Check Valve Shutoff Loud

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by monty, Dec 9, 2013.

  1. monty

    monty New Member

    Messages:
    41
    Location:
    San Francisco
    Hi,

    We are having a problem that was isolated to our check valve at our cold water input to our hot water heater.

    Whenever we have a quick shutoff of water (toilet, sink, dishwasher, clothes washer etc...) the check valve has a thump/bang that is fairly noticeable. The biggest problem is this valve is right on the wall next to my child's bed - so he hears this thump or thump/thump that sounds like someone knocking on the wall - the wall is almost acting like a speaker and amplifying the sound. I am having my plumber look into it at the moment, but so far no solution has been determined.

    So since I have received such great help on this forum over the years I wanted to ask!

    Our hot water re-circulate loop connects to this same area as well, however it does have a proper expansion tank above this check valve. The current check valve is brass and sitting horizontally.

    I would love to find a different check valve that is silent - I will need to get the actual valve type spring or swing, size etc... figured out and will take a picture later today.
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,487
    Location:
    Cave Creek, Arizona
    You must be getting a "huge" cold water pressure drop when you open any faucet, so that the pressure in the expansion tank is "slamming" the valve closed, assuming it is open. Check your cold water pressure WHEN a faucet is running and also when everything is shut off.
  3. monty

    monty New Member

    Messages:
    41
    Location:
    San Francisco
    Update - Photo Enclosed

    The pressure is very stable. This is a brand new home - all modern fixtures, mostly pex tubing, and should be compliant with the applicable plumbing codes.

    I guess the local inspector insisted on this check valve - including the actual part number to use.

    Here is a photo I just took (it is a swing check valve). I would like to put in a spring check valve to see if that helps.

    The noise is not terrible - it just attenuates through the stucco wall in the background - right to the bedroom wall.

    IMAG0023.jpg
  4. Smooky

    Smooky Member

    Messages:
    596
    Location:
    NC
  5. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,487
    Location:
    Cave Creek, Arizona
    The thing is that it should NOT even happen in the first place so you should find out exactly WHY it is occurring, before you spend time and money eliminating the symptoms. "Pressure is stable" may be a subjective opinion, ( I had a gas unit yesterday that the pressure "looked proper" but was actually quite low), rather than fact. You will not know until someone actually does a proper test of the system.
    Last edited: Dec 10, 2013
  6. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    3,902
    Location:
    NW Ontario, Canada
    If the swing valve is part of a gravity recirc, a spring-loaded one will defeat the recirc.

    As was mentioned, you need to find and treat the cause, not the symptom.
  7. monty

    monty New Member

    Messages:
    41
    Location:
    San Francisco
    Thanks for the help...

    The picture is the 60psi cold water supply coming into the house from city water (coming in from the left) - the check valve is the first component in the chain at that point. The lower larger line feeds the water heater down and back to the left - the smaller copper line coming back in from the top of the photo is the recirculate hot water line - our recirculate is a pump based system, an expansion tank is just above the photo on this smaller copper line.

    The explanation to me was that it has nothing to do with the recirculate line itself - but the noise is from the quick shutoff of the various fixtures in the home (toilets, auto faucets, electronic shutoffs). These are fast shutoffs - and a small amplified hammer type effect is occurring.

    The sound isn't even very noticeable standing right in front of the check valve - it is more amplified on the other side of this wall (after passing through the stucco wall and into the stud bay on the other side).

    I have read a bunch of stories of these swing check valves having some noise - I just want something to be quieter to appease a 4 year old and his parents!!!
  8. monty

    monty New Member

    Messages:
    41
    Location:
    San Francisco
    Thank you for the help.

    Is it possible to have a small sound that we are just (too) sensitive to with this swing check valve? I think there is more sound because it is somehow right into a stucco wall - it is much more noticeable inside the home - I think the stud bay is acting like a speaker box...

    I have a pressure gage that I attach to various hose bibs while having faucets, toilets and other things turned on/off? What should I be looking for? Pressure up/down 1 psi/5psi/10psi?
  9. monty

    monty New Member

    Messages:
    41
    Location:
    San Francisco
    Thanks for the suggestion - in the description of this part I see the following (my emphasis added)

    "Series 600 Bronze Silent Check Valves efficiently perform all of the functions of a swing check or vertical lift check valve and at the same time operate silently to prevent the effects of water hammer."

    I kind of feel like this is my condition - and a solution then? Based on the other comments above I need to figure out why the hammer is occurring. Is that the consensus then?
  10. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,487
    Location:
    Cave Creek, Arizona
    IF you put the pressure gauge in the right location so it registers the cause of the sound, you may find that when it occurs the gauge needle goes to the maximum, regardless of what the gauge has as a high limit, for a millisecond or so. Your check valve is horizontal and the "flap" is on an angle, so it is normally CLOSED and can only create a sound if something opens it and then it bangs shut. In your description, there is NO flow to open it when you are using code water so it could not "close" to make the sound.
  11. monty

    monty New Member

    Messages:
    41
    Location:
    San Francisco
    Hi HJ,

    I am not understanding what you are saying above. Could you help me understand it better?

    The check valve is on the incoming city cold water service and precedes all cold water feeds into the house - the pipe then branches off and one line goes up to the cold water distribution throughout the house, another branch is the cold water feed to the hot water heater.

    The sound occurs only after cold water is supplied to a toilet, sink, clothes washer, or dishwasher - so the check valve would then be open while the fixture is on I think - when the fixture turns off (abruptly in this case) that is when the sound occurs. I can prevent the sound from happening by turning on a sink and leaving it running just as a toilet turns off. I believe the sudden shutoff and closing of this valve (no more cold water called for) is creating the sound.

    Note: I can post a bigger picture of all of the pipes if that would help. THANKS!!!
  12. Smooky

    Smooky Member

    Messages:
    596
    Location:
    NC
    Backing up and taking a photo to show the complete system might help. Generally this type of back flow preventer is used to isolate the hot water return water from the cold water distribution system. From your description it sounds like the swing check is just preventing water from backing up into the city supply. Swing checks are not usually acceptable to protect the source from contamination. Usually a dual spring check is used to protect the source for a house, when it comes in from the city supply. Location and type of back-flow preventer is important in preventing hot water from getting into the cold and vice versa.
  13. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,487
    Location:
    Cave Creek, Arizona
    Originally, you said the cold water goes down and to the water heater with the return coming from the top, which is correct since the check valve would ONLY be on the line to the water heater. Now you are saying that there is an additional connection which supplies the whole house after the check valve, (which does not show in your photo), which COULD cause the sound, because of the expansion tank, but which should also send hot water from the return line through the cold water system if it is actually connected that way.
  14. monty

    monty New Member

    Messages:
    41
    Location:
    San Francisco
    Well now I am not totally sure, looking at the pipes again, where the cold water supply to the house comes and goes. The valve is certainly on the cold supply the hot water heater...

    I have taken 2 more photos that show the side of the system with the valve and recirculate line. Hope it helps - Thanks again for the advice!

    waterheater2.jpg

    waterheater1.jpg

    Shown kind of stitched together - so the top photo is shot above the lower one...
  15. monty

    monty New Member

    Messages:
    41
    Location:
    San Francisco
    AFAIK there isn't one - as the water at the street in our location is 60psi.
  16. Smooky

    Smooky Member

    Messages:
    596
    Location:
    NC
    I do not think the swing check is any good in that location as the pipes are now Also the hot water return is mixing with the cold water. There should have been a tee in the cold water line before the swing check and that would have prevented hot from getting into the cold. I would change the swing check for a spring check. I would do away with the tee below the recirculating pump. As it is now instead of hot mixing with cold at the mixing valve, hot could be mixing with warm or even hot mixing with hot.
  17. DonL

    DonL Out of the Trades

    Messages:
    3,917
    Location:
    Houston, TX
    It is probably the tank making the noise and resonating.

    I am surprised that install is to code and was inspected. Very cool how they routed around the electrical outlet.

    I think that tank is to heavy to be hanging like that. Wait until it is waterlogged.


    But I am not a plumber.
    Last edited: Dec 13, 2013
  18. monty

    monty New Member

    Messages:
    41
    Location:
    San Francisco
    Thanks for the suggestion.

    After looking harder at the piping (me not being an expert by any measure...) it does appear that the cold water for the rest of the house is not branched off of this line at all, sorry for stating that in my other posts. So this is just the hot water supply section that I have photographed. Does that change things at all?

    I think the the pressure must drop on this cold water feed to the hot water heater slightly when the rest of the house fixtures are calling for cold water - then when the quick shutoff happens that swings this valve a bit? Causing the thump thump sound?

    With that in mind, and the other points made by others - any reason to not switch to a spring check valve? (Watts part LF601S Lead Free* cast copper silicon alloy Maxi-Flo Check Valves).
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