Marketed as replacements for electric resistance units, HPWHs promise to save considerable electric energy and money over traditional ERWHs.
According to the U.S. government EnergyGuides for a 50 gallon ERWH with an EF of 0.90 and a HPWH with an EF of 2.35, a HPWH could save 2,684 kWh per year for an average family. These water heaters are considerably more expensive to install than traditional ERWHs, but electric savings will likely save more money over the course of the water heater's life. The below table shows the installation and annual operating costs, according to the National Renewable Energy Laboratory's (NREL) National Residential Efficiency Measures Database and the U.S. government Energy Guide labels.
HPWH vs. ERWH (U.S. Government EnergyGuide Labels)
||Annual Electric Usage
||Annual Operating Costs†
|HPWH (50 gal, EF = 2.35)
|ERWH (50 gal, EF = 0.90)
* NREL National Residential Efficiency Measures Database
† US Government Energy Guide Labels
Expected Annual Energy Savings by House Size
|Number of Bedrooms
||Average Daily Hot Water Usage (Gallons)
||Expected Annual Energy Savings (kWh)
||Annual Utility Bill Savings
||Return on Investment
||Payback Period (years)