I use the document that some kind soul made up for dating HVAC equipment and then posted on this board. For International Comfort/Comfortmaker/Heil, it says letters represent months, skipping “I”.
Everyone I see is an “L” (two today). Are they all made in November (L=11th month)? Or is the chart wrong?
Thanks
Bruce
Dumb question. Are you using the first letter? That what I have too. First letter for the month (skipping I) first two digits are the year.
I appreciate you telling me dumb question. Thanks for your concern.
Next?
I mean I was the one asking the dumb question. Sorry for the mis understanding. I thought you were probably using the first letter reference, just thought I’d ask. 
sorry for the snappy response. i’m working on one report and have another to finish before bed. can you say slightly stressed? 
the last 10 houses that i’ve done that have had ICP products, have all had “L” as the first letter in the serial number. too weird. Based on today’s, I’m now wondering if the first 2 or second 2 numbers represent a week. I’ll have to look back at photos to see if that lines up or not.
once again, i’m sorry for the terse response.
B
If that “L” is the first digit in the serial number, then that is the manufacturing plant. The next two digits (second and third digit in the number) will give you the year. So it wouldn’t be unusual for you to find that all the furnaces in your service area were manufactured at the same plant, hence all of them beginning with the letter “L”.
That would make total sense. At first I thought it was just coincidence, but then after so many units, I’m beginning to wonder.
How did you find out that information?
The document that I downloaded was somewhere on this MB. So if what you’re saying is true, and I believe it probably is, we need to get the word out that the first letter is not the month for ICP/Heil.
Bruce
PS they’re hvac units:)
Corrected. Thanks.
Three decades of research and data accumulation.
Sometimes it could be for the larger manufactures who have been manufacturing for eons. Back when labor unions were extremely strong, whenever there was a strike against one manufacturer, that manufacturer would try to outsource as much of its business as possible to other manufacturers in an effort to (1) work with the union and strikers, and (2) not interrupt their business so that they had a more powerful position from which to work with the union and the strikers. Consequently, sometimes you’ll find a strange numbering system that doesn’t match the brand at all. If one were to go back to the newspapers for the time period, one would probably find that there was a strike somewhere. Dig a little deeper and one could find out that ABC Company was having its products built by DEF Company. Sometimes DEF would use its own coding system, sometimes, in deference to the nice contract with ABC, would use ABC’s coding system.
At other times, ABC merged with or was puchased by DEF, but DEF kept the ABC brand name due to ABC’s brand recognition. But they changed the ABC coding to that of DEF coding, so you’ll have ABC brand with DEF coding. That’s why it’s important to keep track of mergers, acquisitions, etc., and if the coding doesn’t match what is typical, check the coding of the other companies involved in the merger or acquisition.
So don’t throw anything away. Just keep accumulating data and use those clues that property inspectors are famous for to put two and two together to get four.