Replacing Your Water Heater : Compare The EF Ratings Before You Decide


When it’s time to replace your water heater, there are more things to consider than price and capacity — like the EF.

The EF (energy factor) rating is established by U.S. Department of Energy to assist consumers in comparing different water heaters. All water heaters carry an EF rating, displayed prominently on the unit, regardless of size, brand, model or fuel. The energy factor will give you a

better idea of the energy efficiency of a water heater so you can get the most hot water for your money.

There are three criteria used to determine the EF:

  • Recovery efficiency: This is the measure of the unit’s ability to transfer heat from the fuel source to the water.
  • Standby losses: The percentage of heat lost per hour from the water compared to the stored heat in the water.
  • Cycling loss: The amount of heat the water loses as it circulates through the water heater.

Naturally, a higher EF rating is preferable to a lower one — but don’t assume that the unit with the highest EF is the best choice. A higher EF could mean higher operating costs.

The EF is important, but you should consider the other factors of the unit, such as:

  • The water heater’s ability to consistently produce an ample supply of hot water for your household.
  • Is the fuel source required by the unit available in your house?
  • What are the annual operating costs and how quickly will it give you a return on your investment?
  • How much hot water can the water heater produce in one hour (starting with a full tank full)?

When you need to replace your water heater, weigh all of the options and pay attention to the EF rating to ensure that your choice is the one that suits your budget the best.