# Under the sink electric on demand heater



## dtech (Jul 18, 2020)

Our bathroom in the master bedroom is the one primary used but it's a long ways from the gas hot water heater in the garage, perhaps 50' with water, I've not measured how much water is wasted (maybe 8 gallons) until the water is hot, considering installing an on demand 120v electric water heater, On amazon I see this :

*Bosch Electric Mini-Tank Water Heater Tronic 3000 T 2.5-Gallon (ES2.5) - Eliminate Time for Hot Water - Shelf, Wall or Floor Mounted*
Any thoughts on how effective this would be, would I be better served spending more money on something larger ? Conceivably I could run a 240V line in the crawl space from the kitchen but if a 120v heater would work reasonably well I'd go that route. I don't think insulating the hot water feeds in the crawl space would make much differnece as it's an insulated space and seems to stay around 55 f degrees. I have gas heating but that would be an undertaking and likely cost prohibitive.


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## Jim Port (Sep 21, 2007)

Do you have a way to get a dedicated circuit to the bathroom?


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## dtech (Jul 18, 2020)

Jim Port said:


> Do you have a way to get a dedicated circuit to the bathroom?


I do have an unused 240V circuit as the orignal electric stove was replaced with gas, but it's also a good distance away and I'd have to put in the wiring and outlet (last time I priced wiring it was absurdly high) .

The existing circuit in the bedroom is a 20 amp GFI , the lighting is all LED and my wife occasionally uses a hair dryer but not at the same time as water is running. So the bosch heater I believe draws 1440 watts or ~ 12 amps.


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## Jim Port (Sep 21, 2007)

The heater is going to need a dedicated circuit.


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## dtech (Jul 18, 2020)

Jim Port said:


> The heater is going to need a dedicated circuit.


ok, thanks for your advice. care to render an opinion as to whether or not what I'm considering makes sense to do ?

water is reasonably priced where I reside (high base bill, then additional use is reasonable) but to get hot water it takes approx 40 secs of full open faucet in the warm months and about 10 secs longer in the colder months.

natural gas is of course less costly than electric heat.

thanks


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## SW Dweller (Jan 6, 2021)

A recycling pump would be easier









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## gthomas785 (Mar 22, 2021)

After you run your 2.5 mini-tank out of hot water, it will be full of the cold water from the line. Unless you install a true on-demand heater, you will still get the slug of cold water. It will just be delayed by 2.5 gallons.


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## Elmer-Dallas Texas (9 mo ago)

SW Dweller said:


> A recycling pump would be easier
> 
> 
> 
> ...


Recycle uses lots of energy if you let it run all the time but you can put it on a switch.
Depends how much water you need at a time. 
If just at sink, Bosch is great.
If you want it for shower you will need bigger unit.


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## Elmer-Dallas Texas (9 mo ago)

gthomas785 said:


> After you run your 2.5 mini-tank out of hot water, it will be full of the cold water from the line. Unless you install a true on-demand heater, you will still get the slug of cold water. It will just be delayed by 2.5 gallons.


Nope. The Bosch delivers hot water in less than 4 seconds and normally don't use more than 1 gallon at sink. It will reheat quickly.
I would connect to cold water line.
I have several Bosch 2.5
I love them.
If you only need small amount of water at a time, this might work. On Amazon there are some on demand 110v units for less than $100 that are not recognizable brands. I would consider those because they are cheaper and smaller. But I will be careful because they are not proven manufacturer.


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## Thom Paine (Nov 24, 2021)

Today, most fixtures use less than 2 gpm. 
Not sure how you're using 8 gal. waiting for hot water @ 40 sec. ?

That considered...
Now... what's the ROI for your additional heat costs ?


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## Elmer-Dallas Texas (9 mo ago)

I don't want to wait 40 seconds for hot water to wash my hands because I wash them a lot. And I want to use hot water. Therefore undercounter water heater is imperative for me.


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## Elmer-Dallas Texas (9 mo ago)

Jim Port said:


> circuit


Why would he need to add dedicated circuit to run 12amp appliance? He already has 20amp circuit.


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## SW Dweller (Jan 6, 2021)

Fixed appliances are required to be on separate circuits per the NEC. This is true of the dishwasher and the garbage disposa as well. Some AHJ's allow for the dishwasher and garbage disposal to be on the same circuit. This is in how the AHJ's adopt the NEC which they are entitled to do.


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## Elmer-Dallas Texas (9 mo ago)

I think it is only possible to recycle / recirculate if you have a return loop. 
For shower, I think that 2.5 Bosch is too small. If you are willing to take quick shower, maybe 7 gallon will work if you have room for it within 3 feet of the shower.


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## chandler48 (Jun 5, 2017)

Definitely have a return loop on a recirculating pump. The thermostat will tell the pump to turn on and it will move hot water to the furthest outlet then turn off. I have installed more of the recirculating pumps and removed more of the "instant" water heaters.


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