# 208V electric water heater replacing a 220V



## 422 plumber (Jul 31, 2008)

I bought a bunch of scratch and dents at my local supply house. My boss wants me to swap one out at his mom's. His mom's is a typical 220V 40 gallon resi heater. Can I install a 208V, single phase commercial in it's place? Or will different voltages matter?


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## gladerunner (Jan 24, 2009)

From what I'm told if your within 20% in voltage diffirential it will still work. but it would probably not be at it's optimum efficancy.


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## user4 (Jun 12, 2008)

gladerunner said:


> From what I'm told if your within 20% in voltage diffirential it will still work. but it would probably not be at it's optimum efficancy.


You will also fry elements faster if you are not using the correct ones.


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## 422 plumber (Jul 31, 2008)

The elements are 4500 watts. That is what is in every 40 gallon resi model I have ever serviced.


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## I'mYourTourGuide (Jun 23, 2008)

I actually think it will matter, for I have some juice carpenter experience, lol.

It will not be very efficient because on the hot feeders coming into the service, 247volts is typical, or in my area anyhow. Efficiency (good power bill, no troubles) equals + or - 10% of the voltage (247) so that's 24.7 volts either way. . . 247 - 24.7 just equals 222.3 to still operate efficiently.


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## PlumberDave (Jan 4, 2009)

Not a bit of difference. it will work just fine.


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## 422 plumber (Jul 31, 2008)

Thanks for all the replies. I will post back if there are problems.


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## grandpa (Jul 13, 2008)

Not a great idea. If the WH is spec'd at 4500 watts/208 volts, then it would actually consume 5991 watts if you connect it to 240 volts. It is a resistive load, and the resistance doesn't change when you increase the voltage. The 5991 watts would draw 24.9 amps, so you are probably OK on that on a 30 amp breaker. The elements would have a shortened life, but you would have good recovery!


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## nhmaster3015 (Aug 5, 2008)

208 - 240 won't make no difference no how. 4500 watt element is a 4500 watt element. Less volts in means a bit less that 4500 watts but not much less. It'll work just fine.


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## 422 plumber (Jul 31, 2008)

It's a two bedroom, one bathroom house. Right now, it's a 70 year old widow who's there. Recovery isn't a problem.


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## grandpa (Jul 13, 2008)

nhmaster3015 said:


> 208 - 240 won't make no difference no how. 4500 watt element is a 4500 watt element. Less volts in means a bit less that 4500 watts but not much less. It'll work just fine.


I might take issue with this. If you had a unit, probably residential, which was spec'd at "208/240" what you say would be true. The elements would be 4500 W at 240, less at 208. But he has a commercial unit, and it may well be spec'd at 4500W @ 208V


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## Protech (Sep 22, 2008)

If they are 4500watts at 240v they should work fine. I've never seen a 4500w at 208V. I know that a 4500W 240V actually uses about 4300W at 208V.


jjbex said:


> The elements are 4500 watts. That is what is in every 40 gallon resi model I have ever serviced.


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## 422 plumber (Jul 31, 2008)

Thanks.


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