Older AO Smith water heater serial number

[Joshua L. Frederick]

Numbers aren't jiving with my codes. Would it be '87 or '78?

Serial #: 87C-K-78-44070

THANKS.

[Mark Nahrgang]

I agree, that serial number doesn't look right. Do you have a photo of the label?

[GARY L. RUSK]

1987

AO Smith - Can be confusing; digits may be comprised of letters & numbers. May be one, two, or no letters.
If two letters first, next two numbers are year.
If one letter first, followed by two numbers and another letter, next two numbers are year.
If one letter first, next two numbers are year, providing no letter follows.
If two numbers first, this is year.

Gary

[Russel Ray]

Gary's on top of it.