Match the product family as well as the serial
Lochinvar’s own guide assigns different date systems to tank products and selected commercial water heaters or boilers. All rules here are labeled per maker; an independent source confirming each exact product boundary was not found.
| Product / format | Date fields | Example |
|---|---|---|
| Tank products, 2011 onward; 11 characters | Year, then week | 1142N012345: week 42 of 2011 |
| Older tanks; two letters and 6–7 digits | Year letter, then month letter | KJ1000130: September 1993 |
| Selected commercial products in 2015 | Week, then year | 411501213456: week 41 of 2015 |
| Same commercial family from 2016 | Year, then week | 162201213456: week 22 of 2016 |
The commercial list includes ARMOR, SHIELD, Copper-Fin and several boiler families. Check the exact model list on page 3 of the linked guide. The 2015 reversal does not apply to the eleven-character tank format.
Older tank year letters
The supported explicit table runs K = 1993, L = 1994, M = 1995, N = 1996, P = 1997, S = 1998, T = 1999, W = 2000, X = 2001, Y = 2002, Z = 2003, then A–H = 2004–2011 and J = 2012. The second letter uses A–M for January–December, skipping I. Earlier cycles are not inferred here.
Errors in the published guide
The commercial section calls its numeric code thirteen characters long but prints twelve-digit examples. Both lengths are accepted and the mismatch is disclosed. More seriously, some older single-letter month tables contradict the guide’s worked examples. Those styles are left undecoded; the tool does not choose a month from contradictory instructions.
Common questions
Why might one number produce two readings?
A numeric code can fit both a 2015 week/year layout and a later year/week layout. Both candidates are shown where they fit. Resolve the product and era from the model and any printed factory date.
Does the date prove warranty coverage?
No. The guide explains serial dates, but coverage depends on the product and applicable warranty. Ask Lochinvar using the full model, serial and installation records.
Where is the label?
Tank labels are commonly on the front or right of the jacket. Commercial locations vary by model; the guide gives specific locations. Read an accessible exterior plate without removing powered covers.
Worked examples
| Serial | Style | How it reads | Made | Example from |
|---|---|---|---|---|
1142N012345 | Tank products: year + week (2011 on), per maker | 11 = year ’11; 42 = week 42 of the year | Week 42 of 2011 (around October) | Lochinvar |
KJ1000130 | Older tank products: year + month letters, per maker | K = year letter (1993); J = month letter (September) | September 1993 | Lochinvar |
411501213456 | Selected commercial products: week + year in 2015, per maker | 41 = week 41 of the year; 15 = year ’15 | Week 41 of 2015 (around October) | Lochinvar |
162201213456 | Selected commercial products: year + week from 2016, per maker | 16 = year ’16; 22 = week 22 of the year | Week 22 of 2016 (around May) | Lochinvar |
Not affiliated with Lochinvar. Brand names describe decoder compatibility. Manufacture date is not installation date.
Sources
- Lochinvar: Warranty information by serial number, revision 21 (January 2021)Used for: Tank products: year + week (2011 on), per maker; Older tank products: year + month letters, per maker; Selected commercial products: week + year in 2015, per maker; Selected commercial products: year + week from 2016, per maker.