Read the label on your filter or unit
Two common questions, answered from the makers' own documents: what size is this filter really, and when was this unit built?
Filter sizes
| Page | What you get |
|---|---|
| 16x25x1 | Actual size from Filterbuy and Glasfloss |
| 20x25x1 | Actual size from Filterbuy and Glasfloss |
| 16x20x1 | Actual size from Filterbuy and Glasfloss |
| Nominal vs actual | Why the printed size is not the real size |
| AprilAire 2210 → 213 | Filter number, nominal and actual size |
| AprilAire 2410 → 413 | Filter number, nominal and actual size |
Manufacture-date codes
Manufacture date, not install date or warranty status. A date code tells you when the maker built the unit. It does not tell you when it was installed, whether any warranty applies, or what condition the unit is in.
| Maker | Rule in one line |
|---|---|
| Rheem (water heaters) | Digits 1–2 month, 3–4 year |
| Bradford White | Letter 1 year (two possible years), letter 2 month |
| A. O. Smith | Digits 1–2 year, 3–4 month or week |
| Goodman and Amana | Digits 1–4 YYMM |
We add a maker only when it publishes its own rule. Carrier and Trane are not here yet. We did not find a Carrier page that explains its date code, and the Trane page we found covers light commercial units only.
How we work
- Every number links to the maker's own page or PDF, with the date we read it.
- We copy sizes and rules as printed and label our own arithmetic.
- Where a code could mean two dates, we show both.
More on the method page.