Takes too long for hot water upstairs.

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by mikeangelini, Jul 23, 2013.

  1. mikeangelini

    mikeangelini New Member

    Dec 10, 2007
    Philadelphia, PA

    I am in the middle of a foyer/ kitchen / hallway renovation.

    I am removing drywall and have to re route the upstairs hot and cold water feeds due to the addition of a food pantry and doorway where the pipes are currently located.

    My hot water heater (gas 40 gallon tank) is on one side of the house, not in the middle.

    The hot feed is 3/4" copper from the tank to the center of the house (about 25 feet), and then up to the 2nd floor (9 feet ).

    From there reduces to 1/2" copper and travels another ~6-8 feet to the upstairs bathrooms.

    Since I am forced to move the plumbing anyway, I was considering adding a small manifold at the heater tank, and running 2 separate, 1/2" pex lines directly to each bathroom.

    Reason being, I want to waste less water waiting for it to fill up all that 3/4 copper with hot water. I also want to be able to run both bathrooms at the same time.

    The hot water tank is fed with 3/4" copper.


    Does this sound logical?

    Will it significantly reduce the time it takes the hot water to get upstairs? (a lot less waste water?)

    Will using 2 separate 1/2" pex lines significantly improve pressure?
    (I could just use one 1/2" line for both and hopefully decrease the waiting for hot water, but what about when both showers are running?)

    Should I wrap the pex lines in foam pipe wrap?
    (The basement gets rather cold in the winter. Not freeze cold, but chilly.
    I read that some pex cant be wrapped with pipe wrap. Some kind of reaction? I also read lots of people saying that is BS.)

    If yes, wrap the pex lines, should I wrap each bathroom hot supply separately? Or in the same, larger foam insulation?
    Wondering if the cold water in one supply would suck more heat off the one being used, than just being un-insulated...

    The basement walks outside, and has a sliding glass door, which sees a few hours of sunlight a day.

    Should I use the foam pipe wrap to protect the pex from sunlight?

    Thanks very much for any help with this long winded question(s)....,

  2. Gary Swart

    Gary Swart In the Trades

    Sep 1, 2004
    Yakima WA
    Just insulating pipes alone won't help. Insulation of anything only slows heat exchange. What I would suggest is a recirculation system. The best ones require a return pipe, but if you have walls open running a return line should not be too difficult. There are several brands on the market that work well. I use a Laing and it has worked very well for several years. You can get them with or without timers. A recirculation system give virtually instant hot water. It is wise to insulate the hot water and return line to retain as much heat as possible.
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  4. leejosepho

    leejosepho DIY scratch-pad engineer

    Nov 23, 2006
    disabled-retired industrial fabricator
    200 miles south of Little Rock
    I would leave that as it is, then run new 1/2" lines to the bathrooms from there...then use the old 1/2" lines as the first sections of a two-into-one 1/2" circulator return line back to the bottom of the tank.

    The 3/4" might need an additional couple of seconds to fill with hot water and warm itself, but I cannot imagine the difference in volume between 25' of 3/4" and 1/2" ever being noticable on your gas bill. Also, I believe the 3/4" to the center of the house should be able to suppy both bathrooms simultaneously without any significant compromise of flow.

    Note: My own Taco recirculator (for a 60' run) is wired to come on when the bathroom kight is turned on, and hot water becomes available within about 10 seconds with no water being wasted.
    Last edited: Jul 23, 2013
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    I'll second adding recirculation into the picture...I have a retrofit version (i.e., no dedicated return line), but it has a unique feature, a user adjustable aquastat. That is at the vanity. The shower gets hot first in the layout, so I adjusted the aquastat to shut off when it gets warm there verses hot. This minimizes how much warm/hot water gets pushed into the cold water pipes. As a result, flushing the toilet pretty much purges that warmer water from the line, so I have both hot and cold at the vanity after the toilet refills, and full hot at the tub/shower. Dedicated return line(s) means not having the cold line getting heated.
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