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 and Air Conditioning.

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