely mounted but can expand and contract a bit freely too.

    Phil

  4. #4
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    Jan 2014
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    Default Re: Heavy Water Hammering at Cold Incoming Water pipe into Indirect Fired Hot Water T

    Quote Originally Posted by Mastercarpentry View Post
    You should have an expansion tank connected to the cold side at the WH's- you didn't mention if you do or not. This usually reduces or eliminates this problem, but you may also need a pressure regulator on that line (again at the WH and upstream of the expansion tank) to prevent back pressure and hammering. Also check that the cold piping is securely mounted but can expand and contract a bit freely too.

    Phil
    I agree with your judgement about Expansion tank. I do not have expansion tank on WH, I do have expansion tank on boiler though. What is puzzling me is why it is causing to only one tank and not the other and why after 7 years of operation and not before.

    Can you suggest me exact location where I can put Thermal expansion tank and how big. These tanks are 40 Gallon each for hot water. Do I need two or only one expansion tank ? Manufacture of tank do suggest to intall expansion tank but not sure why it was not installed by plumber.

    I do have backflow preventer shows in link I have provided. Per Manufacturer either Backflow preventer or pressure Reducing valve should be installed.

    Below is the real picture of setup of two Hot water Storage Tank using Indirect Fired, also 5 baseboard heat zone is feeded by the same boiler besides the hot water.

    https://app.box.com/s/9100wwmrrgt7z6wpfyt0
    https://app.box.com/s/q2xmc7tywm6xhpjk7i6s

  5. #5
    Join Date
    Jul 2010
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    SoCal
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    Default Re: Heavy Water Hammering at Cold Incoming Water pipe into Indirect Fired Hot Water T

    You can install it along the incoming cold water pipe.

    Also, I noticed that your pipe straps are not copper - change them to copper straps or wrap the pipes with tape (like electric tape) at the points of contact with the existing straps.

  6. #6
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    Jan 2008
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    Default Re: Heavy Water Hammering at Cold Incoming Water pipe into Indirect Fired Hot Water T

    Have you checked that the expansion tank at the boiler is OK? the diaphragms in these can fail and the air pressure in them will normally leak down very slowly too. If that same cold line feeds the boiler then that's likely the problem. Or perhaps the back-flow preventer isn't sealing well anymore.

    If it's worked well till now you shouldn't need anything additional, just find and fix whatever changed in the system that isn't working well anymore- that should fix it. I'd still like to see an expansion tank on that cold line- one before both tanks will do.

    Phil

  7. #7
    Join Date
    Dec 2013
    Location
    Montreal Canada
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    Default Re: Heavy Water Hammering at Cold Incoming Water pipe into Indirect Fired Hot Water T

    Lordofthering could you give us the temperatures when this happens and the temperature when it stops. You said that when you run hot water in any of the hot water fixture the noise stops.

  8. #8
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    Jan 2014
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    Default Re: Heavy Water Hammering at Cold Incoming Water pipe into Indirect Fired Hot Water T

    Quote Originally Posted by Mastercarpentry View Post
    Have you checked that the expansion tank at the boiler is OK? the diaphragms in these can fail and the air pressure in them will normally leak down very slowly too. If that same cold line feeds the boiler then that's likely the problem. Or perhaps the back-flow preventer isn't sealing well anymore.

    If it's worked well till now you shouldn't need anything additional, just find and fix whatever changed in the system that isn't working well anymore- that should fix it. I'd still like to see an expansion tank on that cold line- one before both tanks will do.

    Phil
    I have changed Expansion Tank on Boiler two weeks ago since older one was out of Air and I think inside Diaphragms was broken. I thought that was issue but after changing did not make difference.

    I am thinking it is Backflow preventer not doing job. Question what is causing issue ? Is it too high pressure in tank ? or Water is allowed to go back due to bad Backflow Preventer due to high pressure ?. Wouldn't be working of Backflow preventer is cause of issue because too much pressure in hot water tank being built and Backflow preventer is not letting pressure go above it so it is causing pipe to bang due to high pressue ?

  9. #9
    Join Date
    Jan 2014
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    6

    Default Re: Heavy Water Hammering at Cold Incoming Water pipe into Indirect Fired Hot Water T

    Quote Originally Posted by bill shack View Post
    Lordofthering could you give us the temperatures when this happens and the temperature when it stops. You said that when you run hot water in any of the hot water fixture the noise stops.
    Unfortunately I am not sure how to take temperature. If you can give me idea, I can try to provide you the result.

    Yes, If I open any hot water tap it will stop banging because (I believe) it is releasing pressure which is being built in hot water tank due to expansion and only way this pressure to get released is from hot water side of the tap since backflow in cold water side will not allow this pressure to go up anymore even it tries to which is causing pipe hammering.

    I am almost in agreement of putting expansion tank between Backflow preventer and Tank which should start absorbing the high pressure but not sure if that is only and right way of handling issue. Is there any other way of looking at from root cause ?

    Also, one thing to note that this is only happening when there is no activity of hot water being used in house. Generally early in the morning when Heat in house Kicks Off and No one is using bathroom or any other place for hot water.
    Last edited by lordofthering; 02-04-2014 at 09:44 PM.

  10. #10
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    Jan 2014
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    Default Re: Heavy Water Hammering at Cold Incoming Water pipe into Indirect Fired Hot Water T

    I have installed 4.4 Gallon Thermal Expansion tank between Shut off valve and Water Heater Tank. When i checked pressure at that point, it was 55 psi where as regular pressure in my house is 50 psi. I am assuming it is due to hot water pressure build up which will increase pressure.

    Here is the link with Expansion tank Installed on cold water side:

    https://app.box.com/s/2n88rwz2xtb89u32htew

    I will update the forum if issue is resolved.


    Any one can help me what should be the pressure for incoming cold water to Water Heater ?. Should it be same or close to house pressure or lower ?. Do I need to install pressure reducer ? or back-flow preventer which i have is OK ?
    Last edited by lordofthering; 02-09-2014 at 07:30 PM.

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