Updated October 2026.
Short answer: the Buck Model 91 and Buck Model 81C are both catalytic wood stoves rated at 80 percent efficiency, both include a blower and an ash pan, and both install freestanding or as a masonry fireplace insert. The Model 91 is the bigger stove: a 4.4 cu ft firebox rated for 1,800 to 3,200 square feet, on an 8" flue. The 81C is Buck's bay-front stove: a 3.0 cu ft firebox rated for 1,600 to 2,700 square feet, on a 6" flue, and it is approved for mobile homes, which the Model 91 is not.
Side by side
| Model 91 | Model 81C | |
|---|---|---|
| Heats (Buck's rating) | 1,800-3,200 sq ft | 1,600-2,700 sq ft |
| EPA tested output | 14,206-62,745 BTU/h | 13,800-59,500 BTU/h |
| Firebox volume | 4.4 cu ft | 3.0 cu ft |
| Firewood length | 23" side to side, 22" front to back | 18" side to side, 20" front to back |
| Combustion and efficiency | Catalytic, 80 percent | Catalytic, 80 percent |
| Flue size | 8" | 6" |
| Stove size (W x H x D) | 34-1/4" x 23-3/16" x 28-7/8" | 29" x 24" x 23-3/4" |
| Weight | 626 lbs | 460 lbs |
| Blower | Included, factory-installed variable speed | Included |
| Ash pan | Included | Included |
| Minimum fireplace opening for an insert (W x H x D) | 31-3/4" x 23-1/2" x 15-1/2" | 29" x 24-1/2" x 14" |
| Insert clearances | 30" to mantel, 20" to sidewall | 21" to mantel, 12" to sidewall |
| Minimum hearth pad, freestanding (W x D) | 50" x 54" | 33" x 48" |
| Freestanding clearance to combustibles | 16" corner, 23" rear, 24" side, tested with double-wall pipe; no close-clearance shield option | 16" corner, 23" rear, 25" side; 12" corner, 16" rear, 12" side with Buck's close-clearance shields and single-wall pipe |
| Mobile home approved | No | Yes |
Ratings, sizes and clearances from the Buck Stove 2026 wood stove catalog. Hearth pad sizes are Buck's minimums for vertical vent installations. The owner's manual for your unit governs the installation, so confirm every figure against it before you build a hearth or order pipe.
How to choose
- Square footage. Between 1,800 and 2,700 square feet, both are rated for the job, and the 81C is the more compact stove. Below 1,800 square feet, the 81C is the closer fit. Above 2,700 square feet, or to heat a whole large house from one stove, the Model 91 has the larger firebox and the higher output.
- Your flue. The 81C uses a 6" flue and the Model 91 uses an 8" flue. If your chimney already has a 6" liner, the 81C matches that size, as long as the liner meets the owner's manual. For a Model 91 in a masonry chimney, Buck's 8" Chimney Connector lets the stove accept a flexible chimney liner, and the 8" Offset Adapter handles a rear or offset exit. Both are listed on the Model 91 page.
- Your fireplace opening (insert installs). The Model 91 needs an opening at least 31-3/4" wide, 23-1/2" high and 15-1/2" deep. The 81C needs at least 29" wide, 24-1/2" high and 14" deep. Measure before you choose.
- Floor space (freestanding installs). The Model 91 needs a hearth pad of at least 50" x 54". The 81C needs at least 33" x 48", and its clearances to combustibles shrink to 12" side and 16" rear with Buck's close-clearance shields and single-wall pipe.
- Mobile home. Of these two, only the 81C is approved for mobile home installation.
- Log length. The Model 91 takes 23" logs side to side. The 81C takes 18" side to side or 20" front to back.
What catalytic means for both
A catalytic combustor burns off smoke that would otherwise go up the chimney. That is how both stoves reach 80 percent efficiency, and it allows longer, lower burns between loads. The combustor needs periodic inspection and cleaning on the schedule in the owner's manual, and like any catalytic combustor it wears over time and is eventually replaced.
The 81C is Buck's 2026 catalytic version of the earlier Model 81, with a larger 3.0 cu ft firebox.
Questions buyers ask
Which heats more space?
The Model 91. Buck rates it for 1,800 to 3,200 square feet, against 1,600 to 2,700 for the 81C.
Can either go in a mobile home?
The 81C can. The Model 91 is not approved for mobile homes.
Are the blower and ash pan included?
Yes, on both. On the Model 91 the variable speed blower is factory installed.
Do they qualify for the federal tax credit?
No. The federal credit ended for stoves placed in service after December 31, 2025. Read more about the tax credit.
What if my house is smaller?
Look at the Model 21 and 74C in our Buck Stove sizing guide.
Before you order
Both stoves ship free by freight from MyBBQDirect within the continental US, and the carrier calls ahead to schedule delivery. Each product page has the delivery details. Not sure which one fits? Call (708) 765-6925 with your square footage, flue size and fireplace opening, and we will check the numbers with you.
