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 the tank was built to operate in the “non-simultaneous” mode, meaning only one element will energize at a time (standard for residential water heaters). Anytime anyone is dealing with numbers and letters in determining data, mistakes and misinterpretation are bound to happen. For this reason if you find during your research that we may have erred please contact us. In addition perhaps you have come across a brand, model or serial number format that we have not addressed. Rheem Manufacturing ranks as the global leader in the manufacture of high-quality, sustainable, and innovative water heaters, tankless water heaters, air conditioners, furnaces, pool heaters, and HVAC systems for residential and commercial applications, and is a full member of AHRI, the Air-Conditioning, Heating, & Refrigeration Institute. First, determine the type of equipment from the two categories shown below. The photos and diagrams will help you locate the model and serial numbers of your equipment, if they are not found on your original warranty or sales invoice.
You can determine how old your residential water heater is by looking at and decoding data on the water heater’s label.
First, locate the manufacturers label with the serial number on the side of your unit. This sticker is usually around any warning labels and the energy guide. Check to see if the installation date is noted on the sticker. If not, then write down your serial number as it usually indicates the year and month of manufacture of the water heater. Each manufacturer uses different formats and you need to de-code the water heater serial number. Read below how to determine the age of your unit.
Rheem or Ruud
ex. 1209D1234 (MMYYPnnnn) = December 2009
MM = month of manufacture
YY = year of manufacture
P = plant identifying code
nnnn = a consecutive serial number for your individual unit
AO Smith and American
ex. 9705123445 (YYWWxxxxxx) = 1997, 5th week (early February)
YY = month of manufacture
WW = year of manufacture
Bradford White
ex. BH6511396 (YMxxxxxxx) = B=2005 & H=August
The Bradford White rating plate is the most difficult to decode.
Ruud Model Number Identification
The year of manufacture is noted by the first letter of the serial number, the month is the second letter. The decoding is based on the following format (also see chart below):
Year Decoder: G = 1990; H = 1991; J = 1992; K = 1993; L= 1994; M= 1995; N= 1996; P= 1997; S= 1998; T= 1999; W= 2000; X= 2001; Y= 2002; Z=2003; A= 2004; B=2005; C=2006; D=2007
Month Decoder: A= JAN; B=FEB; C=MAR; D= APR; E=MAY; F= JUNE; G=JULY; H= AUG; J= SEPT; K=OCT; L= NOV; M= DEC.
Note: Bradford White uses a 20-year letter designation rotation in serial numbers shown in the chart below. Therefore, please be aware that water heaters manufactured 20 years apart will have the same serial number “letter year” designation.
Click image to enlarge.
Ruud Model Numbers Explained
For a complete water heater dating chart visit www.nachi.org/water-heater-dating-chart.htm
Ruud Model Number Search
If your Tucson water heater is 10 years or older you should consider replacing it before it fails and potentially could cause damage.