About UnitAgeCheck

UnitAgeCheck is an independent tool for homeowners. It isn't affiliated with any manufacturer.

How we decode serial numbers

Each brand's date-code format is built from the manufacturer's own documentation (service manuals, spec sheets, warranty guides) and tested against known serial-and-date examples. Where a manufacturer doesn't publish an older format, we only use it when several independent references agree, and we mark those results as corroborated rather than certain.

Brands currently supported: Bradford White, A. O. Smith, State, American Water Heater, Rheem, Ruud, Goodman, Amana, Daikin, Carrier, Bryant, Payne, ICP, Trane, American Standard, Lennox, York, Whirlpool, Navien, Rinnai.

Data sources

• Remaining life: typical ranges from NAHB/Bank of America's Study of Life Expectancy of Home Components, InterNACHI's life-expectancy chart, and DOE Energy Saver. Adjusted using USGS water hardness and NOAA heating/cooling degree days.
• Efficiency: DOE Compliance Certification Database and ENERGY STAR certified product data.
• Federal efficiency minimums: when we can't find a unit's rating, we show the lowest efficiency U.S. law allowed when it was made ("built to at least"), not its actual rating. Our dataset covers central air conditioners and heat pumps (SEER/HSPF from 1992, SEER2/HSPF2 from 2023, including the 2015 and 2023 Southeast and Southwest rules), gas furnaces (AFUE from 1992), and gas and electric tank and tankless water heaters (EF from 1990, UEF from 2017). It's built from the Code of Federal Regulations (10 CFR 430.32, current and past editions) and DOE final rules in the Federal Register, checked 2026-10-15. Rules that were adopted but never took effect, like the 2011 northern furnace standard a court vacated in 2014, are not applied.
• Refrigerant (air conditioners and heat pumps): read from the model number when it states one. Otherwise we estimate it from the year the unit was made, using the EPA's R-22 phaseout dates (new R-22 equipment ended January 1, 2010; R-22 production and import ended January 1, 2020) and the EPA's AIM Act rules for new residential systems (January 1, 2025). That is a guess from legal dates, not a reading of the unit, and years close to a cutoff are marked uncertain. Each date links to the EPA or Federal Register page, checked 2026-10-15.
• Recalls: U.S. Consumer Product Safety Commission (updated 2026-10-16).
• Energy prices: U.S. Energy Information Administration, 2025.
• Repair and replacement costs: published ranges from national cost guides, cited on each result.

Limits

Remaining life is a typical range for the population of units, not a prediction for yours. Always confirm the date on the data plate or with the manufacturer, and get a licensed contractor's opinion before deciding on a repair or replacement.