Osburn Matrix 2700 Wood Insert

Right buyer

Owners of a working masonry fireplace with a large opening who want to convert an inefficient open hearth into a serious primary heat source — up to 2,200 sq ft of zone heating capability with a 2.5 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 minimum opening dimensions (27 1/8" H × 31 3/4" W × 22 1/8" D per manual) are the basic requirements.

Buyers heating 1,500–2,000 sq ft as primary winter heat in moderate climates, or 1,200–1,500 sq ft in cold climates and older homes. The Matrix 2700 sits in the upper-middle of the Osburn insert line — meaningfully more firebox than the 1700-I, with a different aesthetic and heat-distribution profile from the larger 3500-I.

Buyers prioritizing low emissions. At 1.2 g/hr published average particulate emissions, the Matrix 2700 is class-leading among Osburn wood inserts and well below the EPA 2020 cordwood limit (2.5 g/hr). For EPA non-attainment counties, jurisdictions with stricter local emission rules, or buyers who simply want the cleanest-burning insert available in this size class, this is the right tool.

Buyers who want a contemporary aesthetic and the largest viewing window. The 24 3/8" × 12 5/8" wide-format ceramic glass is the largest in the Osburn insert line, set into a flush-mount cast-iron faceplate that sits cleanly inside the existing masonry opening rather than projecting forward. Wide picture-frame proportions, configurable cast-iron door overlay in Black or Brushed Nickel.

Buyers who want the most powerful blower in the Osburn insert lineup. The 176 CFM heat-activated double-cage blower meaningfully outperforms the 144 CFM blowers used in the smaller and larger Osburn inserts. For an insert — where most of the firebox sits inside the masonry cavity — blower CFM is what gets the heat into the room.

Wrong buyer

Not for buyers without an existing code-compliant masonry fireplace with a large opening. Wood inserts must be installed inside a lined masonry fireplace with a continuous stainless-steel chimney liner running the full height. This insert requires a substantial opening (27 1/8" H × 31 3/4" W × 22 1/8" D per manual) — many older or smaller fireplaces will not accept it. Not approved for factory-built (prefab) metal fireplaces, mobile homes, alcoves, or freestanding installation.

Not for buyers heating under 1,200 sq ft. The 2.5 ft³ firebox will overheat a smaller space and force you to run it inefficiently. For smaller spaces, step down to the Osburn 1700-I.

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, consider a catalytic insert in this size class.

The Matrix 2700 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. The 22 1/8" minimum depth is meaningfully deeper than smaller Osburn inserts and is the most common reason this insert does not fit a shallower hearth.

Projection kit (optional)

If the fireplace depth is less than the minimum 22 1/8", the optional projection kit (SBI AC01263) extends the insert 2 or 4 inches forward of the fireplace facing. With the kit installed, the depth requirement reduces to 20 1/8" (2" projection) or 18 1/8" (4" projection). Ordered as a separate accessory.

Faceplate options

The standard cast-iron faceplate covers most masonry openings. For larger openings, the optional 18-gauge cuttable faceplate extends the cover area — the edges can be trimmed to contour an arched fireplace or to minimize visible flashing. The door overlay (Black or Brushed Nickel) is configured at order — one overlay is required to complete the unit.

Clearances to combustibles

The certification label on the back of the insert always overrides clearance figures published elsewhere. Reduced clearances are not available by means of heat shields on this insert — the figures above are the binding minimums.

Floor protection

Floor protection requirements depend on whether the projection kit is installed and whether the existing masonry hearth is raised above the surrounding combustible floor. Without the projection kit, the manual requires a non-combustible floor protector extending at least 18 inches in front of the unit in Canada or 16 inches in the USA, measured from the door opening. If the masonry hearth is level with or only slightly raised above the surrounding combustible floor, an R-value floor protector may be required per the manual's floor-protection worksheet. With the projection kit installed, the forward extension threshold increases. The manual includes a thermal-resistance lookup table for common floor protection materials (brick, cement board, ceramic tile, marble) to calculate the required R-value combination. Tile alone is not sufficient — the manual requires a continuous non-combustible sheet beneath any tile installation. Final hearth protection must be calculated from the manual's floor-protection worksheet and approved by the installer/AHJ.

Chimney and liner

The Matrix 2700 requires a continuous 6-inch stainless-steel chimney liner extending from the insert flue collar to the top of the chimney. The liner must conform to ULC S635, CAN/ULC-S640 (Canada) or UL 1777 (USA) and be rated for solid fuel. The minimum liner height is 15 feet, subject to installer verification, certification label, draft conditions, and local code. 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.

The Matrix 2700 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.

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. A sheet-metal block-off plate sealed at the damper level (or, in Canada per CSA B365, mineral wool packing around the liner) is recommended at the throat 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.

Outside air

An optional fresh-air intake kit is available for code jurisdictions requiring outside combustion air or for tight new-construction homes with mechanical ventilation. In conventional homes the manual identifies room air as the safest and most reliable supply for combustion; almost all houses have enough natural leakage to provide what the insert needs. A smoke detector and carbon monoxide detector 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. 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

• Osburn Matrix 2700 wood insert (OB02700) with welded carbon-steel firebox and cast-iron glazed door
• Standard cast-iron faceplate (30 1/8" × 43 5/8")
• Configured at order with required door overlay selection — see "Where it can go" for the options
• 176 CFM heat-activated double-cage blower assembly with rheostat speed control and three-position switch (AUTO / OFF / MANUAL)
• C-Cast baffle and stainless-steel secondary-air tube assembly
• Moulded refractory bricks lining (floor, sides, back)
• Adjustable threaded legs
• Removable air-control handle
• Liner fixation brackets and hardware
• Owner's 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, extending at least 16 inches in front of the unit in the USA, 18 inches in Canada
• Sheet-metal block-off plate, high-temp silicone, and mineral wool insulation — effectively required in practice for the insert to deliver rated performance
• Optional projection kit, 2" or 4" (SBI AC01263) — for installations where the fireplace depth is less than the 22 1/8" minimum
• Optional 34" × 50" cuttable faceplate, 18 GA (SBI AC01277) — for masonry openings larger than the standard faceplate covers
• Optional 5-inch fresh-air intake kit (SBI AC01298) — for code jurisdictions requiring outside combustion air or for tight new-construction homes
• Optional 5-inch × 4' insulated flex pipe for fresh-air intake (SBI AC02090) — HVAC type, ULC S110 or UL 181 class 0 or class 1
• Optional firescreen door (SBI AC01275) — 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
• Optional liner hook-up system (SBI AC02006) — simplifies liner-to-flue-collar connection
• Optional offset liner adapter (SBI AC01214) — for installations where the chimney throat geometry requires offset connection
• Optional tempered glass hearth pad 10mm 18" × 50" (SBI AC02760)
• 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 80,000 BTU/hr maximum is a peak rating, transient, achieved on dry cordwood at high loading density and short reload intervals. It is real, but it is a peak rating, not the average output across a full burn cycle of normal operation. The figure that matters for daily life is the sustained output across a full burn cycle, which lands in the 12,700–60,700 BTU/hr band per the CSA B415.1-10 stack-loss method — a wide range covering shoulder-season heating on the low end and serious cold-snap output on the high end.

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 176 CFM heat-activated double-cage 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. The 176 CFM rating is the strongest in the Osburn insert line — meaningful for an insert in this size class. The rheostat lets you dial speed down for quieter operation once the room is up to temperature.

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. Allow the insert to reach operating temperature (approximately one hour from a cold start) before turning the blower to MANUAL. Per the manual, turning the blower on too early during start-up pulls heat away from the firebox and slows the build-up to clean combustion.

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. The wide-format glass — largest in the Osburn insert line — makes glass cleanliness more visually important than on smaller inserts.

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.

Large appliance, large masonry opening required. The 2700's minimum opening of 27 1/8" H × 31 3/4" W × 22 1/8" D is substantial. Many older or smaller fireplaces will not accept it — particularly the 22 1/8" depth requirement, which is deeper than most other inserts in the Osburn line. Measure carefully before ordering — this is the most common reason a Matrix 2700 purchase falls apart at the installation stage.

Efficiency is lower than smaller siblings. 64% HHV is lower than the 68% HHV on the Osburn 1700-I and 71% HHV on the 3500-I. The Matrix 2700's standout numbers are the class-leading published emissions rate and the 80,000 BTU/hr output, not efficiency. Buyers comparing efficiency numbers across the line should know this going in — it's a real trade-off.

Low published emissions is the headline. If emissions matter for your jurisdiction (EPA non-attainment counties, stricter local rules, future regulatory changes), the Matrix 2700's 1.2 g/hr published average particulate emissions are class-leading among Osburn wood inserts. For many buyers this is the single best reason to pick the 2700 over the 3500-I.

Powerful blower, audible blower. The 176 CFM blower delivers strong heat distribution but is more audible than the smaller blowers on other inserts in the line. The rheostat lets you dial speed down for quieter operation when the room is up to temperature; high speed is most useful during the active heat-output phase of the burn cycle. Multiple owner reports describe the blower as noticeably loud at higher settings.

Blower auto-activation can be finicky. A meaningful number of owner reports cite blower thermodisc activation issues — the blower failing to engage in AUTO when the insert reaches operating temperature, or running constantly regardless of switch position. The issue is usually improper thermodisc seating against the insert body during installation; have the installer verify the sensor mounting before sign-off and test all three switch positions (AUTO / OFF / MANUAL) before the installer leaves.

8-hour maximum burn is large-class, not long-burn class. A 2.5 ft³ non-cat insert gives you meaningful primary-heat capability across 1,500–2,000 sq ft, with realistic 6–7 hour burn cycles. If you want true 10+ hour overnight burns, consider a catalytic insert in this size class with a real low-output mode.

The 2,200 sq ft figure is aspirational. The most consistent owner regret across large inserts is buying for the high end of the manufacturer's heating range. If you need to reliably heat more than ~2,000 sq ft as primary winter heat in a cold climate or older home, this insert is at its limit — supplemental heat in the coldest part of winter may still be needed.

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.

535 lb shipping weight is heavy. Plan for three-person handling minimum and verify the installation route — stairs, narrow doorways, and tight masonry access make the install meaningfully harder than for smaller inserts. Several owner reports cite installation difficulty as the single hardest part of owning this insert.

Liner, block-off plate, and labor are not in the appliance price. The insert is the appliance; the chimney liner, the block-off plate, the insulation wrap, and the professional installation are separate purchases that need to be planned for. Older or taller chimneys, offset flues, and damper-frame removal add to install complexity. Skipping the liner, the block-off plate, or the insulation wrap saves money up front and costs measurable performance and creosote durability after.

Large window makes glass cleaning visible. The wide-format 24 3/8" × 12 5/8" ceramic glass is the largest in the Osburn insert line, which is a major selling point but also means low-burn glass tarring is more visually noticeable. Daily wipe during low-burn weather; weekly during high-burn.

East-west loading only. The 12 7/8" firebox depth is too shallow for north-south log loading. All loading is across the width of the firebox, sides visible from the door. Less flexibility than the deeper-firebox Osburn 3500-I.

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.

Configuration is a one-time decision. Door overlay color (Black or Brushed Nickel) is configured at order, not field-swappable. Choose the configuration that matches the fireplace you're installing into.

First burns. The first three to six fires release paint VOCs as the high-temperature stove paint cures. The smell can be strong; ventilate the room well and avoid prolonged exposure during cure-in. Run the insert hot and expect the smell to disappear permanently after the cure-in.

Lighting. Per the manual, the recommended method is the EPA loading procedure for cleanest combustion: place two small pieces (about 3" × 3") in the bottom in a reverse-V shape, two medium-size pieces (about 4" × 4") in an east-west orientation in the back over the reverse V, and a big piece (about 5" × 5") in the front over the reverse V. Leave air space between pieces. Light, leave the door open for three minutes or until the fire is fully established, then close with the air control fully open. The manual also describes alternative methods (conventional bottom-up, top-down, two-parallel-logs).

Air control. Single-lever, located below the ash shelf. Push the handle to one position for HIGH (full air) and the opposite position for LOW (minimal air). Full open at light-off; gradually closed only after the load is fully engaged and stable secondary flames are established. Closing too fast and the fire smolders. Do not elevate the fire by using a grate.

Blower switch positions. The 176 CFM blower assembly has a three-position switch: (1) AUTO — blower starts when the insert is hot enough and stops when it cools down (thermodisc-controlled); (2) OFF — blower stopped, prevented from starting automatically; (3) MANUAL — runs continuously regardless of insert temperature. Use AUTO for normal operation; use MANUAL only when you want continuous airflow regardless of temperature. Allow the insert to reach operating temperature (approximately one hour from cold start) before turning the blower to MANUAL.

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. Place the new load on and at the back of the embers. Open the air for a minute or two before opening the door, open the door slowly to avoid smoke rollout, load, close the door, and run the air open until the load is fully engaged before reducing gradually. Turn the blower OFF before opening the door fully to reduce ash disturbance.

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.

Carbon monoxide watch. Per the manual, if the firebox no longer shows flame but still contains unburned logs, check outside for smoke from the chimney. Smoke without flame means the fire is air-starved and CO levels are rising. Open the door slightly, move the logs with a poker, create a passage for air by making a trench in the ember bed, and add small kindling-size pieces to restart combustion.

Ash management. The Matrix 2700 uses a hollow-bottom firebox; ash is scooped manually from the front. 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 and releases carbon monoxide. 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. Daily wipe during low-burn weather; weekly during high-burn. Black streaks at the lower edge mean wet wood; black uniformly across the glass means burns are running too cool. Brown stains at the lower corners mean smoky combustion. 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 — remove the split pin with pliers and turn the handle one counterclockwise turn to increase pressure. Plan on every 3–5 seasons in regular use.

Annual chimney sweep. Per the manual, the chimney and 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; monthly is safer for new burners. If buildup reaches 1/8 inch, sweep immediately. The baffle and secondary tubes lift 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 manual specifically calls for lubrication. If the blower fails to engage automatically when the insert reaches operating temperature in AUTO, have the installer or dealer inspect the thermodisc mounting and contact with the insert body — improper seating is the most common cause of auto-activation issues on this insert. Replacement blowers and related service parts are available through Osburn/SBI dealers and parts channels if needed years out.

Refractory bricks and baffle. The intense heat of the fire can cause slight cracks in the refractory bricks — minor cracks do not reduce effectiveness. Inspect periodically and replace any wider cracks. The baffle and secondary tubes can be removed for sweep access and inspection. Operation with a cracked or missing baffle may cause unsafe temperatures and voids the warranty.

Chimney fire response. If a chimney fire occurs: close the insert door and the air-intake control, alert occupants, contact the fire department if assistance is needed, use a dry chemical fire extinguisher or baking soda or sand to control the fire (never water — it causes a dangerous steam explosion), and do not use the appliance again until the insert and chimney have been inspected by a qualified chimney sweep or fire-department inspector.

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 compressed logs made of wax-impregnated sawdust or logs with chemical additives; 100% compressed-sawdust logs can be used with caution.

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. SBI's parts network is well-stocked — replacement bricks, baffle, secondary tubes, glass, gaskets, and blower are openly available at fair prices through multiple parts vendors.

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.