Can you put an under sink electric heater on a hot water pipe?


My hot water has a long way to go to get to my bathroom, so I was considering adding a little electric heater and tank under the sink for more immediate warm water.
Is it ok to plumb in the hot water pipe instead of the cold? Any problems with this? I can't think of any off-hand.
Thanks!
Dean
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I am wondering that myself.
In fact my plumber was suppose to check into that for me.
We have a tankless water heater and it will not heat water unless the flow is at least 3/4 gallon a minute.
But my wife likes to run a slow stream of hot water while she does dishes and it seemed the little 110 unit under the sink on the hot water side might just do the trick.
The trouble with those is they can only heat up to 1/2 gallon a minute.
So I was hoping is we needed more than that the main water heater would kick in and pass already hot water through the little heater.
I just now phoned my plumber but got no answer.
If I find out anything from him later I'll post it.
Greg
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The service and installation book for a Power Star AE3.4 elc tankless says; "The unit should be connected directly to the main cold water supply and not to pre-heated water." This is on page 4 of the book I got with the unit about 1 1/2 year ago. Dean(other Dean)
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Hi Dean,
I'm with you on this one. This type of arrangement is common in restaurants and cafeterias where a "booster" tank is used to raise the supply temperature to the dishwasher.
For basic hand washing, one of those small 115-volt, under the counter tanks connected to your hot water line would virtually ensure "instant" hot water on demand. And in terms of supplying your shower, it would act as a "buffer" that would mix/temper the cool water sitting in the line with the hot water stored in this secondary tank; in theory, you wouldn't have to discard this cooler water because it would be brought up to a more usable temperature.
Cheers, Paul

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Well that seems sort of dumb ! You'd need THREE faucets !
COLD, REMOTE HOT, and LOCAL HOT
<rj>
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That's just what the book says..It might be for safety as it is supposed to heat water from ground temp,,pre-heated water might be raised to scalding..Kids would be at risk I guess. Dean did mention a small tank tho,maybe that would be different,,I just offered-up what info I had here.. Dean
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Well there would be a difference, maybe a big difference, between the temp of the hot water when one first woke up in the morning, versus the person who used it long enough for the hot water in the main heater to reach the little heater and come out of the faucet.
I guess these things are intended to totally replace a central hot wh.
It seems like there ought to be a way to do wht the op wants.
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Yes,agreed..I would read the specs for the under sink unit carefully just in case..Maybe the temp settings(if present)can be calibrated to work safely and efficiently..The AE3.4 does'nt have this option but is only one of many styles of tankless.. I am considering using My AE3.4 at My kit sink but will use a cold feed if I do. Replacing the old plumbing that comes from the AE12 and insulating that run might be sufficient for My uses in the kitchen,then I could use the AE3.4 at a utility sink. The runs to kitchen are old steel and need to be replaced anyway.. Dean
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We had a wide ranch house when I was in JHS and HS, and an unheated crawlspace, and the water in the bathroom was always cold. One of my few complaints.
One of the first things I did here was use that 6 foot grey foam with the slit to insulate the hot water in the basement, all the way to my kitchen sink (except for the short vertical part) and my upstairs bathroom sink (except for the 11 foot vertical part). Because I live alone, it didn't help at all. It still stays warm for 15 minutes, but maybe not for a half hour. I don't know how many people would have to be here, how often they would have to use the hot water (every 15 minutes?) for insulation to make a difference. Even with a full house, lots of people, the number of times the hot water gets used every 15 minutes instead of every half hour are probably few. I"m not explaining this well, and I'm not even sure about the numbers, but I hope I've explained it well enough anyhow.

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Recirculation pump.
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Hand washing OK, but showering will be hot, cold, then hot again as soon as you exhaust the lkittle heater.
Better to go with recurcliating pump!
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dean wrote:

If it's a heater with a tank, of course it will work. If it's a tankless heater, it might be dangerous.
Bob
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