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Hot water flow diminishing

Discussion in 'Ask A Hunter Owner' started by Wedgie, Aug 18, 2017. Add this thread to a FAQ

  1. Wedgie


    Joined Jul 30, 2013
    23 posts, 1 likes
    Hunter 45cc
    Au Rosslyn Bay Qld Australia
    We own a Hunter 45CC and the flow to the hot water taps in the heads and galley have been slowly becoming less and less until it is now down to a trickle..
    We have checked the pump filters which had very little debris at all and the pump doesn't seem to have any issues either as the cold water flow is unaffected.
    Our thoughts are that there may be some calcification in the hot water lines or tank (which is under the bed in the aft cabin) and wonder if anyone else has experienced this problem and how they addressed it.
    We would be appreciative of any suggestions.

  2. quadrille38


    Joined Apr 11, 2010
    605 posts, 49 likes
    Hunter 38
    US Whitehall MI
    There is likely a mixer valve on the water heater right where the hot line exits. It's designed to mix the hot with a flow of cold as a way to moderate the temperature and lower hot water consumption as a way to stretch the supply.

    It is brass and has a multi sided plastic knob on top with a screw in the middle. You will see arrows that point to making it hot or cold by bleeding in more or less cold.

    There are screens with fairly small holes on the inlet and outlet sides. These tend to easily scale up. I found some fibers from when the boat was plumbed at the factory.

    I ordered a replacement. It wasn't to bad to install. I did find in the course of replacing it that I likely could have cleaned it.

    There are threads on this so if you search the archives you should find them. If I can locate it, I'll update this response with the links

    I found the thread
    In this thread there is a link to the manufacturer of the product. Also a schematic

    Last edited: Aug 18, 2017
  3. kloudie1


    Joined Nov 6, 2006
    7,670 posts, 450 likes
    Hunter 34
    US Mandeville Louisiana
    I have had hot water side of my sink faucet and the head shower calcify slightly, plugging the valve on that side.. usually though it plugs the aerator screen which affects both hot and cold..
    Look for a mixing valve, later model boats had them from factory.

  4. Wedgie


    Joined Jul 30, 2013
    23 posts, 1 likes
    Hunter 45cc
    Au Rosslyn Bay Qld Australia
    Thanks so much to you both. I'm off to investigate!!

  5. Wedgie


    Joined Jul 30, 2013
    23 posts, 1 likes
    Hunter 45cc
    Au Rosslyn Bay Qld Australia
    Thanks Quadrille38 but couldn't find the link to manufacturer or schematic anywhere. Can you point me in the right direction?

  6. justsomeguy


    Joined Feb 20, 2011
    6,148 posts, 729 likes
    Island Packet 35
    US Tucson, AZ/San Carlos, MX

    quadrille38 likes this.
  7. Wedgie


    Joined Jul 30, 2013
    23 posts, 1 likes
    Hunter 45cc
    Au Rosslyn Bay Qld Australia
    Thanks. Got it

  8. seadaddler


    Joined Dec 19, 2006
    5,319 posts, 109 likes
    Hunter 36
    US Punta Gorda
    Had the same thing happen on my H-36 2007 and it was at the hot water heater where the hoses
    Are connected to the water heater and there are screens that were all clogged and just disconnect the hot water hose coming out of the heater and cleaned the screens and been working great ever since.
    Try the screens and did not do anything the the mixer

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    Hunter Ad Bot

    Joined Oct 27, 2016
    0 posts, 10 likes
    US Seattle
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  10. steve stark

    steve stark

    Joined May 10, 2004
    101 posts, 4 likes
    Hunter 340
    US Bremerton, WA out of Portland
    Another thing to try... We had a factory installed "cheap" plastic check valve at the HW Heater cold water inlet that disintegrated. Replaced with brass - full flow restored.

  11. VT Fitz

    VT Fitz

    Joined Oct 19, 2006
    314 posts, 4 likes
    Hunter 27-3
    US Brownsville, VT/Mystic, CT
    I vote for the screen on the hose coming out of the heater and into the mixer. I was just fighting with that same problem last weekend on my '07 H27-3. We had nothing at all coming out of the hot side. It's been on my to-do list for this new-to-us boat all season, but there were 50+ other items higher up than that!

    After I got it flowing, I had the dreaded rotten-egg smell, so had to shock the system. While flushing through, the hot flow started to slow again. Opened it up and, lo and behold, more crap clogging the screen. I anticipate I may have several bites at this apple...

    My understanding is the mixer more of a scald-preventer when the engine is heating the water. Some folks have eliminated the mixer entirely because of this clogging problem and just are careful to be sure they don't scald themselves by opening cold first at the tap.

    Last edited: Aug 31, 2017