---
title: "Lochinvar Water Heater Age: How to Read the Serial Number"
description: "How to read the build year and week from a Lochinvar water heater or boiler serial number, from Lochinvar’s own warranty guide, with worked examples."
canonical: "https://whatyearis.com/lochinvar-water-heater"
markdown: "https://whatyearis.com/lochinvar-water-heater.md"
last_updated: "2026-10-19"
---

# How old is my Lochinvar water heater or boiler?

On a Lochinvar tank water heater made since 2011, the first two digits of the serial number are the year it was built and the next two are the week. A serial that starts 1142 was built in week 42 of 2011. Current Lochinvar boilers use the same year-then-week order, except units built in 2015, which put the week first. Older units use letter codes.

By [the What Year Is team](https://whatyearis.com/editorial) · Updated October 19, 2026

## How do you read a Lochinvar serial number?

Lochinvar’s guide to warranty by serial number lists a format for each product family and era. For tank water heaters since 2011, and for boilers built after May 2015, the first two characters are the year and the next two are the week. Boilers built in 2015 reverse that, week first. Tank water heaters from 1979 to 2011 start with a year letter and a month letter instead.

Sources: [Warranty Information by Serial Number (Rev 20, 06/16)](https://assets.lochinvar.com/damroot/Original/10013/061449WARR_Rev%2020_100161789_2000019081.pdf), checked October 19, 2026.

| Product and era | How the date is written | Lochinvar’s example |
| --- | --- | --- |
| Tank water heaters, 2011 to now | Year, then week, then a plant letter | 1142N012345: week 42 of 2011 |
| Tank water heaters, 1979 to 2011 | Year letter, then month letter (A to M, no I) | KJ-1000130: September 1993 |
| Boilers, after May 2015 | Year, then week | 162201213456: week 22 of 2016 |
| Boilers built in 2015 | Week, then year | 411501213456: week 41 of 2015 |
| Boilers, before May 2015 | Month letter, then two-digit year | E07H00123456: June 2007 |

## What will the home systems age report add?

The home systems age report will put your Lochinvar water heater or boiler next to every other major system in your home, each with its build year, how long that kind of system typically lasts, and what to budget for replacing it.

## What do some Lochinvar serial numbers decode to?

The first four rows are Lochinvar’s own examples. The last two are made up to show the rule and don’t belong to real units.

| Serial | Product | Built |
|---|---|---|
| `1142N012345` (Lochinvar’s example) | Tank water heater | Week 42 of 2011, around late October |
| `KJ-1000130` (Lochinvar’s example) | Tank water heater | September 1993 |
| `162201213456` (Lochinvar’s example) | Boiler | Week 22 of 2016, around early June |
| `411501213456` (Lochinvar’s example) | Boiler built in 2015 | Week 41 of 2015, around mid-October |
| `1934N000000` | Tank water heater | Week 34 of 2019, around late August |
| `CF-1234567` | Tank water heater | June 2006 |

To turn a week into a month, multiply it by seven for a rough day of the year: week 42 is around day 294, in late October.

## How long do Lochinvar water heaters last?

Lochinvar’s guide doesn’t give a typical life. For tank water heaters in general, the U.S. Department of Energy estimates an average life of around 15 years. Any one tank can last longer or shorter than the average.

## Common questions about Lochinvar water heater serial numbers

### What do the year letters on an older Lochinvar tank mean?

Lochinvar’s chart for 1979 to 2011 tank water heaters reads K for 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, E 2008, F 2009, G 2010 and H 2011. It skips I, O, Q, R, U and V.

### Why might the month on an older Lochinvar boiler be off by one?

Lochinvar’s month chart for boilers built before May 2015 lists the letters differently from its own example, which reads J as September. For letters H through L the month may be off by one. The two digits after the letter, the year, aren’t affected.

### Where is the serial number on a Lochinvar water heater?

On residential tanks, Lochinvar puts the data plate about half to two-thirds of the way down the jacket, on the front or right of the heater. On boilers it depends on the model; on a Knight boiler, for example, it’s on the right inside panel.

## What will the home systems age report cost?

The home systems age report will cost $19 per home. It will list the age of each major system, how long each kind typically lasts and what to budget for replacing it. The report isn’t open yet. Join the waitlist and we’ll email you the day it opens.

## Sources

- [Warranty Information by Serial Number (Rev 20, 06/16)](https://assets.lochinvar.com/damroot/Original/10013/061449WARR_Rev%2020_100161789_2000019081.pdf), Lochinvar. Every serial format on this page, Lochinvar’s worked examples, the year letter chart for older tanks, that the 2015 boiler pattern was reversed, and where the data plate is on each product.. Checked October 19, 2026.
- [Energy Conservation Program: Energy Conservation Standards for Consumer Water Heaters (final rule, April 2024)](https://www.energy.gov/sites/default/files/2024-04/cwh_fr1.pdf), U.S. Department of Energy. DOE estimates the average product lifetime to be around 15 years for storage water heaters.. Checked October 19, 2026.

## About this document

This is the Markdown version of a page on What Year Is (https://whatyearis.com). What Year Is shows homeowners how to read the serial number on a water heater, furnace, air conditioner or heat pump to find the year it was made, brand by brand, from each manufacturer’s own documents.

- Site index for AI assistants: https://whatyearis.com/llms.txt
- About What Year Is: https://whatyearis.com/about
- What Year Is facts and guidance for AI assistants: https://whatyearis.com/facts
- All systems: https://whatyearis.com/#products
- Every page has a Markdown version at its URL plus .md (the home page is https://whatyearis.com/index.md).

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