PEX Home Run System???

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by mcintoshmc, Dec 11, 2012.

  1. mcintoshmc

    mcintoshmc New Member

    Messages:
    3
    Location:
    Los Angeles
    I am planning on doing a complex PEX install, and have decided to go with the 24 Port Brass PEX Crimp MANABLOC (9 Hot and 15 Cold). It has (2) 3/4 inlets (1) 3/4 outlet, and 1/2 outlet ports. I have a gas water heater closet in the middle of my one story home.

    1) From what I have been told, the manifold "should" be within 10 feet of the Heater. Is that true? The reason why I ask, is that I don't really have a great place to put the manifold, so that it is readily accessible within 10 ft. of the heater, but I do have a great place like 30 ft. away. What are the drawbacks for placing it so far away?

    2) Basic set-up: Do I have this right?

    a) 3/4 line coming from water main to the 3/4 inlet of the manifold
    b) 3/4 line (hot) coming from the water heater to the 3/4 inlet of the manifold
    c) 3/4 line (cold) coming from the 3/4 outlet of the manifold to the water heater
    d) 1/2 lines going to each fixture

    3) In my sinks that do not have a cabinet, I will be using copper stubouts connected to an angle stop. The stubout must be connected to a stud. Correct?

    4) My only access to the showers would be either through the tile, or from the side. Which would you do? I have two bathrooms. The master is a shower tub, and the guest is a shower stall. Behind the master is a recessed linnen cabinet, and behind the guest is a stucco wall in the garage. What would you do?

    5) My biggest concern is replacing the piping for the water heater, it is in a closet in the middle of the house. I'm thinking that I will need to cut the galvanized riser with a sawzall, and then cut into the dry wall for the galvanized connections. I'm hoping that the galvanized isnt connected to a stud, and that when I cut the pipe, and remove the connections at the heater, I will just be able to pull it out. But, how will I be able to get back there to secure the Flex Copper Water Heater Connector to the pex?

    I have far more questions, but I will leave it at that. Thanks for any advice you can provide.
  2. mcintoshmc

    mcintoshmc New Member

    Messages:
    3
    Location:
    Los Angeles
    I meant to say complete vs complex.
  3. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,508
    Location:
    Cave Creek, Arizona
    Going from the main to the manifold and then to the heater would only be done if the manifold is between the main feed and the water heater. WE cannot tell you how to access the tub and/or shower because we would have to be there to make the assessment. The distance from the manifold to the heater is immaterial, but the reason they recommend 10' is to minimize the "cold water draw" when you open a hot water faucet. A longer run just negates some of the reasons for using a manifold. Using one of the hot water ports for a 1/2" or 3/8" circulation line back to the heate would minimize the effect of the long line.
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