Brands › Rheem › R801VA ULN (UF/HZ)
Rheem R801VA100521MUA furnace filter size
This furnace takes a 19.25 x 25 filter (bottom (RXGF-CB external rack, upflow/horizontal) return) or a 15.75 x 25 filter (side (RXGF-CD external side-return rack, upflow)), 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 |
|---|---|---|
| bottom (RXGF-CB external rack, upflow/horizontal) | 19.25 x 25 | 1 |
| side (RXGF-CD external side-return rack, upflow) | 15.75 x 25 | 1 |
Where the filter goes
External filter rack accessory; "*Filter racks are shipped without filters." Furnace is not shipped with a filter.
The maker does not ship a filter with this furnace. The size above is the maker's recommended size at the furnace; if your home has a filter grille in a wall or ceiling, that grille sets the size instead.
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 | 21 in. |
|---|---|
| Airflow direction | upflow/horizontal (ultra low NOx) |
| Heat input | 100,000 BTU/hr |
| Efficiency (AFUE) | 80% |
| Model number note | Same furnace as Ruud R801VA100521MUA, per the maker's document. |
| Also sold as | Ruud R801VA100521MUA |
How to read a Rheem model number
Source
- Ruud R801V (UF/HZ) Ultra Low NOx Series spec sheet, Form G22-560 Rev. 1 (spec sheet, page 9): document. Read 2026-11-03.
- Rheem Endeavor Line SEER2 furnace brochure + spec sheet bundle (Form M11-6115/M11-6116 with G11-662..G11-678) (spec sheet (bundle of maker spec sheets), page 53): 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.