What is the Uniform Energy Factor of my water heater?

Uniform Energy Factor or UEF is the standard measure of a water heater’s overall efficiency. Basically, the higher the UEF rating, the more efficient the water heater. (The former measurement EF is no longer used and cannot be directly compared to UEF. To find your water heater’s UEF rating, go to the My Water Heater Information page and enter your model or serial number. If you need help finding them, there are instructions there as well. Once you enter your water heater’s model number, you’ll find the manuals and documentation for your heater. The UEF will be listed in the Specifications document.