The serial number includes the part number, year, day, site, and unit number of the day. Below are two examples of serial numbers and how to interpret it.
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Model and Serial Number Location
There are a few different places you may find the model and serial number.
1. On the decal located on the underside of the salt lid.
2. Under the top cover on the bottom of the front faceplate (2800, 3700, 3702 & 2802)
3. On the back of the bobble head cover (on some filters or basic models).