120v Undersink tankless water heaters

[Music Lover]

Quote:

Originally Posted by Telly So if we need hot water there, we just have to run it. Run it for a while to get it hot before hitting the Start button on dishwasher. Otherwise, the dishwasher heats the too-cool water up to temp, which stretches cycle, and uses more energy electrically ($$) to do so than our gas WH would.

Run the water at first so that hot water is in the pipe close the dishwasher. But rather than wasting it down the sink use it to fill containers for drinking water, a pot for cooking later, or to water the plants.

[38Chevy454]

Late to the discussion, but I agree that if you really want a tankless water heater, you will need to upgrade to a lot bigger electric circuit. That means 230v circuit and 30 or more amps. If you want to stay with 120v, just go with a small tank type heater under the sink. It won't require much more room than the tankless setup. Something like that will give near instantaneous hot water. Or do as the other suggestion and put a recirculating system for your main hot water supply.


The main problem you have is insufficient power at 120v 20A circuit to run a tankless. The solution is to run a small tank reserve, and let the lower power run longer time to heat the water.


I have a half bath in my detached garage, with a 7 gal 120v water heater. It has always produced sufficient hot water for what I want to do in the utility sink. I even adapt a hose to the faucet and use warm water to give dogs a bath where the hot water holds out. The 7 gal is going to take up all the space you might have under a sink, but a smaller one would be possible. Yes the issue of a leak someday is something you need to be thinking about, just like any tank type water heater.

[Music Lover]

Quote:

Originally Posted by 38Chevy454 Yes the issue of a leak someday is something you need to be thinking about, just like any tank type water heater.

True, but a leak in a utility area or basement with a floor drain near by isn't as bad as a leak under a kitchen sink that's possibly surrounded by 1500 square feet of nice hardwood flooring.

[Out-to-Lunch]

Quote:

Originally Posted by Time2 I just got up and read my post about the circulating pump. I meant to say "not energy efficient solution" I wanted to change it but, the edit function is gone. I agree this solution wastes energy in lost heat to the pipes surrounding. But it does work, I had a house with the water heater in the basement, I had a return pipe installed and it work perfectly with gravity alone. The hot water rose and the cold water sunk. Although in this case it only worked at the kitchen sink.

Ahh, I see. If your message read the way you meant it to, I would have nodded my head and said "I'm glad someone understands the tradeoffs of those!"

(On a side note, I do wish the "edit" function lived a little longer than it does.)