water heater voltage

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Ponchik

Ponchik

Senior Member
Location
CA
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Electronologist
I have a 208V commercial water heater that needs to get changed (tomorrow) but can not find one that is available by tomorrow for a like replacement. All commercial units for like replacement are 2 weeks out (special order). I do however find a 240V units that I can pick up by tomorrow, but I am not comfortable with the 240 load on a 208 supply. In my mind it may not heat up fast enough or elements may burn up prematurely.

Please give me your thoughts on 240V element on 208V supply.

Thank you.
 
edward said:
I have a 208V commercial water heater that needs to get changed (tomorrow) but can not find one that is available by tomorrow for a like replacement. All commercial units for like replacement are 2 weeks out (special order). I do however find a 240V units that I can pick up by tomorrow, but I am not comfortable with the 240 load on a 208 supply. In my mind it may not heat up fast enough or elements may burn up prematurely.

Please give me your thoughts on 240V element on 208V supply.

Thank you.
Click to expand...

The maximum heat output of the resistance elements will be reduced by a factor of (208/240)2. About 75% of design heat rate.
Whether or not that will cause a problem depends on the usage.
It will be slower to get up to temp from a cold start after installation, and the recovery rate in gallons per hour will reduced by roughly the same factor.
It all comes down to what the expected usage will be.

The elements will spend a higher percentage of the time on, but that is unlikely to reduce the life significantly because the lime deposit buildup and corrosion will take place at the same rate as they sit in the water.
You may also find that you can order a 240V unit and at the same time get 208V replacement elements for it.
If anything they will last longer since the internal temperature of the element will be reduced.
 
GoldDigger said:
The maximum heat output of the resistance elements will be reduced by a factor of (208/240)2. About 75% of design heat rate.
Whether or not that will cause a problem depends on the usage.
It will be slower to get up to temp from a cold start after installation, and the recovery rate in gallons per hour will reduced by roughly the same factor.
It all comes down to what the expected usage will be.

The elements will spend a higher percentage of the time on, but that is unlikely to reduce the life significantly because the lime deposit buildup and corrosion will take place at the same rate as they sit in the water.
You may also find that you can order a 240V unit and at the same time get 208V replacement elements for it.
If anything they will last longer since the internal temperature of the element will be reduced.
Click to expand...

Thank you. :thumbsup:
 
You could remove the 240-volt heating element(s) and install 208-volt element(s), if they're available.
If not, you could install the water heater now -- 25% less hot water is better than no hot water at all -- and exchange the element(s) when they become available.
 
One can also add an autotransformer in line if the fastest recovery time is needed.
 
Thank you guys.

I was able to find the same replacement. But man it took some time. I learned that commercial water heaters are not very readily accessible (at least in this case)
 
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