Replacement Electric Water Heater

If you have an older electric water heater, a new high-efficiency model can save a significant amount of money for years to come. Next to heating or cooling, water heating is usually the largest energy user in the home.

High-efficiency electric water heaters usually have higher levels of foam insulation, some as high as R-19. This is especially important if your water heater is located in an unconditioned area.

There has been no significant improvement in electric elements. Electric resistance heating elements in your tank (standard electric water heating) transfer virtually 100% of their energy to the surrounding water as heat, and it is difficult to improve on 100%. There are higher-efficiency heat pump water heaters which operate at an efficiency of over 100%, and often over 200%. They transfer heat from the surrounding air, ground, or well water to the water in the tank. Check with your contractor or local electric company to see if a heat pump water heater is right for you.

If you use central air conditioning, consider a waste heat recovery unit, which reclaims the heat given off by the outdoor unit of your air conditioner to heat water. When the air conditioner is not running, the standard heating elements serve as a back-up. Ask your heating and cooling contractor to see if a waste heat recovery unit is right for you.

Water Heater Efficiency

The energy efficiency of a storage-type water heater is indicated by its Energy Factor (EF). This is a measure of the overall efficiency of a water heater. It is determined by comparing the energy supplied in heated water to the total energy consumption of the water heater. A higher Energy Factor indicates a more efficient water heater. The most efficient electric storage water heaters have Energy Factors between 0.94 and 0.96.

First Hour Rating

This is the amount of hot water that the water heater can supply in the first hour of operation. It is a combined measurement of how much water is stored in the water heater and how quickly the water heater can heat cold water to the desired temperature. Use this rating to compare hot water delivery capabilities of similar models.

What To Look For

The Federal Trade Commission (FTC) requires that all storage-type water heaters be labeled with an "EnergyGuide" label. This label shows (based on the national average cost of electricity) the estimated annual operating costs for that particular water heater. The label also shows how that particular water heater compares with all other comparable models. When purchasing a new electric water heater, look for the "EnergyGuide" label and purchase one with lower estimated operating costs.