Water Heater Installation

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Gringo, Dec 28, 2012.

  1. Gringo

    Gringo New Member

    Aug 31, 2009
    My plan (up until now?) was to use 1" line for both hot and cold to feed entire house (new construction).
    I just bought a water heater and notice that it is 3/4" both in and out.
    Would I gain anything by going in with the 3/4" but, immediately coming out on hot side, adapting up to 1" to feed all hot water faucets of house?

    Thank you,
  2. Gary Swart

    Gary Swart In the Trades

    Sep 1, 2004
    Yakima WA
    Actually you will lose by increasing the size of the pipe coming out of the heater and going to the rest of the house. The hot water in the pipes will cool when water is not flowing through them. Before you get hot water to the fixture, all of that cooled water will have to be purged (wasted) before you will have hot water. What many of us do is to use a recirculating system which will provide virtually instant hot water at any fixture. Also, 1" is far too large for a house distribution system. Depending on the number of fixtures involved, 3/4" might even be larger than necessary. There are tables that will provide optimum pipe sizes. You should investigate a recirculating system before completing construction as the better ones require a return line...that's what makes the recirculation possible. There are several very good brands available and the cost is not too bad. Many have timers on the pump so they only recirculate at the set times. I have one that does not use a timer that has been in service 24/7 for several years without a problem. If/when the pump fails, it is located where it can be easily replaced. Keep a watch on this thread, someone will likely provide the sizing information in better detail.
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  4. Gringo

    Gringo New Member

    Aug 31, 2009
    Thank you Gary
    I researched pipe sizes on the internet and was surprised to see that, for any normal household fixtures, 1/2" pipe throughout house is sufficient.
    This may be true for a city-supplied water system of high pressure, but as in all houses down here, we use gravity-fed systems (please don't suggest adding pump). Would this 1/2" pipe size still be adequate for a lower pressure gravity-fed system?
  5. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona
    I haave nEVER considered 1/2" pipe of any kind adequate for use "throughout the house". What KIND of pipe are you using. I assume it is plastic CPVC or PEX. If so if you use 1" tubing it will be almost the same as if you used 3/4" copper and 1/2" would be completely inadequate.
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