This means that between 75 and 95 percent of the energy used to heat the water ends up being delivered to your taps as usable hot water.
Water heater energy factor list.
A heat pump water heater with an ef of 2 0 and an electricity cost of 0 0842 kwh.
Ef is determined by the department of energy s test method outlined in the 10 cfr parts 200 to 499 edition revised as of january 1 2014.
The new uef rating method improves the industry s ability to.
An older measure of water heater overall efficiency that is being phased out due to new test methods for water heaters.
Beginning june 12 2017 ef ratings will be replaced with the new industry standard for measuring energy efficiency in water heaters called uniform energy factor uef.
365 days year x 12 03 kwh day ef x fuel cost kwh annual cost of operation.
You need to know or convert the unit cost of electricity by kilowatt hour kwh.
The higher the ef value is the more efficient the water heater.
The typical energy factor for a gas water heater is between 0 5 and 0 7.
As of september 1 2010 a water heater needs to have an energy factor of 0 67 or higher in order to qualify for the energy star label.
Expressed as a decimal the uniform energy factor is determined by running a department of energy specified simulated use test sut.
The uniform energy factor.
For gas condensing water heaters the energy factor must be 0 8 or higher to qualify for the energy star label.
Simplify the water heater selection.
It s important to note that energy factors can vary significantly depending on their fuel source.
The uniform energy factor for residential and certain commercial water heaters refers to its efficiency when run under standardized conditions for a 24 hour period.