Atmor Instant Tankless Electric Water Heaters

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Atmor Instant Tankless Electric Water Heaters
Price: $80.99 - 99.99
Shipping Options: $5 Standard
Shipping Estimates: Ships in 3-5 business days (Tuesday, Jul 15 to Friday, Jul 18) + transit
Condition: New


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That tech info table has an error.

The AT900-13 using 55 amps, on a 60 amp breaker cannot be 8awg wire. 4 awg is more like it.

Smaller numbers are bigger wire. The smaller heaters are listed as 6 awg wire which looks correct for a 40amp load. The largest heater has to have the largest wire, not smaller wire.

I emailed the guys in charge. I’ll update my post when I know more. Thanks for pointing it out!

Way to go Koi!!

Time to learn all about installation along with links to assembly instructions and manual

No tanks :slight_smile:

If interested, here’s a site that rates water heaters and other HVAC related systems on a 1-5 scale: point of use heaters

The tech table is indeed incorrect, but so is your recommendation for wire sizes.

Electrical code for residential wiring size relative to ampacity is slightly different than other applications. Residential loads of 60 amps require a minimum wire size of #6 AWG, not #4 AWG. 40 and 50 amp loads only require a #8 AWG.

#4 AWG gets you to 100 amps in a residential application.

On a different subject, the chart in the specs should rate gpm according to temperature “rise” not “rinse.”

We have a tankless water heater installed and it’s great, highly recommended. Much better than keeping heated water sitting around just waiting to be used. Plus the near endless supply of hot water is a huge benefit.

However, I suggest going for the gas burning type versus electric as the electric ones take longer to heat up. Also note that minimum flow rate to kick it on, go less than that on the hot water side and it won’t start or will suddenly turn off (so if you’re only using lukewarm water at the spout the tank only sees a fraction of the flow). We had that problem with our shower as I run colder showers and the heater kept shutting off, the trick was to change the temperature on the heater so the hot water flow was enough to activate the tank.

Is your tankless heater electric? If so, does it provide hot water for the whole house or would you need more than one heater for that? Finally, if you heater is electric, what do you figure the operation cost of the heater is to you? (I know it must be considerably more expensive than natural gas.)

By the way, the last time I replaced my water heater, it cost me just about $800 to buy a 60 gallon gas fired heater…and I installed it myself. I looked at the gas fired tankless heaters and they were even more expensive.

You would be hard pressed to find an electric tankless that can handle the whole house. You’d also have to have some pretty impressive wiring. For whole-house tankless, you pretty much have to go gas. I just bought a Rheem unit and they are definitely more expensive than the tanked heaters. The improved efficiency is also somewhat overstated with most of the models. You’ll save some money, but it will take a very long time to pay off the extra costs of installation and maintenance.
With that said I have nothing to add about this point of use model, except to say it is good for pretty much only one sink or appliance.

Just want to add:
#6 THHN wire is rated for 75 amps. When bundled as romex, it is rated for 55.

I’m thinking of going to solar hot water when my existing electric unit dies and needs to be replaced. Could this unit be hooked up downstream of a solar unit’s output for an extra boost of heat?

How does 55 Amps save money? Thats half of one electrical service!

And, my new hot water heater is so well insulated I’ve never heard it go on when hot water wasn’t being used.

Finally, my parent’s Bosch unit was so inconsistent {water turns cold during use or didn’t switch on} they replaced it with a standard tank type.

Yes, it is a perfect solution for that.

The highest wattage available on this w00t is 13,000 watts. 1,000 watts is 3412 BTUs. So 13KW is 44K BTUs.
A standard gas tank 40-50 gallon water heater is usually 40K BTU.
So this isn’t really anymore powerful than your basic gas water heater, except it has no buffer if the load becomes too much (no tank).

Furthermore, if you are into efficiency, tankless isn’t the best option.

The best option is to have a tank and have it heated with a heatpump. This can heat the water in the tank at 200+% efficiency since it is pumping heat out of the surrounding air, into the water in the tank. GE Geospring is good.
Helps to keep the garage dehumidified in the wet months, and a bit cooler than otherwise in the summer.


Not sure how much I can rely on 47 reviews with one 5-star rating, one 3-star rating, one 2-star rating, and forty-four 1-star ratings.

My 2 cents: I lived in a townhome for a year which had a tankless water heater. Pros: endless hot water. Cons: it broke 3 times in that year, with various parts having to be replaced.

I have an 80-gallon standard water heater in my house now (3BR, was a rental, hence the large size), and I can take as long a shower as I please without the water cooling off; my current water heater hasn’t flinched with regular use.

Another thing to consider is calcium or other deposits causing more maintenance. My take on tankless is that they’re a nice gadget, but far from flawless. Think of it along the lines of electric cars vs internal combustion when considering maintenance and upkeep, in that you probably won’t be saving that much, long-term.

I did indeed have a whole house electric tankless water heater for a bit.Also had a flow restricter and a filter installed with it. Endless hot water was great. Even saved about 20 dollars a month on my electric bill. Too bad a nasty storm destroyed it along with a few other electrical devices. Back to tank.