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Thread: Tankless water heater: Point of use

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    DIY Member ron in sc's Avatar
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    Question Tankless water heater: Point of use

    Is there any rule of thumb for distance to the end use when using an end use tankless electric hot water heater?

    I an considering putting one in my garage. Useage will consist of front loader washing machine, sink, and shower. Shower will rarely be used. Tank would be mounted in a closet next to washing machine. Circuit breaker is only 30 amps.

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    Retired Defense Industry Engineer jadnashua's Avatar
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    Unless you can upgrade the circuit, forget about a tankless...the volume of hot water would be very small, if you can even find one that small. You might think of a 30A as a water warmer...30A is okay for most water heaters. Spend a little bit and insulate the walls of the closet well.
    Jim DeBruycker
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    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    DIY Member ron in sc's Avatar
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    Spend a little bit and insulate the walls of the closet well.
    The garage is well insulated because it has air conditioning and heat. It would be more trouble than I would want to undertake right not to change to 6 or 8 gauge wiring. I think I could change circuit breaker and up amperage and make it a 120 volt outlet if that would be of help.

    I did find a 220 volt Bosch unit rated for 30 amps. Do think that would be inadequate? It's the one in link below.


    http://www.cpotanklesswaterheaters.c...e7-2_spec.html

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    In the Trades Gary Swart's Avatar
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    Several years ago, I found a small tank less heater for my shop utility sink. When I finally installed it, my subpanel in the shop was too small, so I had to run a special circuit from the house to the shop. I required #10 wire and 220 vac. It's really a pitiful device, but I do get hot water to wash up after working in the shop or yard. It would never work for a washing machine or shower. A tank less heater big enough for what you want would be extremely expensive to buy, very expensive to install, and they require frequent service. You would be far better off to install a regular water heater.

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    Master Plumber Redwood's Avatar
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    Degree Rise at 0.75 GPM Flow Rate 63F
    Degree Rise at 1.0 GPM Flow Rate 48F
    Degree Rise at 1.5 GPM Flow Rate 32F

    How long do you want to wait for the washer to fill up?
    This thing barely makes enough hot water to wash your hands with at a lav sink!

    What is your incoming water temperature in the middle of winter?

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    Retired Defense Industry Engineer jadnashua's Avatar
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    Power is amps x volts, so, halving your voltage to get the same power, you need twice the amps...switching to 120vac will just mean your leads are even less capable of producing the heat you want.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    Moderator & Master Plumber hj's Avatar
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    Default heater

    It's a good thing the shower is not used much, because whenever it is used you should be prepared for a cold shower because 30 amps is not going to give much hot water. You may be lucky to get warm water for a shower. There is nothing that keeps you from putting the tankless heater wherever you want it, but the rationale for a tankless is that it can, and should, be installed as close as possible to the major usage area.

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    Plumber jimbo's Avatar
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    Quote Originally Posted by ron in sc View Post
    I think I could change circuit breaker and up amperage
    Don't even think about upping the size of a circuit breaker, unless a licenesed electrician tells you the circuit wire is sized for the amps you want. Likely it is not, because a builder would only put in the size wire needed for the circuit as installed.

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    DIY Member ron in sc's Avatar
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    Don't even think about upping the size of a circuit breaker
    ,

    Yes, I need to forget about that I checked and the wire is only 10 gauge.

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