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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

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    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

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    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

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    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

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    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

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    Location:
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    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

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    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?
  7. jerryd, Jun 16, 2026 at 2:47 PM
    #7
    jerryd

    jerryd Member

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    Location:
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    Todays update there are no valve at water heater. Bypass for winterization in done by removing inlet and outlet copper flair fitting pipes and install a tubing between them to eliminate WH.
    Today checked Amtrol tank only 3.5 psi. Factory said new tank shipped at 50psi sooo I pumped up tank with bicycle pump to 22lbs. didn't want to rupture diaphragm. Repressured the system filled with water HW turned on. Will check operation tomorrow. If improvement I'll increase pressure with small compressor. I was PIA to pump up with hand pump in the bilge. I'll keep posting.
  8. Greg Page, Jun 16, 2026 at 2:53 PM
    #8
    Greg Page

    Greg Page Senior Member

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    Does it say what ratio the accumulator is? For example, a 4:1 accumulator would want to be pressureized to 1/4 the working pressure when it is empty/no pressure in the water system. For a 60 psi water pressure system (what my boat runs) the no-water pressure in system accumulator pressure is set to 15 psi (what I use). When the water side goes up to 60 psi, the accumuator pressure will read 60 psi too.
  9. jerryd, Jun 16, 2026 at 4:05 PM
    #9
    jerryd

    jerryd Member

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    I haven't seen a ratio. Will check on that. Accumulator is Amtrol WX-102. Tag states tested to 100psi. Testing and pressurizing done with no pressure in system. Our water pressure is 60psi also.
  10. jerryd, Jun 16, 2026 at 4:11 PM
    #10
    jerryd

    jerryd Member

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    Location:
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    From the Amtrol web manual "1. Remove protective air valve cap. 2. Check pre-charge pressure. 3. Release or add air as necessary to set the pre-charge pressure 2 psig below the pressure switch pump cut-in setting. (Example, 38 psig precharge for a 40/60 pressure.) 4. Replace protective air valve cap.
    Greg Page likes this.