Commercial tank water heaters in resi

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electrofelon

electrofelon

Senior Member
Location
Cherry Valley NY, Seattle, WA
Just a heads up, I like these things. I know most of us here aren't fans of on demand electric water heaters: Complexity, cost service size issues, unsteady water temperature..... But for those of us that are concerned about running out of water and/or have eight teenage daughters taking showers at the same time, check out these "light commercial" units. AO Smith has a series that has a 66, 80, and 119 gallon. They are made for 12.2KW @ 277, but are manufacturer approved to run at 240, and the two elements can be set to run separate or simultaneous, so either 4500 or 9000 watts. I'm hooking one up this weekend, big boy 119 gal and we are hooking it up for the 9kw. I'll let you know how it goes.
 
electrofelon said:
Just a heads up, I like these things. I know most of us here aren't fans of on demand electric water heaters: Complexity, cost service size issues, unsteady water temperature..... But for those of us that are concerned about running out of water and/or have eight teenage daughters taking showers at the same time, check out these "light commercial" units. AO Smith has a series that has a 66, 80, and 119 gallon. They are made for 12.2KW @ 277, but are manufacturer approved to run at 240, and the two elements can be set to run separate or simultaneous, so either 4500 or 9000 watts. I'm hooking one up this weekend, big boy 119 gal and we are hooking it up for the 9kw. I'll let you know how it goes.
Click to expand...
When that puppy calls for heat, you'll be able to hear the meter disc whining from across the entire house. :LOL:
 
electrofelon said:
Doesnt that come out to 37.5A🤔
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I read it as the 9 kw was rated at 277 and being ran on 240.
It's the voltage squared thing.
That is why I mentioned, If I read correctly.
240/277 squared 2= .75
9000*.75=6750/240= 28.125

Then there the branch circuit accordingly to the name plate issue. If the name plate max OCPD for the 9 kw the branch has to be sized to it. Now in my home 🤔
 
When your done let me know what it pulls. Maybe a pic of the name plate as well. Would be cool to see what it pulls compared to some math.
Be sure to get voltage at unit with it running as well. Compare volts and amps.

Eight girls. Oh my
I thought two was bad and they had there own 40 gal quick recovery.
 
Tulsa Electrician said:
I read it as the 9 kw was rated at 277 and being ran on 240.
It's the voltage squared thing.
That is why I mentioned, If I read correctly.
240/277 squared 2= .75
9000*.75=6750/240= 28.125

Then there the branch circuit accordingly to the name plate issue. If the name plate max OCPD for the 9 kw the branch has to be sized to it. Now in my home 🤔
Click to expand...
@ 277 it's 12.2KW. I'll probably put one of these in my place next time I need one. So it's not bad it's a 50 amp circuit but that will certainly have some nice recovery. ⚡
 
electrofelon said:
Just a heads up, I like these things. I know most of us here aren't fans of on demand electric water heaters: Complexity, cost service size issues, unsteady water temperature..... But for those of us that are concerned about running out of water and/or have eight teenage daughters taking showers at the same time, check out these "light commercial" units. AO Smith has a series that has a 66, 80, and 119 gallon. They are made for 12.2KW @ 277, but are manufacturer approved to run at 240, and the two elements can be set to run separate or simultaneous, so either 4500 or 9000 watts. I'm hooking one up this weekend, big boy 119 gal and we are hooking it up for the 9kw. I'll let you know how it goes.
Click to expand...
I have an 80 gallon and have seen up to 120 gallon. The ability to run both elements I have not seen, without field modification anyway.

Around here has been somewhat common to see two 50 gallon units piped in parallel. My HVAC guy told me that having two tanks like that adds more cooling load to his calculations when selecting a system and that a single larger tank has less cooling load to plug into his calculations is one reason I went with the 80 gallon tank instead of two 50's. I've never had shortage of hot water other than some rather unusual situations. I never had four plus teenagers in the house either though, just two and an occasional guest maybe.
 
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