Lochinvar Water Heater Age Lookup
Lochinvar is a go-to name for residential and commercial water heating. Enter your serial number to find the exact build date and age of your Lochinvar unit. No cost, no account.
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Finding Your Lochinvar Serial Number
Check these four spots on your Lochinvar water heater
Common Locations
What to Look For
- White or metallic manufacturer sticker
- Labeled "Serial No." or "S/N"
- Typically 8–12 characters long
- Usually near the model number
Can't find it? Try removing access panels or checking behind the temperature dial.
Lochinvar Serial Number Examples
Don't worry if yours looks different - Lochinvar has multiple formats and our system can decode most variations.
About Lochinvar Water Heaters
Lochinvar has been in business since 1939, began in Chicago, and is now headquartered in Lebanon, Tennessee. It has been a division of A.O. Smith since 2011 and serves as the group's specialist in high efficiency commercial and hydronic equipment. You are more likely to meet a Lochinvar in a mechanical room than in a house, because engineers specify them for buildings.
The catalog is boilers and commercial water heaters rather than ordinary tanks. KNIGHT covers modulating condensing boilers, ARMOR is the condensing water heater line for commercial loads, Copper-Fin uses finned tube heat exchangers for high recovery, NOBLE is the combi boiler for smaller hydronic systems, and SHIELD covers commercial storage. Heat exchanger coverage is quoted separately from the rest of the appliance, and terms shift with how the unit is applied, so the warranty on the paperwork depends on the installation as much as the model.
Lochinvar identifies equipment by model prefix rather than by a SKU catalog, so the prefix tells you the family and the feature set without a lookup table. Serials from 2011 onward use the A.O. Smith convention, a two digit year followed by the production week, sometimes with a plant letter in the middle, so 1519A12345 is week 19 of 2015. Earlier units used a four digit month and year code instead.
Where to find the serial
Lochinvar water heaters and boilers have the rating plate on the side or front of the unit. The serial is typically a long alphanumeric string and is also printed on a separate barcode label inside the access panel. Lochinvar makes both tank and tankless residential units plus a large commercial line.
What the serial actually looks like
Why the age is worth knowing
Lochinvar residential gas units typically carry around a 6-year tank warranty, while commercial units vary and many run far longer in service. Lochinvar's strength is high-efficiency condensing technology - the stainless or copper heat exchanger is usually the most expensive long-term service item (and is covered separately from the tank), so descaling and combustion maintenance pay off significantly.
Quick answers for this brand
How do I tell a Lochinvar water heater from a boiler by the model number?
Look at the model prefix. Water heater families end in W (for example AW ARMOR, EJW residential gas, CW/EW/RW/IW/CF copper-tube, CG/CL commercial gas), while boiler families end in B (for example KB KNIGHT, FB/FTXL CREST, PB POWER-FIN, NKB/NKC NOBLE combi). A boiler heats water for space heating, not domestic hot water, so if your unit is a boiler this tool's water heater results will not apply.
Why won't my newer Lochinvar serial decode?
Lochinvar's newest units use a long 13-digit serial that the company does not publish a public date code for, so it cannot be reliably decoded here. Use the manufacture or production date printed directly on the rating plate instead - it is the most accurate source for those units.
Is Lochinvar mainly for commercial?
Lochinvar has historically been a commercial-leaning brand, especially known for the Knight, Crest, and FTXL boiler series. Their residential line (Squire, Sit-Lo) is smaller but well-regarded. Many residential installations are actually light commercial units sized for large homes.
Is Lochinvar related to A.O. Smith?
Yes - Lochinvar has been owned by A.O. Smith Corporation since 2011 and operates as a separate brand focused on commercial and high-efficiency residential markets. Manufacturing is in Lebanon, Tennessee. The Lochinvar serial format is distinct from A.O. Smith's standard YYWW residential format.
Where do I get parts for a Lochinvar Knight?
Lochinvar parts route through the A.O. Smith commercial distribution network and a strong network of authorized Lochinvar service partners. The factory tech support line (615-889-8900) is the best starting point for older units or unusual model variants.
Need a plumber?
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Share this tool with friends!
Know someone with an aging water heater? Send them a free check.