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Hot water issue

Discussion in 'Post Yacht' started by jerryd, Jun 14, 2026 at 11:45 AM.

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  1. jerryd, Jun 14, 2026 at 11:45 AM
    #1
    jerryd

    jerryd Member

    Joined:
    Aug 30, 2010
    Messages:
    42
    Location:
    montrose, ny
    Looking for some advice. Here is the issue hot water fluctuates form all faucets and showwers. We have a 20gal hot water tank. 110v well pump with Amtrol tank for constant pressure. Three sinks 2 showers. This is how Post equiped the boat. Hot water tank replaced 2009. It is not leaking no signs of corrosion. It is making hot water.
    Amtrol tank seems OK air comes out of schrader valve. I have changed check valve at cold water inlet to hot water heater thinking it failed, no improvement in temp fluctuation. Cold water enters from bottom of tank, discharge is at top side of tank. Don't what to be a parts charger without a good solution. thanks for your help.
    Jerryd 1990 46Post.
  2. Capt Ralph, Jun 14, 2026 at 1:35 PM
    #2
    Capt Ralph

    Capt Ralph Senior Member

    Joined:
    Sep 8, 2004
    Messages:
    14,418
    Location:
    Satsuma, FL
    Is your water pressure changing when the pump cycles?
    How large is your Amtrol accumulator?
    Could also not be enough of an air charge in the accumulator.
    Do you have an over-temp mixing valve?
    And finally my fav; Somebody been messing with the pump pressure switch?
    High water pressure does not consistently flow thru skinny copper tubing well.
    Lower the switch pressure back down.

    I had a good bug on our Bertram.
    The transom shower has hot&cold knobs. Also a shut off valve to the shower wand.
    The knobs were left both open and the wand was off.
    When we showered in the boat, strange hot water operation.
    The water was mixing back at the transom and cool water flows easier that hot.
    After chasing the water heater for issues, by accident found this bug at our transom. Closed the knobs then all was good.

    Do you have a shower like this?
  3. jerryd, Jun 14, 2026 at 2:41 PM
    #3
    jerryd

    jerryd Member

    Joined:
    Aug 30, 2010
    Messages:
    42
    Location:
    montrose, ny
    Thanks for quick response.
    no transom shower, haven't touch pressure switch in years 60psi doesn't seem fluctuate when pump comes on. will verify that.
    I don't have mixing valve. Amtrol is 4gal it was replaced b-4 water heater prox 2005. Good question on amtrol pressure will check on that.
  4. Capt Ralph, Jun 14, 2026 at 5:55 PM
    #4
    Capt Ralph

    Capt Ralph Senior Member

    Joined:
    Sep 8, 2004
    Messages:
    14,418
    Location:
    Satsuma, FL
    Is this a sudden issue or always been an issue?
    Any other showers on board that could dup my transom issue?
    Your sure no over-temp mixing valves?
  5. jerryd, Jun 14, 2026 at 9:33 PM
    #5
    jerryd

    jerryd Member

    Joined:
    Aug 30, 2010
    Messages:
    42
    Location:
    montrose, ny
    New this year.
    Possitive no mixing valve.
    2 showers on boat. Will check tomorrow! But we always turn valve body off. There is a diverter at each shower head to change from head to hand held. These were installed by me when we purchased boat in 2000. Has been functioning ok up till this season.
  6. LenR, Jun 15, 2026 at 9:31 PM
    #6
    LenR

    LenR Member

    Joined:
    Jan 13, 2026
    Messages:
    31
    Location:
    Long Island
    Check the valves at the water heater, more so the WH bypass for winterizing. Hot & cold open Bypass closed. I see you are in NY and is new this season?