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Community and Q&A

Should I consider Structured Plumbing in 4500 sq. ft. house?

Cherylann128 | Posted in GBA Pro Help on

Hello and thank you for looking at my question. I hope someone can explain this to me in laymen’s terms.

I’m building a 3 story, 4500 sq ft house that will have 6 bedrooms and 7 bathrooms. I want to make sure the plumbing is designed so I have minimal water and energy waste getting hot water to the fixtures in each bathroom but I don’t know anything about plumbing design. It seems to me the best approach would be to have two separate systems (think duplex) since there is a center hall and most of the bathrooms and kitchen are on one side of the house. However, I can’t find any examples where this has been done, perhaps because it’s too expensive?

I’ve been reading about structured plumbing but I don’t really understand the concept. Not surprising since I’m not a plumber or builder, just a homeowner. So, I’m asking the professionals here. Is structured plumbing the way to go and if so, how can I learn about it? Thanks in advance for your help!

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  1. GBA Editor
    Martin Holladay | | #1

    "Structured Plumbing" is a brand name for a system that uses a circulating pump. For more information on this brand name, see Structured Plumbing®.

    If you are interested in conserving hot water, you might want to read these GBA and Fine Homebuilding articles:

    Hot water circulation loops

    Waiting for Hot Water

    Hot-Water Circulation

    All About Water Heaters

  2. Bond | | #2


    I think you are referring to the use of a plumbing manifold, with separate branches to each fixture or appliance (sometimes called a home run system). Take a look at this for a description:

    If so, I can wholeheartedly recommend it, with caveats. We added a manabloc (TM) system in our basement bathroom, directly linked to the instant hot water heater. The upstairs bathrooms are directly above, so 85% of our water use is concentrated in one place.

    I said a caveat as hot water takes a long, long time to get to the laundry and dishwasher at the other end of the house, so they end up heating electrically sometimes. With hindsight I would have plumbed the laundry and kitchen on a recirculating loop with its own smaller Manabloc. However, this was added complexity and cost I couldn't justify at the time.

    One last point: my plumbing inspector does not like the smaller 3/8 PEX and wanted everything in 1/2" or bigger: a crazy waste of water.

    Hope a real plumber can chime in!


  3. GBA Editor
    Martin Holladay | | #3

    If you are still visiting this post to read new comments (I'm not sure that you are), here's the scoop: a circulating pump is one way to reduce the wait time for hot water. Circulating pumps can waste a lot of energy unless they are controlled by a switch located in the remote bathroom.

    Home-run plumbing systems (systems that include a manifold) are different from systems with a circulating pump. You can have a circulating pump with or without a home-run (manifold) system, although it most cases you don't want a home-run system if you are installing a circulating pump.

    In a house like yours, two water heaters may make sense.

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