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What size point of use water heater should be used to heat water for my washer?

Trudyu | Posted in General Questions on

I have a high efficiency Whirpool washer in my detached garage. I plan to use a tankless point of use water heater for those occasions when I need warm or hot water loads. What are the specification for a water heater to meet my needs?

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  1. iLikeDirt | | #1

    None; don't ever wash with hot water and go the the laundromat on the extremely rare occasions when you feel there's no way around it. :) That's my personal solution!

    Barring that, you'll simply need to match the washer's water usage with the capacities of the water heaters you're looking at. If you want to use tankless, you'll need to get one that satisfies the washer's GPM fill speed. If you want to use a small tank heater, you'll need to make sure the washer doesn't use more water per load than the tank heater stores. You can get these in 2-6 gallon sizes.

  2. jverschu1 | | #2

    After researching these point of service electric, tankless, heaters (avoid when you can any tank on there like these kitchen hot water spigots have: instant hot tea water but constant energy loss) the things to look out for are: your incoming water temperature during the coldest time of the year. We're on a reservoir and the temperature swings from 38F in winter to 65F in summer. So get the lowest temperature info. Then how hot you want to wash your clothes? Not to plug any particular brand but Stiebel Eltron makes very nice point or service heaters that will reduce the flow at times your waterflow exceeds the units capacity. Not good when wanting a full flush shower. BUT for a washing machine you can live with that. It means you can skimp a bit on the capacity. Not for your kitchen sink as seeing the hot water flow go down is annoying. When you know your flow need, once again you can skimp a bit on your clothes washer, and you know your incoming coldest water temp in the year: you can pick your capacity or Point Of Service unit. They draw huge amperage. So you may need an upgrade to your service from the electrical company to your house. Most likely not when you only want a unit for your clothes washer. I'd recommend making full use of the one unit and maybe also hook up the laundry sink to it and know that when the machine draws water, you may get limited on your sink flow. Not many manufacturars have an as detailed and helpful info sheet on electrical draw, flowrates and incoming temperature tables as Stiebel Eltron. Starting there would be good and from there you can roughly translate amperage draw and water flow to other brands of Point Of Service units.
    Only when getting stuck with not having enough amperage to supply a tankless unit you can consider a tank unit. But then you should first look at your other hot water setup in your house as when you have a standard hot water tank: just fill the clothes washer off that. But you may have good reasons to avoid that. Cold washing works pretty darn good too though. BUT the occasional hot wash for stinky towels or bedsheets is nice to be able to do once in a while.

  3. GBA Editor
    Martin Holladay | | #3

    When the water flow rate is slow, my washing machine works fine. It just fills slowly.

    So I think that you can use a relatively low-flow unit if you want to be patient. You can always call Whirlpool and ask to speak to someone in technical help; ask them if the fill feature has a specified flow rate in gallons per minute, or whether the machine can handle water at different pressures and flow rates.

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