Water Heater Model Numbers & Rating Plates

Sometimes, finding your water heater model number can be tricky. But, all water heaters have a Rating Plate that lists important data such as the model and serial numbers, manufacturing company’s name, length of warranty, wattage of elements installed (on electric models), gallon capacity, input BTU rating (gas models), and more.

You can determine the age of our unit by de-coding the water heater serial number. Some manufacturers make it easy by incorporating the month and year built into the first 4 digits of the serial number. For instance, the picture below shows that this Rheem water heater was manufactured in December of 1991 (1291). Other manufacturers use different formats, but in a similar fashion.

A.O. Smith Model Numbers

AO SMITH rating plates look a little different, but have all the same info. Their date de-coding is a little different.

American Water Heater Model Numbers

American water heater rating plate, with close up below.

Above is a close up of the Bradford White rating plate. This is a 40 gallon electric water heater, model number MI40L6DS13, manufactured in June of 2002. It comes equipped with 4000 watt elements. Note the “Maximum Watts” at 4000, this means this tank was built to operate in the “Non-simultaneous” mode, meaning only one element will energize at a time (standard for residential water heaters). It is designed to operate with a maximum of 150 PSI water pressure, but was tested to 300 PSI at the factory for your safety (a Federal Standard!).