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Decoding Hot Water Heater Ratings and Efficiency Labels

May 30, 2023
An illustration of a water heater sporting a five-star energy efficiency rating tag.

Making Educated Purchasing Decisions

  • When it comes to purchasing hot water heaters, understanding the energy efficiency ratings and energy efficiency labels is essential.
  • These ratings and labels provide valuable information which will help consumers to make educated decisions.

Most water heaters use more energy than your refrigerator, clothes washer, dishwasher, and dryer combined! All these appliances represent 20-25% of your home’s energy.

Switching to a high energy efficient hot water heater will help you use 70 % less energy than a standard model.

  • ENERGY STAR is the trusted symbol for energy efficiency. It helps us save money and protect the environment through efficient products and practices. 

The ENERGY STAR label is known to help:

  • Reduce greenhouse gas emissions and other contaminants caused by the inefficient use of energy
  • Make it easy for consumers to identify the best possible and sensible choice

Energy Star Program:

The Energy Star program, established by the U.S. Environmental Protection Agency (EPA), sets energy efficiency standards for various appliances. An Energy Star label indicates that it meets or exceeds the program strict efficiency requirements. It will guarantee a reduced energy consumption and lower operating costs.

Energy Star Label:

The Energy Star label provides important information about a water heater’s efficiency. It typically displays the annual consumption in kilowatt-hours (kWh), which helps estimate the operating costs. The label usually includes details such as:

  1. the model number
  2. UEF rating
  3. the estimated annual energy cost savings compared to standard models.

UEF Ratings: energy efficient products

UEF (Uniform Energy Factor) ratings provide a standardized measure of energy efficiency for different types of water heaters.

The UEF ratings take into account factors in order to provide a more accurate representation of the overall efficiency:

  1. heat loss
  2. standby energy loss
  3. cycling losses

Higher UEF ratings indicate better energy efficiency.

Types of Water Heaters:

Different types of units have specific ratings and efficiency considerations, here they are:

  • Storage Tank: These traditional electric water heaters store and heat a large volume of water on a steady basis. Look for higher UEF ratings, as they indicate better efficiency.
  • Heat Pump : These innovative systems use electricity to move heat from the surrounding air to heat the water. Heat pump water heaters have UEF ratings that reflect their overall efficiency. They are known for significant energy savings compared to standard electric models.
  • Tankless : These units heat water on-demand, providing hot water whenever needed. They have flow rate ratings, measured in gallons per minute (GPM), which indicate the volume of hot water they can deliver. Efficiency ratings for tankless water heaters are expressed as UEF.
  • Rheem performance of all four is rather remarquable.

Water Temperature and Flow Rate:

Water heaters have specific temperature and flow rate capabilities, which can impact their energy efficiency. It’s important to consider your hot water needs when selecting a water heater. If you have a high demand for hot water, choose a model with a higher flow rate. You will make sure to have enough hot water supply.

Other Considerations:

In addition to efficiency ratings and labels, there are two important factors to consider:

  1. the warranty period
  2. the expected lifespan of the water heater

Most water heaters have a lifespan of around 10 to 12 years. Some models may offer longer warranties, indicating higher quality and durability. Installing a Corro-Protec powered anode will considerably prolong the lifespan of your heater.

In addition, consider the heating elements or heat exchangers used in the water heater. Look for models with advanced technology that improves heat transfer efficiency and reduces energy consumption.


Understanding the energy efficiency ratings and labels associated with water heaters is important when making purchasing decisions. The Energy Star program provides a reliable measure for energy efficiency, while UEF ratings help determine a water heater’s overall efficiency.

You can choose a water heater that meets your household’s hot water needs while minimizing energy costs. The following information is important to consider:

  1. the type of water heater,
  2. UEF ratings,
  3. water temperature,
  4. flow rate,
  5. other important factors indicated above

Remember to look for the Energy Star label, compare UEF ratings, and evaluate the specific requirements of your household.

Prepare for a clean energy future, as our energy supply gets cleaner and more renewable every day.


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