Water Hammer & Water Hammer Arrester location

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by amkazen, Oct 9, 2011.

  1. amkazen

    amkazen New Member

    Messages:
    26
    Location:
    New Mexico
    Hi,

    I have a question about water hammer and their location.

    I live in a house I built myself 10 years ago in a very remote location. And, the remoteness causes issues with contractors as they do not like to drive to my house. I had a difficult time getting contractors to bid on my house 10 - 11 yrs ago, and since then it has been very difficult to get folks to come and work on things. So, I tend to do most everything myself.

    One of the issues I have is my plumbing, and the issues started with the plumbing contractor I hired 11 yrs ago. I have slowly started correcting some of the plumbing issue with the 1 - 2 guys who initially came up her, but now will not due to the remoteness. They state they can do 2 - 3 jobs in the time it takes to come to my place, start work, realize they left something or forgot something, go get it, and then come back.

    My big issue now is water hammer that has been going on for years and is getting worse.

    We are on a well that pumps into a 3,000 gallon stainless steel storage tank outside the house. Then a 220v jet pump in the mechanical room in the house will turn on when the 80 gallon pressure tank requires water. The jet pump "sucks" the water out of the 3,000 gallon tank and fills the 80 gallon pressure tank with water under pressure. This is like a well pump that is connected straight to a pressure tank, without a storage tank between the well & pressure tankl. The well pump itself forcecs / supplie water under pressure, to the pressure tank. There is a one-way back-flow preventer valve on the water supply line into the house. Once the jet pump kicks / shuts off there is a TREMENDOUS water hammer...it is so loud and right now the lights have started to dim when the pump shuts off. It is getting worse.

    Where could I put a water hammer arrester to prevent this from occurring...immediately / right where the water enters the jet pump? I could put a tee and vaertical pipe right there.

    Before the backflow preventer, meaning before the water 1st passes thru the back-flow preventer?

    Or, just after the back-flow preventer, which would be about 10' feet and one 90 degree elbow before the jet pump?

    And, which specific water hammer arrester would you suggest? The water supply piping is 1" copper.

    And, hmmm...I am starting to think the water hammer 1st started after a back-flow preventer was installed.....the original plumber did not install one and that was one of the "fixes" on of the subsequent plumbers did. Hmmm...is it possible the back-flow preventer is the cause, whereas before the pressure would just force the water back thru the pipes into the 3,000 gallon storage tank? I just don't remember there being a water hammer issue when we 1st moved in. I never made this connection before. Do you think the back-flow preventer could be the cause and not allowing the pressure any place to go? If it is, I am thinking now the arrester should go immediately before the jet pump. Wow..memory after turning 50 is not like it used to be..LOL

    Thanks for the help.
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,811
    Location:
    Cave Creek, Arizona
    quote; This is like a well pump that is connected straight to a pressure tank, without a storage tank between the well & pressure tank.

    I am not sure what that means because you should have a pneumatic storage tank after the pump which stores the water under pressure. I am not sure what you mean by "pressure tank" and "storage tank", since they should be the SAME tank.
  3. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,225
    Location:
    Maine
    Water hammer arestors need to be installed as close to the device as possible, however, try removing the check valve first.
  4. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    4,050
    Location:
    NW Ontario, Canada
    The checkvalve should be placed between the storage tank and the inlet of the jet pump, emulating what a footvalve in the well would do. There is no way that the lights should dim when the pump shuts off. Something is amiss there. If the checkvalve is slamming shut, it is defective and needs to be replaced.

    Is the 80 gallon pressure tank a bladder type and have you tested it? How much pipe is there between the jet pump and the pressure tank?
  5. amkazen

    amkazen New Member

    Messages:
    26
    Location:
    New Mexico
    ".....I am not sure what that means because you should have a pneumatic storage tank after the pump which stores the water under pressure. I am not sure what you mean by "pressure tank" and "storage tank", since they should be the SAME tank....."

    A pneumatic storage tank? A tank with hydraulics?

    And, yes, a pressure tank & a storage tank is one & the same.....most folks on a well only have a pressure tank...that is their sole source of water storage: 80 galls, 40 gallons, etc. whatever size tank they bought. I did not want to be limited to 40 or 80 galls. If the well pump goes out you have no water, except for what your pressure tank has stored, what is in the toilets, etc. And, try getting a well guy to fix your pump quickly. So, we went with a large 3,000 gallon storage tank so if our well pump ever went out we did not have to scramble around to get a well guy out.....we would be able to call and wait, and not panic that we did not have any water. I was just trying to describe what I had as a lot of people do not understand the need for a jet pump..they do not know the pressure tank needs to have water "forced" into it, which is normally done by the well pump.

    Ok, so it is best to put the arrester as close as possible so that means right where the water goes into the jet pump.

    Now, I just need to find a arrester...Do any of you have any experience with any...such as those that seem to have more problems than others? Is there a particular size or pressure or rationg or whatever since it is for the pressure coming off a jet pump?

    Thanks,
  6. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,225
    Location:
    Maine
    You don't need an arrester, you need to get rid of the check valve
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,129
    Location:
    New England
    You should not need a hammer arrestor in your system if the pressure tank is functioning properly. The check valve should be before the pump. Water hammer occurs when a fast moving stream of water gets shut off by a valve. The arrestor provides a cushion to slow that water down and disipate the water's inertia. You might need them at places like the washing machine, ice maker, and some types of quick acting valves, but not on the jet pump. The pressure tank should be able to perform that function and is the equivalent of a big hammer arrestor in and of itself. You need to check the static pressure in the bladder of the pressure tank. Is your jet pump set up with a typical hi/low pressure switch? The pressure tank should be set 1-2# below the low-pressure turn-on pressure of the jet pump's pressure switch. This can only be checked when there's no water pressure (i.e., the tank is essentially drained and a valve is open with the pump off).
  8. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    4,050
    Location:
    NW Ontario, Canada
    No. A water hammer arrestor works on a cushion of air under pressure. It doesn't belong on the suction side of a pump.
  9. amkazen

    amkazen New Member

    Messages:
    26
    Location:
    New Mexico
    Get rid of the check valve? I was told by a licensed plumber a check valve is needed to prevent the water from flowing back into the tank, and hence it was installed. This plumber told me the original plumber who plumbed the house when we built it shoudl have known this and failed plumbing 101. And, this "2nd" plumber is not the only plumber who has told me this...so, now I have a plumber saying a check valve is not needed. So, a new question: is the check valve needed?

    The check valve is before the jet pump. Here is the complete order of equipment: well pump, then 3,000 gallon storage tank, then the check valve, then the jet pump, then the 80 gallo pressure tank, then the house fixtures.

    Since water hammer occurs when fast moving stream of water gets shut off. The jet pump is sucking water from the 3,000 gallon tank and then when the pump shuts off & stops sucking...BAM

    Ok, a water hammer arrester works on a cushion of air under pressure and does not belong on the suction side of a pump. Ok, so does the arrester go between the jet pump and the 80 gallon pressure tank? But, if a water hammer is not needed, then perhaps the 80 gallon pressure tank is bad. I have had to replace the smaller expansion tank connected to the indirect water heater once already, and had a plumber add a 2nd expansion tank to the lines coming of the radiant boiler....water hammer before, water hammer after...

    The static pressure of the 80 gallon tank has not been checked. Is there a guide ont his web site to explain how to do that?

    I do not know if the jet pump has a hi / low pressure switch. If it does, where should I set it?

    No water pressure.....so, unplug the jet pump so it cannot suck water, turn onthe bathtubs and run them until no water comes out...right? Is that how I get rid of the water pressure so I can then check the air pressure in the 80 gallon pressure tank? And, how do I know if the bladder is bad? Air up the bladder and wait for 24 hours to see if it loses pressure? Does that mean we go without water for 24 hrs or some time? ugh...

    Thanks. You guys are helping and I am sorry I am not getting this right away.
  10. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,129
    Location:
    New England
    IF you've drained the tank, then try to add air, if you have left a valve open, and the bladder is bad, you won't be able to increase the pressure, as all of that air will just leak out through the broken bladder and out the pipes to the open valve. Also, before you start any of that, the tank should sound hollow at the end where the air valve is...if it sounds like it's full of water, it probably is. Also, if you check the pressure before you drain it and water comes out the air valve, that's a sure sign the bladder tank is shot.
  11. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    4,050
    Location:
    NW Ontario, Canada
    Most people have a drain cock at the base of the pressure tank. That would be the right place to drain it.

    You should consider installing a Cycle Stop Valve. Not only will it cut down on pump cycling but it will also give you constant pressure plus it will soft stop the pump and soft close the checkvalve.
  12. amkazen

    amkazen New Member

    Messages:
    26
    Location:
    New Mexico
    Hi,

    I came back here to ask a question and noticed I never replied with the final solution to this water hammer issue. Nothing I did or any plumber did solved the issue until this past March. We had a well guy come out and he removed the jet pump from the system and put a submersible pump in the 3,000 gallon storage tank. Viola! No more water hammer. Thanks for all the help.
  13. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,811
    Location:
    Cave Creek, Arizona
    quote; I was told by a licensed plumber a check valve is needed to prevent the water from flowing back into the tank, and hence it was installed.

    You did NOT need to keep the water from flowing back into the tank. You had to keep the water from flowing back into the STORAGE tank, so the check valve should have been at the pump so the pressure tank could act as you water hammer arrestor.
  14. amkazen

    amkazen New Member

    Messages:
    26
    Location:
    New Mexico
    Uhh, I think the two older posts said the same thing you just said...keep the water from flowing back into the storage tank. And, that is where the check valve was installed. Anyway, as I said, I was just coming back to say the water hammer issue was resolved when the submersible pump was installed in the 3,000 gallon storage tank. Thanks for the help.
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