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Thread: Help me choose water heater for 6 bedroom house

  1. #1
    DIY Junior Member jleonardwv's Avatar
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    Default Help me choose water heater for 6 bedroom house

    I have four children ages 13 and under and one on the way. With my wife and I, that makes 7 in the family. We are building a new house, and I'm brave (read stupid) enough to do a bunch of the work myself, including the plumbing. I've lurked around this forum and looked very critically at lots of tankless water heaters, but I'm not convinced this is the best solution. The new house will have gas for the furnace, water heater, cooktop, etc. We will have three bathrooms totaling 5 lavatory faucets, 2 showers, 1 shower/tub, and 1 large tub.

    We currently have a 40 gallon electric water heater that we will leave behind in a few weeks as the house is sold. At our current usage, I can usually get two little ones bathed and one of the older kids can immediately have a shower, no problem. After perhaps 1/2 hour, another shower is possible. Our typical "long shower" is no more than 15 minutes. I am mostly the one who takes longer showers. My wife will sometimes run the dishwasher or clothes washer and take a shower at the same time. She doesn't run out of hot water.

    Considering future needs, such as several teenagers taking long showers, is tankless the best solution? I have no particular preference tank vs. tankless.

    Also, I'm not a pro, so I might need help on the install no matter what.

    Thanks for the input,

    jleonardwv

  2. #2
    DIY Senior Member lifespeed's Avatar
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    I have had excellent results with Noritz NRC1111 tankless.
    http://www.noritz.com/residential-products/nrc111dv/
    It is one of the higher capacity models available. It also has a large heat exchanger resulting in very low pressure drop across the heater at high flow rates. Most other tankless drop significant pressure at high flow rates. Be sure to consult a gas pipe sizing chart to meet the 200K BTU gas supply requirement, and confirm the gas meter is up to the task. Also do a hardness test (Hach 5B is a good kit) and install a water softener if needed to eliminate scale build up inside the heater.

    Edit: Be sure to install the optional flush valves for easy servicing.
    Last edited by Terry; 08-24-2013 at 12:42 PM. Reason: added link
    Lifespeed

  3. #3
    Forum Admin, Expert Plumber Terry's Avatar
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    On the low end, you could also get by with a 50 gallon gas tank, with tempering valve.
    This allows you to run the tank on the high setting, 180 degrees, and mixing it down to 120 degrees with cold. It's sort of like having a 75 gallon tank.

    I'm currently using a tankless at home, and it is kind of nice to have endless heated water.

  4. #4
    DIY Senior Member dj2's Avatar
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    Consider these options:

    1. High recovery 50 gallon tank.
    2. Two 40 gallon tanks.

    I'm not a fan of tankless.

  5. #5

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    Since its new construction, I would say go tankless. The install cost is going to be much less then doing a retrofit later on down the road when you have teenagers. Having endless hot water is nice, I have one in my home.

    Skip past all the glossy brochures and go straight to the flow rate charts. The glossy brochures will say something like 8.5 GPM. Sure, if you only have a temperature rise of 20-25 F. The flow rate drops as the needed temperature rise increases (basic physics). Also, take the flow rate charts with a grain of salt. These are conducted in labs under ideal settings, not real world applications.

  6. #6
    In the trades Dana's Avatar
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    A 50 gallon tank + drainwater heat exchanger will do as much or more for efficiency & capacity on the anticipated long teenaged shower end, at a lower price point, with lower maintenance, and less wasted water from ignition delays. A condensing 50 gallon tank like the Vertex (the cheaper one with the 76K burner) would do even more for efficiency when combined with a drainwater heat exchanger, and still would come in at about the same total installed cost as a condensing tankless. The only time that combination would come up short is if you were doing multiple tub-fills either simultaneously or in rapid succession, yet the recovery rate is quite good- the wait between tub fills would not be long.

    A 76K condensing burner + drainwater heat recovery can deliver the endless shower experience, or even two simultaneous endless shower experiences if low-flow shower heads are used. But the "apparent efficiency" during those shower draws will be greater than 100%, with about half the heat for the shower being recovered from the drain rather than from the burner.




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