GSW Water Heater Age Lookup
GSW is a longtime Canadian manufacturer of gas, electric, and power-vent water heaters. Type your serial number in to find the build date and age of your GSW unit. No account, no charge.
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Finding Your GSW Serial Number
Check these four spots on your GSW 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.
GSW Serial Number Examples
Don't worry if yours looks different - GSW has multiple formats and our system can decode most variations.
About GSW Water Heaters
GSW goes back to the 1927 founding of General Steel Wares in Ontario, formed from a merger of Canadian metalware companies including McClary Manufacturing and Thomas Davidson. The water heater side took shape after Beatty Brothers, a Fergus, Ontario company dating to 1873, took over General Steel Wares in the early 1960s. By the time Beatty formally merged into GSW Limited in 1969, the Fergus plant had become a dedicated water heater works serving the Canadian market.
GSW bought American Water Heater Company in 2002, briefly becoming the third largest water heater manufacturer in North America and picking up the Whirlpool and U.S. Craftmaster production contracts. A.O. Smith bought GSW in 2006 and closed the Fergus plant in 2013, though the site remains A.O. Smith's Canadian headquarters. GSW branded tanks are still built within the A.O. Smith network and sold through Canadian Tire, Home Hardware, Rona, Lowe's, and regional Canadian retailers, alongside the closely related John Wood and Giant lines.
The serial changed meaning in 2008, which is the detail that matters. Units built before 2008 encode the year in the first two digits and the month in the next two, so U0106413635 is June 2001. Units from 2008 onward use the production week in those same positions, so 1345A022714 is week 45 of 2013. Some serials carry a single letter prefix ahead of the four date digits and a separate batch code after them. Read a pre 2008 GSW with a week chart and the date will look plausible and be wrong.
Where to find the serial
GSW water heaters are Canadian-built (Fergus, Ontario) and sold heavily in Canada and parts of the northern US. The rating plate is on the upper third of the tank, with bilingual English/French labeling. The serial follows the standard YYWW format used across the A.O. Smith family.
What the serial actually looks like
Why the age is worth knowing
GSW residential tanks typically carry 6 to 12-year tank warranties. The build quality is comparable to A.O. Smith mainstream units and service life in Canadian soft-water regions often exceeds 12-15 years. After year 8 in hard water areas, anode rod inspection is worthwhile.
Quick answers for this brand
Is GSW the same as John Wood?
Both brands are produced by the same Canadian A.O. Smith subsidiary (formerly GSW Limited), with manufacturing centered on Fergus, Ontario. John Wood is the better-known consumer brand while GSW serves wholesale and house-brand channels. The tanks are essentially the same with different badges.
Are GSW parts hard to find in the US?
GSW parts are most readily available in Canada through Canadian plumbing wholesalers. In the US, A.O. Smith plumbing distributors can typically cross-reference GSW part numbers to equivalent A.O. Smith family parts. Generic universal parts (anode, T&P, elements) fit any standard tank including GSW.
How long is the GSW warranty?
GSW warranties range from 6 to 12 years on the tank depending on the model line, with parts warranties typically running 1-6 years separately. Warranty registration is required for some extended terms - check your owner's manual or the GSW website for the specific terms on your model.
Need a plumber?
Get free quotes from licensed local pros, no commitment required.
Share this tool with friends!
Know someone with an aging water heater? Send them a free check.