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Community and Q&A

120V inline water heater

charles3 | Posted in Mechanicals on

A couple weeks ago, Peter Engle wrote, “My favorite inexpensive, plug-in, 120V inline water heater.” Anybody know the make or model? If not, can you recommend something similar?

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  1. Expert Member


    A Google Image search brough up dozens of models. Similar ones appear to be available at Home Depot and Walmart.

    1. charles3 | | #2

      Thanks, Malcolm. I had no idea that Google has image search. It turns out the model in the photo is in Puerto Rico, not available in the US. And Home Depot and Walmart models cannot really be called "plug-in" since they exceed 1800 watts.

      1. Expert Member
        MALCOLM TAYLOR | | #3


        I had no idea they existed before this thread. Hopefully you can find one that works on a 15 amp circuit.

      2. Expert Member
        NICK KEENAN | | #4

        1800 watts=6138 BTU/hr or about 100 BTU/minute. If you're asking the heater to lift the water 50 degrees for a shower that's 2 lbs per minute, or about a quarter gallon per minute. which most people would find unsatisfactory.

        Probably a gallon per minute is a minimal level of flow, which means your incoming temperature has to be 88F to get 100F water. In Puerto Rico that may not be unreasonable. In most of the US, not so much.

        1. charles3 | | #5

          Indeed, I was not expecting much effect. But they are cheap and I'd be curious if you are correct about the minimum operational flow.

  2. Expert Member
    PETER Engle | | #6

    That's funny. I was being a bit sarcastic, but of course sarcasm doesn't work in text speech. Most electric code experts I know suffer from head explosions when I show that slide because of the 120V power being fed via an exposed NMC cable to the shower head. Water and electricity generally don't mix well. But as the astute people on this board have found, there are UL listed versions that are entirely safe.

    As mentioned above, these can only provide 20-30 degrees of temperature increase at reasonable flow rates. For a tropical climate, you don't really need a "hot" shower, and the ground temperature starts pretty high anyhow, so these are the regions that you tend to see these installed.

    1. charles3 | | #7

      Pete, thanks for weighing in. UL listed versions that plug in? Any idea what amperage is standard for receptacles in tropical climates?

      1. Expert Member
        PETER Engle | | #8

        There are a lot of reasons that you probably won't find a plug-in unit. 15A and 20A outlets at 120V seem to be pretty standard in American-influenced areas, but 240V outlets are more common European-influenced areas. I wish I had enough experience in tropical climates to give a comprehensive survey. Sounds like a good excuse for a business trip....

    2. Expert Member
      NICK KEENAN | | #10

      How do they feel about an 1800 Watt continuous load on a 15 Amp circuit?

  3. GBA Editor
    Martin Holladay | | #9

    Back in 2012, I used that photo as the lead photo in my article on water heaters. My caption read, "An example of a common type of point-of-use electric water heater used throughout the Caribbean and Latin America. This showerhead heater is manufactured by Dur-O-Matic."

    If anyone is interested in learning more about this type of water heater, here is a link to my nine-year-old article: "All About Water Heaters."

    1. Expert Member
      PETER Engle | | #11

      So that's where I stole it from. Thanks for the graphic.

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