Brands › Rheem › RGRA/RGRB (Classic 90 Plus upflow)
Rheem RGRA-04EMAES furnace filter size
This furnace takes a 15.75 x 25 x 1 filter (single/any (factory permanent filter) return) or a 15.75 x 25 filter (bottom (RXGF-CB external rack) return) or a 15.75 x 25 filter (side (RXGF-CA external side rack) return), depending on where the return air comes in.
The maker lists width and height only. Most filter racks next to a furnace hold a 1-inch filter; a separate filter cabinet usually holds a 4- or 5-inch one. Check the thickness printed on the edge of your old filter before you order.
Every filter option for this model
| Where return air enters | Filter size (inches) | How many |
|---|---|---|
| single/any (factory permanent filter) | 15.75 x 25 x 1 | 1 |
| bottom (RXGF-CB external rack) | 15.75 x 25 | 1 |
| side (RXGF-CA external side rack) | 15.75 x 25 | 1 |
Where the filter goes
Factory "STANDARD, HIGH VELOCITY PERMANENT FILTER" inside the furnace (spec features: "Molded permanent filters"); optional external racks RXGF-CB/CA "shipped without filters. Filters shipped with furnace may be used or a suitable 1" filter."
The maker ships a filter with this furnace.
How often to change it
General guidance, not from the maker's table: 1-inch filters every 1 to 3 months; 4- and 5-inch filters every 6 to 12 months. Change sooner with pets, smoking or construction dust.
About this model
| Cabinet width | 17.5 in. |
|---|---|
| Airflow direction | upflow (90 Plus) |
| Heat input | 45,000 BTU/hr |
How to read a Rheem model number
Source
- Rheem RGRA/RGRB Series spec sheet, Form G11-532 (spec sheet, page 4): document. Read 2026-11-03.
- Rheem RGRA/RGRB (Classic 90 Plus) spec sheet, Form G11-450 Rev. 15 (spec sheet, page 3): document. Read 2026-11-03.
Check that the model number on your furnace label matches, and compare with the size printed on your old filter. If they differ, go by the filter that fits your rack.