The ABC’s of Plumbing – Energy Factor

If you’re planning on replacing your old water heater, one of the most important things to consider is how efficiently it will produce hot water. To make it easier for consumers to compare water heaters and select the most energy efficient model, the US Department of Energy has developed a standard for residential water heaters, call the Energy Factor.

As with cars and Miles Per Gallon (MPG), the Energy Factor (EF) rates how efficiently a water heater uses its fuel source. When comparing standard products of the same fuel type, a water heater with a higher Energy Factor rating uses less energy, resulting in both energy and cost savings.

The Energy Factor is determined by performing a 24-hour simulated test on residential water heaters. During the test a measured number of gallons of water are drawn from the water heater in six equally spaced draws that begin one hour apart. After the beginning of the last draw a standby period of 18 hours follows.

The result of the test is expressed as a decimal. For example, a gas water heater with an energy factor rating of 0.5 means it’s 50% efficient. It will use 50% of the gas to heat the water, while the remaining 50% is heat going out the exhaust flue.

When comparing water heaters it’s important to consider the fuel source. While an electric water heater may have a higher EF rating, electricity is typically more expensive than natural gas. Also, be sure to compare the EF for the same type of water heater, the EF rating for tankless and hybrid water heaters is measured differently than it is for conventional tank water heaters.

Have questions about choosing the best water heater for your home? Call ABC Southwest Plumbing & Air Conditioning.