Osburn Matrix-I Wood Insert

Right buyer

Owners of a working masonry fireplace who want to convert an inefficient open hearth into a serious heat source — up to 2,100 sq ft of zone heating capability with a 2.4 ft³ firebox, 20-inch log capacity, and an 8-hour maximum burn cycle. Reasonable insulation, access to seasoned hardwood at 15–20% moisture, and an existing masonry fireplace that meets the manual's minimum opening dimensions (23 3/8" H × 28 7/8" W × 19 5/8" D) are the basic requirements.

Buyers who want the Osburn brand finish with a contemporary aesthetic. The Matrix surround is a clean cast-iron flush-mount face designed to sit nearly flush with the masonry — a modern look that uses one of the largest near-square glass viewing areas in the medium-large insert class (19 5/8" × 11 7/8") as the visual focus rather than ornate decorative castings. The standard 36 1/8" × 25 1/8" cast-iron surround is included; optional backing plate kits extend the cover area for larger or older masonry openings.

Buyers who want a single appliance to do the work of zone heating across a main living area. The 14,200–44,500 BTU/hr tested output band gives meaningful flexibility — from mild-weather low-output operation up to serious cold-weather heat. With the heat-activated 90 CFM blower, warm air circulates from the firebox jacket out into the room automatically once the insert is up to temperature.

Buyers who value Canadian-built SBI quality and the lifetime warranty on the combustion-chamber welds and cast-iron door frame. The Matrix shares the same medium-large SBI insert platform as the Enerzone Destination 2.3 Insert — proven chassis, EPA 2020 cordwood certified, broadly available parts and dealer support across North America.

Wrong buyer

Not for buyers without an existing code-compliant masonry fireplace. Wood inserts must be installed inside a lined masonry fireplace with a continuous stainless-steel chimney liner running the full height. This insert is not approved for factory-built (prefab) metal fireplaces, mobile homes, or any installation outside a masonry hearth.

Not for buyers expecting 10+ hour overnight burns. The 8-hour manufacturer maximum is achievable on a packed load of dense hardwood with the air shut down hard, but useful heat from a packed load is realistically 6–7 hours. For longer burns, step up to a 3.0+ ft³ insert or to a catalytic insert with a real low-output mode.

Not for buyers wanting traditional decorative cast-iron styling. The Matrix surround is intentionally clean and modern. Buyers wanting heavy traditional castings, louvered faceplates, or ornate visible-grille styling should look at the Enerzone Solution 2.3-I (traditional faceplate option) or premium-tier alternatives.

Not for buyers sensitive to blower noise. The 90 CFM blower is single-speed (no rheostat or variable-speed control) with a thermodisc heat sensor for AUTO operation. Owner reviews consistently flag the blower as louder than expected for this class of insert. AUTO mode reduces run time but does not change the volume when it's running.

The Matrix Insert is approved only for installation inside an existing code-compliant masonry fireplace with a continuous stainless-steel chimney liner. It is not approved for installation in factory-built (prefab) metal fireplaces, in mobile or manufactured homes, in alcoves, or as a freestanding unit. The masonry fireplace and chimney must be inspected before installation for cracks, loose mortar, creosote, blockage, or other signs of deterioration.

Minimum masonry opening

If a fresh-air intake is being installed, add at least 4 inches to the width. Plan for a small installation margin above the insert to seat the liner adapter — an opening exactly at the minimum will be a tight install. Measure carefully before ordering.

Projection kit (optional)

If the fireplace depth is less than the minimum 19 5/8", the optional projection kit (SBI AC01323) extends the insert 2 or 4 inches forward of the fireplace facing. With the kit installed, the depth requirement reduces to 17 5/8" (2" projection) or 15 5/8" (4" projection). The projection kit requires one of the optional faceplate backing plate kits to secure to it. Ordered as a separate accessory.

Faceplate options

The standard four-piece cast-iron flush-mount surround ships with the insert and covers most modern masonry openings. For larger or older openings, choose the backing plate kit (29" × 44" or 29" × 50") that matches the masonry opening — installs to the back of the standard surround to extend the cover area. Backing plate kits are ordered as separate accessories.

Clearances to combustibles

A combustible mantel shelf with a maximum depth of 12 inches may be installed at a height of at least 27 inches above the insert. At greater heights the shelf must still observe the 12-inch maximum depth. The certification label affixed to the insert (located underneath, behind the blower) always overrides clearance figures published in any other media.

Floor protection

Floor protection requirements depend on whether the existing masonry hearth is raised 5 inches or more above the surrounding combustible floor. If the hearth is raised 5 inches or more, a non-combustible floor protector with no R-value is required and must extend at least 16 inches in front of the unit in the USA, 18 inches in Canada. If the hearth is raised less than 5 inches, a non-combustible floor protector with an R-value of at least 1.00 is required and must extend at least 23 inches in front of the unit. The manual includes a thermal-resistance lookup table for common floor protection materials (brick, cement board, ceramic tile, marble, etc.) to calculate the required R-value combination.

Chimney and liner

The Matrix Insert performs best with a 6-inch stainless-steel chimney liner. In the USA, use a 6-inch liner listed to UL 1777. In Canada only, connection to a chimney liner of at least 5 inches may be permitted if it properly vents combustion gases, the total masonry chimney height is greater than 20 feet, and the application is verified and authorized by a qualified installer. The insert is not approved for a positive flue connection to clay tile — a continuous stainless liner is required.

The minimum chimney height is 12 feet, subject to installer verification, certification label, draft conditions, and local code. The manual also states that the total system height (from the floor the appliance sits on to the top of the chimney) should never be less than 15 feet for reliable draft. The chimney must extend at least 3 feet above the highest point of contact with the roof and at least 2 feet above any roof line or obstacle within 10 feet horizontally.

If the existing fireplace's throat damper is to remain, it must be locked open to clear the liner; otherwise the damper plate must be removed and a notice plate (#27009, supplied with the owner's manual kit) must be installed inside the masonry hearth in a visible place. A sheet-metal block-off plate sealed at the damper level (or, in Canada per CSA B365, mineral wool packing around the liner) is effectively required in practice to reduce cold-air backdraft and to allow the insert to deliver rated performance — without it, jacket-recovered heat is lost into the smoke chamber. An insulated liner (or pre-insulated liner with a wrap) improves draft and reduces creosote, and is required by code in some jurisdictions for clearance reasons.

The manual strongly recommends an interior chimney rising straight up through the tallest part of the house. Outside chimneys lead to cold backdrafting when there is no fire, slow kindling of new fires, and smoke roll-out when the door is opened for loading.

Outside air

The manual identifies room air as the safest and most reliable supply of combustion air for this insert — almost all houses have enough natural leakage to provide what the insert needs. An optional 5-inch fresh-air intake kit is available for tight new-construction homes, for code jurisdictions requiring outside combustion air, or where powerful kitchen-range exhausts create negative pressure in the home. A smoke detector, a carbon monoxide detector, and a fire extinguisher are required in the room where the insert is installed.

Code compliance

Code compliance for any specific installation is determined by the local Authority Having Jurisdiction. Manufacturer listings cover what the insert is approved for; the AHJ approves what is permitted at your address. A WETT (Canada), NFI, or CSIA (USA) certified installer is strongly recommended and frequently required by code, permit, or insurance — and required for warranty coverage. In Canada the CSA B365 standard applies; in the USA, ANSI NFPA 211 applies. Confirm local requirements before purchasing, particularly in EPA non-attainment counties and in HOA jurisdictions where new wood-burning installs may be restricted.

California Proposition 65

This product can expose you to chemicals including carbon monoxide, which is known to the State of California to cause cancer, birth defects or other reproductive harm. For more information go to www.P65warnings.ca.gov.

Ships with the insert

• Matrix wood insert (OB02028) with welded carbon-steel firebox and cast-iron door frame with ceramic glass
• Four-piece cast-iron flush-mount surround at 36 1/8" × 25 1/8" (top, left, right, and bottom pieces)
• Heat-activated 90 CFM single-speed tangential blower assembly with AUTO/MANUAL/OFF switch, mounted at the bottom of the insert
• C-Cast baffle and four stainless-steel secondary-air tubes
• High-density refractory firebrick lining
• Insert leveling bracket system (2 brackets) for rear-of-unit leveling in the masonry hearth
• Three liner fixation brackets and screws for connecting the stainless-steel liner to the flue collar
• Damper-removal notice plate (#27009) for installations where the masonry throat damper is removed
• Owner's installation and operation manual and product documentation

Sold separately

• 6-inch continuous stainless-steel chimney liner kit (UL 1777, CAN/ULC-S635, or CAN/ULC-S640) — required for installation, sized to the chimney height
• Hearth extension or floor protector sized per manual specifications, with R-value of at least 1.00 if hearth is raised less than 5 inches
• Optional faceplate backing plate kit (SBI AC01322 for 29" × 44" or AC01332 for 29" × 50") — for masonry openings larger than the standard 36 1/8" × 25 1/8" surround
• Optional 2" or 4" projection kit (SBI AC01323) — extends the insert forward of the fireplace facing when fireplace depth is insufficient; requires a faceplate backing plate kit (AC01322 or AC01332) to secure to
• Optional 5-inch fresh-air intake kit (SBI AC01298) — for tight new-construction homes or code jurisdictions requiring outside combustion air
• Optional rigid fire screen (SBI AC01315) — for occasional attended fire viewing only where permitted by local code and only when used exactly as instructed in the fire screen manual; never leave the insert unattended when used with a fire screen. Open-door operation with a fire screen is prohibited in the United States and in Canadian provinces with particulate emission limits
• Pin-type wood moisture meter — not optional in practice
• Flue thermometer — strongly recommended for insert installations since stove-top temperature isn't accessible
• Installation by an authorized qualified technician (WETT, NFI, or CSIA certified) — required for warranty coverage and often required by code, permit, or insurance

The 75,000 BTU/hr maximum is a peak rating, transient, achieved on dry cordwood at high loading density and short reload intervals. The figure that matters for daily life is the sustained output across a full burn cycle, which lands in the 14,200–44,500 BTU/hr band per the CSA B415.1-10 stack-loss method. That's the same operating range as the Destination 2.3 sibling on the same SBI platform — they're tuned essentially identically for combustion and output.

A realistic burn cycle from a packed load of well-seasoned hardwood produces a 30–45 minute warm-up, 2–3 hours of strong sustained heat once the firebox and surrounding masonry come up to temperature, then a gradual decline over the next 3–4 hours with a coal bed remaining. Total useful heat from one full pack is realistically 6–7 hours, occasionally approaching the 8-hour manufacturer maximum with dense hardwood, mild weather, and a packed coal bed.

The masonry around the insert acts as a thermal mass. Once the surrounding brick or stone is up to temperature, it continues radiating heat into the room well after the active fire has died down. This is one of the underappreciated benefits of an insert versus a freestanding stove — the masonry stores and releases heat on its own cycle. The first hour from a cold start is the slowest because that mass has to come up to temperature; once it's hot, response time is faster.

The 90 CFM heat-activated blower is what gets the heat into the room. Because most of the insert's firebox sits inside the masonry cavity, the radiant heat that would otherwise reach the room from a freestanding stove is partly absorbed by the surrounding brick. The convection jacket around the firebox captures that heat and the blower pushes it out into the room. With the switch in AUTO, the blower starts automatically once the insert is hot enough and stops when it cools — set the position and forget about it. With the switch in MANUAL, the blower runs continuously regardless of insert temperature.

Per the manual, the blower can provide up to a 2% efficiency gain when used regularly, but it is not a way to gain more output from an undersized insert. Allow the insert to reach operating temperature (approximately one hour from a cold start) before turning the blower to MANUAL — increased airflow during start-up pulls heat away from the firebox and slows the build-up to clean combustion. AUTO mode handles this timing automatically.

Air-wash glass stays largely clear during proper hot burns at moderate-to-high air settings. At low burn rates with marginally seasoned wood, the glass will tar. This is universal to non-catalytic inserts, not specific to Osburn.

Power-failure operation: the insert continues to burn safely without electricity — only the blower stops. Heat distribution drops noticeably without the blower because the masonry cavity absorbs most of the firebox radiation. Plan accordingly if you're buying this insert specifically as a power-outage heat source.

Insert, not a freestanding stove. The Matrix Insert requires an existing masonry fireplace plus a full stainless-steel chimney liner — there's no other approved installation path. Buyers without a masonry fireplace should look at the Osburn 2000 or Osburn Matrix freestanding stove instead.

Same platform as the Destination 2.3 Insert; choose by aesthetic and brand. The Matrix Insert and the Enerzone Destination 2.3 Insert share the same SBI medium-large insert chassis — same 2.4 ft³ firebox, same 1.95 ft³ EPA loading volume, same combustion chamber dimensions, same 20-inch log capacity, same 75,000 BTU/hr maximum, same 14,200–44,500 BTU/hr tested range, same 2.3 g/hr emissions, same 72% HHV / 77% LHV efficiency, same 90 CFM blower, same 8-hour maximum burn, same warranty schedule. The Matrix is the Osburn-branded version with a contemporary cast-iron flush-mount surround; the Destination 2.3 is the Enerzone-branded version at a different price point with different faceplate styling options. Choose between them by aesthetic preference, dealer relationship, and price — the underlying appliance is the same.

Blower noise is the most consistent owner complaint. The 90 CFM tangential blower is single-speed with a thermodisc heat sensor for AUTO operation — there is no variable-speed control or rheostat. Owner reviews on the manufacturer's site consistently flag the blower as louder than expected for an appliance in this price range. AUTO mode reduces total run time but does not change the volume when it's running. If quiet operation matters more than maximum heat transfer, the Enerzone Solution 2.3-I (different blower system) or a higher-tier insert with variable-speed blower may be a better fit.

Door handle has a known issue. Owner reports include the door handle ball-bearing screw working loose over time, and SBI publishes a model-specific door handle replacement instruction sheet (separate document 46372AF). Not a deal-breaker — the replacement is straightforward and the part is available through SBI dealers — but worth knowing before purchase. Periodic inspection of the door handle hardware is a reasonable maintenance habit.

Medium-large firebox, medium-long burn time. A 2.4 ft³ non-cat insert gives you meaningful primary-heat capability across 1,200–1,800 sq ft, with realistic 6–7 hour burn cycles. If you want true 10+ hour overnight burns, step up to a 3.0+ ft³ insert (like the Pacific Energy Summit Insert LE) or to a catalytic insert with a real low-output mode.

The 2,100 sq ft figure is aspirational. The most consistent owner regret across medium-large inserts is buying for the high end of the manufacturer's heating range. If you need to reliably heat more than ~1,800 sq ft as primary winter heat in a cold climate or older home, step up a firebox size.

The blower is essential, not optional. Unlike a freestanding stove where the blower meaningfully improves heat distribution, on an insert the blower is what gets the heat into the room at all. Most of the firebox sits inside the masonry cavity, which absorbs radiant heat. The insert will run safely without the blower (useful in a power outage), but day-to-day heat into the room depends on the blower being on and working.

Existing fireplace dimensions are non-negotiable. The masonry opening must meet the manual's minimum dimensions (23 3/8" H × 28 7/8" W × 19 5/8" D). Backing plates can cover a larger opening but cannot compensate for an undersized one. The projection kit can extend the insert forward by 2 or 4 inches if depth is short — and requires a faceplate backing plate kit to secure to — but not enough to fit a substantially shallow fireplace. Measure before purchase.

Wood quality is not negotiable. The most common "the insert doesn't heat" complaint comes from owners running marginally seasoned wood. Secondary combustion works best with dry, properly seasoned fuel, ideally around 15–20% moisture. A pin-type moisture meter is the single best accessory for this insert.

Contemporary, not traditional. The cast-iron flush-mount surround is intentionally clean and modern. Buyers wanting heavy decorative cast iron, louvered faceplates, or visible-grille traditional styling should look at the Enerzone Solution 2.3-I (traditional faceplate option) or premium-tier alternatives.

First burns. The first few fires cure the high-temperature paint and condition the internal components. Burn two or three small fires first, then build bigger, hotter fires until the paint smell is gone. The smell can be strong; ventilate the room well and avoid prolonged exposure during cure-in. Fresh paint fumes can also trigger false alarms in smoke detectors.

Lighting. The manual describes the top-down method as the preferred ignition technique: small kindling on top, medium pieces below, light from the top so the fire burns downward. Place two small pieces on each side of the firebox, crumple 5–10 sheets of newspaper between them, cross the remaining small pieces over the newspaper, then place five larger pieces on top crossing them in two layers. Open the air control fully, light the paper, leave the door slightly ajar for about 5 minutes, then close the door with the air still fully open. Close gradually only when the firebox is full of bright turbulent flames and the wood edges are glowing.

Air control. Single lever located underneath the ash shelf. Push the handle completely to the left for high (open), completely to the right for low (closed). Full open at light-off; gradually closed only after the load is fully engaged and stable secondary flames are established. The manual specifies closing the primary air control gradually — too fast and the fire smolders. If flames diminish to the point of disappearing, the air was closed too early or the wood is too wet. This wood heater has a manufacturer-set minimum low burn rate that must not be altered — it is against federal regulations to alter this setting.

Blower switch positions. The 90 CFM blower assembly has a three-position switch: AUTO (position 1, heat-sensor-controlled, starts when insert is hot and stops when cool), OFF (position 2, prevents the blower from starting automatically), and MANUAL (position 3, runs continuously). Use AUTO for normal operation. Allow the insert to reach operating temperature before turning the blower to MANUAL from a cold start.

Reload cadence. 3–4 hours between reloads in active heating use; up to 7 hours for a final overnight pack with the air shut hard. Rake remaining charcoal toward the front of the firebox before loading — this concentrates the coals near where most of the combustion air enters and helps ignite the new load. Open the air for a minute or two before opening the door, open the door slowly to avoid smoke rollout, load with the new pieces toward the rear on top of the embers, close the door, and run the air open until the load is fully engaged before reducing gradually. Do not elevate the fire by using a grate or andirons.

Burn in cycles, not single-log feeds. The manual is explicit: do not attempt to produce steady heat output by placing a single log on the fire at regular intervals. Always place at least three (preferably more) pieces on the fire at a time so the heat radiated from one piece helps ignite the pieces next to it. Each load should provide several hours of heating.

Ash management. Empty ash every 2–3 days during full-time heating. The best time to remove ash is in the morning after an overnight fire when the insert is relatively cool but there is still some chimney draft to draw ash dust into the insert rather than into the room. Always dispose of ash in a tightly covered metal container on a non-combustible surface, well away from combustible materials — ash retains hot embers for days. Never store ashes indoors, in a non-metallic container, or on a wooden deck.

Glass cleaning. Damp newspaper dipped in cold ash, or a dedicated ceramic-glass cleaner. A whitish dusty deposit forms on the inner glass during normal operation and wipes off easily when the insert is cold. Light brown stains in the lower corners mean smoky combustion at low burn rates — usually wet wood or air closed too early. Brown streaks from the edge of the glass means the glass gasket needs replacement. Do not clean the glass when the insert is hot, and do not strike or slam the glass door shut.

Door and glass gaskets. Per the manual, the door gasket needs replacement when the paper-strip test fails: close the door on a strip of paper and try to pull it out; firm resistance means the gasket is sealing, easy pull means it's time to replace. Test all the way around the door. The latch mechanism is adjustable via the top and bottom bolts (depth and gasket tension) and the left and right bolts (handle angle) on the door pressure plate. Glass gasket is flat, adhesive-backed, woven fibreglass — must be centered on the edge of the glass during replacement and not stretched. Plan on every 3–5 seasons in regular use.

Annual chimney sweep. Per the manual, the chimney liner should be cleaned and inspected at least once each year. Inspect every two months during the heating season until you know your creosote-formation rate; weekly cleaning may be necessary in mild-weather low-burn conditions. If buildup reaches 1/8 inch, sweep immediately. The baffle lifts out for sweep access. Insert installations make sweeping more involved than freestanding stoves — many owners hire a CSIA-certified sweep rather than doing it themselves.

Wood seasoning. Hardwood needs 12–24 months split, stacked off the ground, top-covered, with sun and wind on the sides. Don't trust supplier "seasoned" claims — use a pin-type moisture meter, split a piece in half, measure the fresh face. Manual target: 15–20% moisture. Wood above 25% will smolder, soot the glass, line the chimney with creosote, and undercut every published efficiency and emissions number on this page.

Blower maintenance. Keep the blower intake and fins free of dust. Vacuum dust accumulation annually. Do not oil the blower unless the blower manual specifically calls for lubrication. Owner reports note that bearings can develop a squeak after a season or two; pulling, cleaning, and adjusting the bearings typically resolves it. Replacement blowers and related service parts are available through Osburn/SBI dealers and parts channels if needed years out.

Door handle inspection. Periodically check the door handle hardware for looseness. SBI publishes a separate door handle replacement instruction sheet (document 46372AF) — keep the model and serial numbers handy when ordering replacement parts. The handle assembly is a normal wear item across the SBI medium-large insert platform.

What never to burn. Per the manual and EPA fuel rules: no coal, garbage, yard waste, materials containing rubber or plastic, waste petroleum products, paint or paint thinners, asphalt products, painted or pressure-treated wood, railroad ties, manure or animal remains, plywood, particle board, paper products, asbestos materials, construction or demolition debris, salt-water driftwood, or unseasoned wood. This does not prohibit normal fire starters made from paper, cardboard, sawdust, wax, or similar substances when used only to start a fire. Burning prohibited materials destroys the firebox, voids the warranty, and releases toxic compounds into your home and the chimney. Do not burn manufactured logs made of wax-impregnated sawdust or logs with chemical additives; 100% compressed-sawdust logs can be used with caution but never more than the manufacturer-recommended quantity.

The Osburn limited lifetime warranty applies to the original retail purchaser only and is non-transferable. The warranty applies to normal residential use only. Proof of purchase (dated bill of sale), model name, and serial number are required for any warranty claim. Online registration is recommended at osburn-mfg.com but not required if a dated invoice is retained.

Coverage by component

A one-time replacement limit applies to all parts with lifetime coverage. Warranty is void if the unit is used to burn anything other than seasoned cordwood, or if it is not operated according to the owner's manual. Damage caused by misuse, improper installation, lack of maintenance, overfiring, downdrafts, venting problems, or under-estimated heating area is not covered. Improper installation by anyone other than an authorized qualified technician voids the warranty.

Warranty claims are made through your Osburn dealer and remain subject to SBI/Osburn inspection, approval, and the current written warranty. Kaminos is the retailer for this insert and supports buyers through purchase; final warranty approval rests with SBI as the manufacturer.

Osburn may require photos or returned parts to support a claim; repair work covered by warranty requires prior manufacturer approval.

Coverage details can change by component and warranty revision; the current Osburn warranty controls.