Plumbing PEX questions

Discussion in 'Remodel Forum & Blog' started by C Wolford, Mar 13, 2019.

  1. C Wolford

    C Wolford New Member

    Jan 23, 2019
    Can't seem to find alot of info on PEX installs. Lots of info on running lines, but not answers to a few questions.

    Location of PEX manifold: (talking 4-5 port for hot, 6-8 for cold)

    Can I put a PEX manifold under a bathroom sink cabinet
    In the wall that has access from the bathroom sink cabinet.
    am I just stuck with access panel in the drywall?

    Washer, dishwasher, icemaker lines:
    Plan on using a hot water mixing valve on the water heater.
    Should I use the bypass for the washer and dishwasher?
    Would this effect the pressure benefits of a manifold?

    If I don't use the bypass should I run single lines for the dishwasher and ice maker or just tee off the sink like the old standard so I can run the hot water to make sure its hot when it hits the dishwasher.

    Thanks for your time.
  2. bcarlson78248

    bcarlson78248 Member

    Feb 24, 2013
    Alexandria, VA
    You will make a lot of connections at the PEX manifold during installation, and you may want to use it often to turn off the water, so I would not put it under a cabinet or any other location that is hard to reach. However, the location is up to you.

    I put my PEX manifold in the wall that runs perpendicular to the side of the sink and at about the same height as the sink mirror. As you stand at the sink, the access panel is at your left shoulder. I used one of the larger metal access panels from HD, painted wall color, and have good access to two 8 port manifolds. I would have prefered to set the panel a little farther back along the wall so it would have been obscured by the open door, but it just wouldn't fit there.

    I don't really understand your need for the mixing valve, so I can't make any suggestions. My hot lines run to bathroom sink and shower, laundry room sink and washer, and to kitchen sink and dishwasher, and they run directly off the manifold. Manifold has 3/4" in and out (to another bathroom two floors above), and 1/2" lines to each fixture.

    My manifold has built-in shutoffs for each 1/2" line, and I added a shutoff for the 3/4" out fitting. It makes isolating fixtures quite simple. It is similar to this manifold, but with 8 ports.

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  4. C Wolford

    C Wolford New Member

    Jan 23, 2019
    Have kids and the wife wont let me put hot water heater over 120, mixing valve fixes this.

    what about PEX manifold and running lines to dishwasher / icemaker or just using them from sink supply.

    Thanks for the input
  5. Reach4

    Reach4 Well-Known Member

    Sep 25, 2013
    Dishwasher receiving full hot water would be best, but most don't bother. Washing machine can get full hot, but laundry tub is not allowed to.

    I see you used an Apple to post. ;-)
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    Many newer mid-range to higher dishwashers today have built-in capability to heat the water if it's not hot enough. But, depending on how you heat the water, it may cost a lot more to heat it unless you have an electrically supplied WH.

    Depending on how far it is to the DW, because it doesn't use all that much water, it may not be fully hot for the whole fill, and the heating in the thing can make a big difference.
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