http://www.rheem.com/product.aspx?id=09DF2BDD-5E11-4D32-B574-84ACFB8A4619http://globalimageserver.com/fetchDocument.aspx?id=052c9e32-ce37-48d7-8990-9e430f23fef382V80-2 Energy factor is .86 according to water heater industry self-regulated standards.
Rheem pdf says these water heaters are wired for non-simultaneous operation.
Except special order water heaters.
Non-simultaneous operation uses single 240V circuit as described below.
If your water heater is wired for simultaneous operation, and each element is on a separate circuit, that makes your water heater special order. I would guess the reason is for higher first-hour delivery, which implies rapid heating and would likely affect energy factor.
You might want to get serial number off model and call Rheem for specs on that special order.
Your water heater energy factor may be the same because 'energy efficiency is based on the amount of hot water produced per unit of fuel consumed over a typical day.' This means an aircraft carrier can be considered highly efficient despite overall cost. And naturally the guys making the aircraft carrier are also doing the rating.
http://www.energysavers.gov/your_home/water_heating/index.cfm/mytopic=13000Non simultaneous operation means the upper thermostat controls heating functions.
240V goes to upper thermostat first.
When water inside tank is cold, thermostat reads temperature through tank wall.
Upper thermostat turns on upper element until top 2/3 of tank reaches thermostat set point.
Once set point is reached, upper thermostat turns off upper element and sends power to lower thermostat and lower element.
Lower thermostat reads temperature through tank wall, and turns on lower element until bottom 1/3 of tank reaches thermostat set point.
As water cools inside tank, lower thermostat is first to respond since hot water rises.
Lower thermostat turns on lower element until tank again reaches set point.
When hot water faucet is turned on, hot water exits top of tank.
At same time, cold water enters bottom of tank through the dip tube.
The heating cycle repeats.
At all times, the electricity flows through upper thermostat. And upper thermostat is powered by one 240V circuit.
With simultaneous operation, the upper and lower thermostats work in same manner.
Except thermostats are wired separately.
Lower thermostat does not wait for upper part of tank to be heated first.
Lower thermostat turns on whenever lower part of tank cools.
The advantage is more hot water available rapidly when demand is high. This is called first hour recovery.
One method for reducing electric consumption is to set lower thermostat so it only turns on during certain times of day. For example Whirlpool Energy Smart operates in this manner and shaves a few bucks off the bill each month. This says that simultaneous operation is not an energy saver, unless that circuit controlling lower thermostat is set on a timer.
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