Electric Tankless Water Heater for Outdoor Shower?

last year

Hello all. I am installing an outdoor shower at my mountain property in California. There is no gas service available and I don't want to deal with needing to fill a tank. This shower will not get a lot of use and for space and other reasons I don't really want a tank. I've started looking at electric tankless/on-demand water heaters. Opinions are all over the map but the consensus seems to be that they're not great except for very limited point-of-use purposes, which is exactly what I'm doing. We're talking about 1 shower here, maybe a sink, but they won't be used at the same time. The biggest concern seems to be the amount of electricity needed and although that is a concern, for the moment we have very little power demands and 200 amp service. I've read good things about the Ecosmart units, and am looking at the 18 and 27 versions. The 18 looks better on paper due to its lower power needs and lower cost, but the 27 looks better in terms of GPM at lower water temps. (Our water comes from a 200 ft well, so it's pretty chilly.) Any thoughts on this topic will be greatly appreciated. Thanks.

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Comments (6)

Jake The Wonderdog
last year
I agree that electric tankless for this use could be appropriate.

Here's the thing to know: There is no magic. The amount of throughput (GPM) is math - and is entirely governed by the amount of current it draws. Nobody has any design that gets more GPM for less current.

Here's another tip: You may have 200 amp service (meaning the breaker and such) - but I've seen plenty of times, particularly in rural areas, where the lines going to the structure from the utility were way undersized and no-way would they sustain the 80% of the service rating.

I think the 27 is the size you would want. A shower is considered 2.5 gpm. Given your deep well, you would likely be able to run your shower with a little left over. You can eliminate some guesswork if you actually measure the temp of the water.

Of course a small tank heater would solve a lot of issues, but I understand you don't want that.
gadlfy
last year
Interested to know if your outdoor shower meets water conservation rules in your area. I have family in California who are constantly bemoaning the lack of water for their plants etc. Seems like an outdoor shower might run afoul of a few regulations but im not sure exactly where you are.
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The problem is that tankless heaters can heat water for an indefinite period of time (you never run out) but they can only heat so much water at one time (gallons per minute). Think about how long it takes to heat a gallon of water in a pot on the stove. It takes a huge amount of energy to heat, say five gallons, in a minute. A standard shower is about 2.5 - 3 gpm. An electric heater would draw about 120 amps to heat water 70 degrees (from 35 to 105) at that flow rate. You are looking at twice that amount for two of the children's showers at the same time -- and that's about it. The rest of the 400 amp capacity of your electric service would have to go to everything else in your house. In fact, depending on your electrical demands, it might not leave enough. Gas tankless (or condensing tank unit) can do a better job of delivering the required amount of heat at one time -- but I'm assuming that gas isn't available. Your multi-head showers are probably that rate for each shower head. It's really easy to get to 10 gpm or more. At that rate, you can empty a 70 gal water heater very quickly. I can't really help you out much more, you have pretty serious hot water demand and you need someone who can go design your system for you-- including the implications for electrical service and hot water storage. As an aside, I think people get enamored with the multi-head showers without a full understanding of what that requires in terms of plumbing and utilities to run. You might also consider a waste water heat recovery system. They reduce the system demands by pre-heating the incoming cold water using the warm water that is going down the drain. These don't normally have a payback except in situations such as yours.
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Hi bold_as_love. I'm not sure I followed anything you said past "PV". Ok, so let me be clear - there are cases where Point Of Use electric tankless makes sense to provide instant hot water in remote locations. There is virtually no case where whole-house electric tankless makes sense. The amount of current required for a whole-house electric tankless can run 180 amps with at least a 300 amp service. That kind of current almost always means significant upgrades to the electric service. Even then, electric tankless will struggle to provide enough hot water. The savings for Electric Tankless are only about 2-3% over a standard electric tank. Very little standby heat is lost through the insulation on a tank electric heater. An electric tankless heater (or electric tank heater) is NOT something you would ever want to pair up with PV. What is paired up with PV is the hybrid heat pump water heaters. If you look at the energy sticker on a standard electric water heater they will show about $420-500 a year. A tankless electric will be a couple percent less. A hybrid heat pump energy sticker will be ~$110 a year.
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kimwim
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We just built an outdoor shower and used an Eccotemp tankless. Ours is not electric.....it is propane, so can’t answer your question. I wanted to comment though and let you know it is one of the best things we have added to our home. I don’t think my husband or son have showered inside in 2 months. The propane lasts a lot longer than we anticipated, even with 3-4 showers a day!
dadoes
last year
Flow rate at a shower may involve factors other than just the rating of the showerhead. My showers are rated 2.5 GPM but setting the one in the master bath at full-on hot flow my tankless reads only 1.5 GPM. Pressure of the well tank, characteristics of the plumbing design, etc.
Sheryl French
7 months ago
kimwin, which model of Eccotemp are you using. Getting ready to build an outdoor shower here, dedicated use.
kimwim
7 months ago
We have the L10 portable. It can be disconnected easily, if needed

Electric Tankless Water Heater for Outdoor Shower?

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Jake The Wonderdog

gadlfy

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