Why should I care about electric water heater wattage?


Old 03-28-18, 06:23 AM
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Why should I care about electric water heater wattage?

I'm comparing several A O Smith and Rheem electric water heaters. All have comparable size (50 gallons), 12 year warranty, first hour delivery, and uniform energy factors. The difference seems to be in the wattage and amps. Some are 4,500 watts and 19 amps while others are 5,500 watts and 23 amps. Given that the uniform energy factors are equivalent, I can't understand why these differences are important. Can anyone explain this to me?
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Old 03-28-18, 06:58 AM
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Obviously, one uses more electricity than the other. However, both being energy efficient, its not a big deal to most. But, everyone is different. Some people are energy advocates & are sticklers that if everyone uses more energy than they should, energy will run out (kinda like the fear the government was attempting to put in everyone back in the 70's that there was a gas shortage).
Having said that, those people really do care about the energy consumption of the water heater.

Also, if I am not mistaken (& someone can correct me), the government requires that they put that info on the appliance for consumer info.
Old 03-28-18, 07:07 AM
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I think both of those 50 Gallon Hot Water Heaters will use about the same amount of electricity (providing 3412 BTUs per KWH), and assuming similar insulation, both will suffer about the same amount of wasted heat loss . . . . but the 5500 Watt unit will have a slightly larger set of heating elements and will have a faster recovery rate. That could be important to some families.

Last edited by Vermont; 03-28-18 at 07:56 AM. Reason: corrected spelling
Old 03-28-18, 08:58 AM
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The higher wattage will just heat up the water quicker.

Your energy cost will primarily come from how hot the water is and how much water you use. If both are set at the same temperature and your usage doesn't change then I wouldn't worry about the wattage. Obviously you want to make sure your circuit can handle the higher amperage but I suspect it can.
Old 03-28-18, 12:54 PM
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The differences in wattage is not important but the higher wattage elements will heat the water faster. Most water heater connections are 30A. That would safely power up to a 24A continuous load.
Old 03-30-18, 04:18 PM
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The 5500 watt model will draw more power but will draw the power for a shorter period of time to heat the tankful of water, all other things such as the temperature of the incoming water being equal. The total kilowatt hour usages should be about the same.

Both take the same 30 amp circuit.

It is possible for a load analysis to indicate the need for an upgraded electrical service by switching from a 4500 watt heater to the 5500 watt heater but chances are the installers won't even do a load analysis at this time.
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