Question - Increased Water Pressure after Expansion Tank Replacement

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by MBridges, Dec 2, 2019.

  1. MBridges

    MBridges New Member

    Joined:
    Dec 2, 2019
    Location:
    Montgomery, AL
    Two weeks ago, I had to replace the expansion tank on my hot water heater. Ever since then, it seems like there is increased water pressure when I flush wither of the two toilets in the house. In the master, you can hear like a banging in the wall as you flush. In the other bathroom it sounds more loud with an abrupt stop once the tank is filled. I have not noticed significant water pressure or pulsating water from any of the faucets. This was not issue before the expansion tank was replaced.

    Is this normal? Is there something I can do to reduce the pressure or does this mean there is something wrong with the expansion tank?
     
  2. Reach4

    Reach4 Well-Known Member

    Joined:
    Sep 25, 2013
    Location:
    IL
    You can adjust the pressure switch to a lower range. After changing the pressure switch, you should adjust the air precharge in the pressure tank.

    What is your water pressure now?
     
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  4. MBridges

    MBridges New Member

    Joined:
    Dec 2, 2019
    Location:
    Montgomery, AL
    I have not checked it yet, but plan to do so this evening.
     
  5. mliu

    mliu Active Member

    Joined:
    Feb 7, 2007
    Location:
    Colorado
    What pressure switch are you referring to?
     
  6. mliu

    mliu Active Member

    Joined:
    Feb 7, 2007
    Location:
    Colorado
    OP:
    • Are you on a well or municipal water?
    • If municipal, do you have a Pressure Reducing Valve (PRV) installed?
    • Why did you have to replace your old expansion tank?
    • What was the pressure in your new expansion tank when you installed it? Did you adjust the precharge to match your normal water pressure? (Doubtful since you don't seem to know your water pressure.)
    • After replacing your expansion tank, did you open all valves you had closed to make the repair?
    Post a photo of your expansion tank set-up.
     
  7. MBridges

    MBridges New Member

    Joined:
    Dec 2, 2019
    Location:
    Montgomery, AL
    Thanks for responding. I am on city water. My old tank developed a tiny pin hole in the top and started spraying water. I do not have a pressure relieve valve. When I installed the new tank, I did not check the pressure which I believe my problem may be. Once the new tank was installed, I opened all valves that were closed. The new tank came pressurized at 40 psi. However, my water pressure usually runs 60-65 psi. Could that be the reason for my issues? If I need to add air to the tank, what is the process?
     
  8. mliu

    mliu Active Member

    Joined:
    Feb 7, 2007
    Location:
    Colorado
    The tank must be pressurized to match your water pressure. You can do this without removing the tank.

    If you have a shut-off valve in your cold water supply upstream of the expansion tank, shut it off. If not, shut off the house main. Open a hot water faucet on the same floor as your heater and leave it open to relieve all pressure in the water heater (and thus in your expansion tank). Now you can use a bicycle pump to increase raise the pressure in the tank to 65 psi. After that, shut off your faucets and open your valves.

    I'm not convinced this is your only problem. But you need to eliminate one possible culprit at a time, and we know this is a problem.
     
  9. LLigetfa

    LLigetfa DIYer, not in the trades

    Joined:
    Feb 6, 2011
    Occupation:
    Semi-Retired
    Location:
    NW Ontario, Canada
    Every water heater should have a TPR (Temperature and Pressure Relief) valve but that is not what was asked. A PRV (Pressure Regulating Valve) strives to keep the pressure the same but when they start to fail, the pressure may creep up when water is not being used. A PRV often includes a backfow preventer which necessitates an expansion tank, granted some water meters also create a closed system.
     
    mliu likes this.
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