Water hammer

Discussion in 'Pumps and Tanks Well Forum & Blog' started by JoeyH, May 6, 2012.

  1. JoeyH

    JoeyH Learning as I go

    Messages:
    19
    Location:
    Bradenton, Fl
    Water hammer
    When my well pump shuts off, a bang sound(water hammer) is heard, I had followed the instructions that I have read online, a few times, and water hammer still happens when pump shuts off, I have a
    Well x trol wx202 pressure tank, I don't know how deep nor what type of pump I have, I have set pressure switch to cut in at 30lbs and cut out at 50lbs as per label inside cover, I have also shut off pump, emptied pressure tank, set pressure inside tank 2 pounds below cut in pressure, any sudjestions will be greatly appreciated, thank you in advance
  2. valveman

    valveman Moderator Staff Member

    Messages:
    4,383
    Location:
    Lubbock, Texas
    You probably have a check valve with the spring broken or the check valve is dragging. When the pump shuts off, the spring is supposed to close the check before the water direction reverses. If the spring is broken, the check only closes after the water reverses which causes a water hammer.
  3. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    3,838
    Location:
    NW Ontario, Canada
    Assuming a submersible in the well, the line should always be under pressure so under normal circumstances there should be very little flow reversal. If there is no checkvalve in the pump or it's broken and there is another checkvalve to compensate, that might explain the hammer.
  4. valveman

    valveman Moderator Staff Member

    Messages:
    4,383
    Location:
    Lubbock, Texas
    A second check valve or a check valve in the wrong place will cause water hammer on pump start. Water hammer on pump stop is from a check valve not closing until the flow reverses.
  5. JoeyH

    JoeyH Learning as I go

    Messages:
    19
    Location:
    Bradenton, Fl
    I just got up and shut off pump, tonight was my sprinkler night, the water hammer woke me up, I now belief that the water hammer is happening at both cut in and cut out, I think that at this time I need to pull the pump up from the well, find the check valve or valves and replace them, I have never done this type of work, is it very involved? Should I get proffecianal to do it?, I believe the pump is down in well, I don't know how deep, thank you for all of your advice and sudjestions, I do have a better understanding so far, thank you.
  6. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    3,838
    Location:
    NW Ontario, Canada
    If you are prepared to go that far, take it a step further and install a Cycle Stop Valve. The CSV will soften both the start and the stop as well as reduce the amount of cycling.
  7. JoeyH

    JoeyH Learning as I go

    Messages:
    19
    Location:
    Bradenton, Fl
    I just verified that water hammer is occurring at both cut in and cut out, this is the first time that it happens since I first noticed the water hammer at cut out, could it have been something that I did while checking pressure in tank? When I checked pressure this morning it was at 30lbs, I lowered it to about 26lbs, cut in hammer is stronger then cut out
  8. JoeyH

    JoeyH Learning as I go

    Messages:
    19
    Location:
    Bradenton, Fl
    I'm watching my sprinklers and water pressure coming out, is never been constant it varies quite a bit,
    I'm trying to put out as much info as I can, for better diagnostic, thanks again for your help
    Last edited: May 8, 2012
  9. JoeyH

    JoeyH Learning as I go

    Messages:
    19
    Location:
    Bradenton, Fl
    I have been digging to find the well pump, while running sprinkler system, and noticed that I no longer heard the water hammer, when I checked I found that pump was constantly running and pressure in tank would not make it to 50lbs the cut out pressure, ????????,
  10. JoeyH

    JoeyH Learning as I go

    Messages:
    19
    Location:
    Bradenton, Fl
    Upon further review, pump is back to cycling properly when sprinkler zone changed, it might be that previous zone lets out high volume of water, that's a whole other matter that may have to be addressed in the future
  11. JoeyH

    JoeyH Learning as I go

    Messages:
    19
    Location:
    Bradenton, Fl
    This well pump system was installed 1990, it has worked fine to this day, other then water hammer at cut out about one month or maybe longer, now that water hammer also happens on cut in, I don't know if it's time to have a pro pull out submersible pump to replace check valve or valves, my questions are.

    1. Can I install a check valve without having pump pulled out?
    2. Do I have any other options?
    3. What else can be causing a water hammer?

    I rather not pull pump out, due to work involved and cost,
    If I do have to pull pump out of well, should I have it replaced
    because it is 22 years old?
  12. valveman

    valveman Moderator Staff Member

    Messages:
    4,383
    Location:
    Lubbock, Texas
    If water hammer is also happening on pump start, then you must have a second check valve somewhere, probably before the pressure tank. Remove the above ground check valve and the problem will most likely go away.
  13. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    3,838
    Location:
    NW Ontario, Canada
    Adding more checkvalves is not the way to go. Multiple checkvalves was probably what caused the problem in the first place. It's not a more-is-better thing.

    The problem now though, is the bottom checkvalve may have failed because of the top one and now the top one is starting to fail because of a failed bottom one. You can try removing the top one and see if the bottom one holds. If it doesn't, you will need to pull the pump.

    As for how many years you have left in a 22 year old pump, if I knew that I'd be playing in Vegas. Since we don't know anything about the well, it's hard to estimate what it would cost to lift the pump. A new pump might be cheaper than the labor to pull it a second time when it does finally kick the bucket.

    Having the pump run constantly is better than having it cycle on and off. Ideally, you should tweak the zones so that the pump doesn't cycle.
  14. JoeyH

    JoeyH Learning as I go

    Messages:
    19
    Location:
    Bradenton, Fl
    Thank you both Lligetfa and Valveman, I've been inquiring about well pump removal, the way I see it is to pull it out, and put in a new one get rid of the old galvanized pipes and used 160 psi polyethylene piping with ONE new check valve, at this time I don't know how deep the well is, or how hard it would be to remove old pipes and well pump without a tripod, the polyethylene seems to be an easier way of repairing and removal in the future if I need to do this again.
    I have not fixed my issue with the water hammer, but I have learned a lot about well pump system thanks to all of you and your replies.

    Thank you very much
  15. JoeyH

    JoeyH Learning as I go

    Messages:
    19
    Location:
    Bradenton, Fl
    Found horizontal check valve, after much digging, I have not replaced it yet, I guess that I have to cut PVC pipe on one side to unscrew it and replace it, any sudjestions on best coupling to reattach, since pipes have no movement to insert a regular coupling.
    I have also noticed that water hammer is different when different zones are operating zone #1 light hammer on cut out, zone #2 pump will not cut off at all the whole time it's in use, zones#3 and#4 hammer in stronger and it happens on both cut in and cut out, how bad of a situation am I facing?
    Last edited: May 25, 2012
  16. valveman

    valveman Moderator Staff Member

    Messages:
    4,383
    Location:
    Lubbock, Texas
    You still don’t understand. You need to remove that check valve, not replace it. Just put a union or a telescoping repair unit in if you can move the pipe.

    Now to the reason your check valves are failing…. the pump is cycling on and off while you are irrigating, except for that one properly sized zone. When the pump cycles on and off, the check valve(s) are slamming open and closed repeatedly, until they fail. Cycling on and off is also causing abuse to everything else in the system. The water hammer from the failed check valves is just the first thing to surface. The pump will be the next thing to fail.

    You either need to size all your zones like zone #2, so that the pump stays running, or install a Cycle Stop Valve to make the pump match the zones.
  17. JoeyH

    JoeyH Learning as I go

    Messages:
    19
    Location:
    Bradenton, Fl
    thanks Valveman, I did not see your reply till now, my Local sprinkler store, suggested that I raise the cut in pressure to 35lbs, and that stopped the cut in water hammer, I did set the cut out pressures higher, and it did stop pump from cycling, tank pressure would not go hig, so ok, I'm going to remove Horizontal check valve, (I made the mistake and typed Vertical on last message), and if cycling does continue, I will install CSV, hopefully by removing check valve the hammer will stop, I will let you know either way.
    Thanks again
    Last edited: May 25, 2012
  18. traveller

    traveller Member

    Messages:
    44
    Location:
    British Columbia
    Just out of curiousity, how far is your pressure switch from your bladder tank?
  19. JoeyH

    JoeyH Learning as I go

    Messages:
    19
    Location:
    Bradenton, Fl
    About 24 inches of pipe.
  20. JoeyH

    JoeyH Learning as I go

    Messages:
    19
    Location:
    Bradenton, Fl
    I removed check valve, spring was broken and it was faulty, I replaced it with telescopic coupling, after I waited an hour for PVC glue to set, I turned pump on, no water hammer is heard when on nor off, that resolved, BUT, now after pressure tank fills, water is running out of it, all valves are closed and irrigation system is turned off, I can,t see anywhere that water might be leaking, I believe that it is going back down to well.....???????

    Pump comes on till tank is full and shuts off properly, but it is now continually cycling, system was turned on before check valve was removed, and it was holding water in pressure tank, all that I did prior to removing check valve was to turn off pump switch.
    Last edited: May 27, 2012
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