Buck Stove Fireplace Insert Model 21 | Non-Catalytic, 28,901 BTUs (Covers 1,800 Square Feet) | Wood Burning with Heat Activated Blower | Black Door with 9" Faceplate Trim Kit

Why I chose the Model 21 insert

I live in a draft-prone, mid-century home with an existing masonry fireplace that looked good but did little more than siphon warm air up the flue. I wanted an insert that would actually heat the main floor without turning the living room into a sauna, and I didn’t want the complexity or maintenance of a catalytic unit. The Model 21 insert hit the sweet spot: a compact, non-catalytic stove rated for up to 1,800 square feet with a heat-activated blower and a traditional look that doesn’t fight my home’s style.

Installation and fitment

If you’re retrofitting an old fireplace, this insert is friendly to work with, provided you do your homework. I used a full-length, insulated 6-inch stainless liner—a best practice I’d recommend for safety and draft—and sealed the old damper area with a simple block-off plate to keep heat in the room rather than the chimney cavity.

The included 9-inch trim kit is more useful than it looks on paper. The frames can be cut to size, which let me scribe to my not-so-square brick opening and cover a couple of irregular grout lines cleanly. If your surround isn’t perfectly plumb, that adjustability saves you from awkward gaps. Take careful measurements of your firebox depth and lintel height before ordering; the stated coverage is accurate, but the better your measurements, the tidier the final result.

One practical note: the unit is not overly heavy compared to some larger inserts, but I still needed a second set of hands and a small dolly to get it into the firebox without scuffing the hearth. Plan your liner connection so you’re not wrestling with the collar from inside the stove body.

Heating performance

Once installed, the Model 21 insert does what a good insert should: it turns a decorative fireplace into a legitimate heat source. In my 1,600-square-foot main floor (semi-open plan, decent insulation), it maintained comfortable temperatures through a shoulder-season cold snap without the furnace cycling on. In deeper winter, it took the edge off enough that the central heat ran less often and at lower setpoints.

BTU ratings can be misleading in the real world, but with seasoned hardwoods and the blower running, this insert pushes steady, usable heat. If you’re trying to heat a true 1,800 square feet in a colder climate or a chopped-up floorplan, expect to do it with frequent tending and strategic placement of a box fan to move air down hallways. In compact or well-insulated spaces, it’s right-sized and impressively effective.

Burn characteristics are what I expect from a modern, non-catalytic firebox. Once the stove body is up to temperature, you can see the secondary combustion working across the top—clean flames through the perforated tubes that cut down on visible smoke and wring more heat from each load. I’d call the firebox “modest.” It’s happiest with shorter splits and careful stacking. You’ll get solid evening burns, but true overnight heat without a reload is ambitious. Plan on tending every few hours if you want steady, high output.

Blower and noise

The heat-activated blower is a highlight. It kicks on automatically when the stove is hot enough and shuts itself down as the fire wanes, which is exactly how an insert blower should behave. On my unit, the noise is a low, even hum—audible in a quiet room but not conversation-killing. I’ve heard louder built-in blowers on bigger inserts. If you’re sensitive to vibration, a thin foam pad under the surround or a quick check that the blower housing isn’t touching the firebox skin will keep resonance in check.

Moving air is crucial for inserts, and the blower makes a real difference in how quickly heat spreads beyond the hearth. Without it, the stove still radiates nicely, but the blower increases the effective throw of the heat and helps even out room temperatures.

Controls and daily use

The air control is straightforward and responds predictably. Start-up is easy: crack the door a hair, run the control open until the top of the stove is hot, then back it down to maintain clean, secondaries-on burns. This is a forgiving stove; it doesn’t require micromanagement to avoid smoldering. Feed it dry wood and it rewards you with clear glass and minimal smoke at the cap.

Speaking of glass, the viewing area is larger than you’d expect for the size of the insert, and the airwash works well. I’ve only needed a quick wipe with a damp cloth and ash on occasion after slow burns. The door seals tight, the latch closes with a satisfying cam action, and the overall feel is more robust than many budget inserts.

Build quality and design

Aesthetically, the Model 21 insert leans traditional, which suits a classic hearth. I tested a black door, but the option for pewter or gold accents is a nice touch if you’re coordinating with existing hardware. The finish holds up well to real use—no blistering enamel or uneven paint curing after the break-in fires.

Internally, the baffle and secondary tubes are standard fare for a non-catalytic unit. They’re easy to access for seasonal cleaning, and after a few weeks of regular use, I had no warping or rattling. If a tube ever shifts during shipping or the first couple of hot cycles, it’s a simple reseat—just make sure everything’s properly captured before lighting.

Maintenance and upkeep

As with any wood-burner, the three essentials apply: seasoned fuel, routine ash management, and annual chimney maintenance. The firebox makes ash removal painless with a flat floor that doesn’t trap coals behind a lip. Vacuum the blower intake occasionally to keep dust from building up on the motor housing. I sweep the liner once mid-season and once after; the secondary combustion does its part to keep creosote in check, but nothing replaces a proper brush and inspection.

Because this is a non-catalytic unit, there’s no catalyst to monitor or replace, which simplifies ownership. Plan to inspect gaskets annually; rope seals are cheap and keep performance consistent.

What could be better

• Documentation could be more complete. Mine arrived with minimal operating guidance, and while the basics are intuitive, a clear quick-start and maintenance checklist would help first-time owners.
• Firebox size limits load flexibility. If you’re trying to process standard 18–20 inch splits, expect to re-cut or live with less-than-ideal stacking. The stove is best with shorter, well-seasoned wood.
• It’s an insert-first design. That’s fine—it is an insert—but it also means the blower is part of the experience. If you prefer silent radiant heat only, there are boxier models with larger fireboxes that rely less on forced convection, albeit at the cost of footprint and fitment flexibility.

Warranty and compliance

Buck backs the unit with a 1-year replacement and 5-year limited parts warranty, with manufacturer registration. As always, proper installation and adherence to local codes matter for both safety and warranty validity. If you’re not comfortable with liners, block-off plates, and clearances, budget for a professional installer; it’s money well spent.

Who it’s for

• Homeowners with an existing masonry fireplace who want real heat without the complexity of a catalytic stove.
• Small-to-medium spaces (or medium spaces in milder climates) that benefit from steady, supplemental heat.
• Anyone who values a traditional look, a clean viewing window, and a set-it-and-forget-it blower that spreads warmth efficiently.

If you have a sprawling, compartmentalized home or regularly face sub-zero temperatures, consider stepping up to a larger firebox to reduce reloads. The Model 21 insert can still play a strong supporting role, but expectations should match its size.

Final recommendation

I recommend the Model 21 insert for homeowners seeking a reliable, non-catalytic fireplace upgrade that actually heats. It’s well-built, straightforward to operate, and the heat-activated blower does an excellent job turning radiant warmth into whole-room comfort. The cut-to-size trim kit simplifies tricky surrounds, and the traditional styling blends into most hearths without drama.

Its limitations—modest firebox, sparse documentation—are real but manageable. If your space aligns with its intended coverage and you’re comfortable with a slightly more hands-on burn routine, the Model 21 insert delivers solid performance and everyday usability at a sensible size.