Some basic plumbing questions

Discussion in 'Boat Design' started by rsimon, Aug 3, 2014.

  1. rsimon
    Joined: Jun 2011
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    Location: Land locked Florida

    rsimon Junior Member

    Hello, good to have a forum with chance of answering some basic plumbing questions that are not really
    elaborated on in my book: "Understanding Boat Plumbing and Water Systems," (by John C. Payne.)
    I'm in the re-plumbing phase of the restoration of a 1969 River Cruiser houseboat (34' LOA.) I'm converting to
    an outboard set-up (so anyone knows were I can get a good used 4-stroke let me know.)
    I want to use a manifold type distribution (so-called "Water Web" in Mr. Payne's book.) It mentions
    in the Hose Fitting section that "in most cases you will need to use reducers...for 1/2-inch ID hoses."
    I'm going to use 1/2" hoses for all my faucets but the question is does the water line coming in from my
    city water inlet need to be a larger size going into the manifold distribution box and then branch off at the
    1/2-inch lines to faucets? Also, does this count also for the water line going from my D/C pump going into manifold?

    There looks to be about 3 major Pex fitting companies with their own ways to connect: 1) "Flair it" 2) "Apollo Pex"
    and 3) "Sea-Tech" which are either push-on assembly or crimp on deals. I would like to go with cheapest and
    most widely available (like at Home Depot or Lowe's and without special ordering etc.) but I wondered about how other
    people's experiences have been with using the Pex one better than another?

    On another note: is it recommended I use an accumulator tank with the use with the newer on-demand D/C water pumps
    (I hear that the accumulator tanks are not needed with those newer pumps because the circuitry precisely senses the flow/demand
    for water immediately.) Anyone with experience with those newer D/C pumps from Shureflow etc?

    Any ideas on a good hot water heater? I know you can go with the Cadillac of marine hot water heaters (Isotemp) and you
    can use a simple on-demand hot water heater, but any experiences with what's been successful out there?
    The book by Mr. Payne suggests not using a water heater with element ratings that exceed 1,200-1,800 watts.

    I appreciate the people who read the post, but appreciate more the people who respond to the post, thanks so much,
    Roger...and almost forgot...check out some of the renderings made over past year on my (external) photo-sharing site: water system
    Last edited: Aug 3, 2014
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    FAST FRED Senior Member

    You will need a deck connector to go from 3/4 hose to an easy to operate cut off valve as it is very dangerous to leave dockside pressure water hooked yo while not aboard.

    Also needed is a pressure regulator as dockside pressure varies up to 90psi.On the hose from a RV store is best.

    I much prefer to only use the on board pump, and a dock hose just to fill a tank.

    If the tank has a large bottom dump, it helps when you get to a good water dock, much city water taste like old swimming pool.

    No need for a marine HW heater an outboard cant power it.

    Although Pex is common in houses my favorite for boats is copper tubing.

    1/2 copper tubing with soldered ends is not expensive , for an offshore vessel 5/8 with flair fittings is the gold standard.

    Be sure to have ZERO clear plastic in any part of the system as even minor light will promote green stuff to grow in the system.
  3. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    Pex is being used in most production boats now. Once you get the hang of crimping the connections, the jobs goes really fast. I have nothing against copper, except the cost.
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