Osburn Matrix-I Wood Insert

The Osburn Matrix-I Wood Insert is an EPA 2020 certified wood insert for 500 to 2,100 sq ft. It burns up to 8 hours on a load and takes a 6-inch (insert liner) chimney.

Who it's for

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.

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.

How it performs

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.

Good to know

• 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.
• Same platform as the Destination 2.3 Insert; choose by aesthetic and brand.
• Blower noise is the most consistent owner complaint.

Dimensions

Minimum fireplace opening

Measure the inside of the firebox: width, height and depth. The insert needs at least this much, and the faceplate covers the rest of the old opening.

Dimensions from the specification sheet

Dimensions

Where it can go

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.

Clearances to combustibles

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.

Clearances

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.

Documents

• Osburn Matrix wood insert install & owner's manual (PDF - 5.8 MB)
• Osburn Matrix-I Dimensions (PDF - 0.4 MB)
• Matrix door handle replacement instructions (PDF - 2.8 MB)
• Maximum recommended heating area by climate zone (PDF)
• Osburn wood products brochure, USA edition, with dimension drawings (PDF)
• Osburn limited lifetime warranty
• EPA test reports
• Replacement parts

Details

Warranty

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.

Heat

From the specification sheet

Choices and prices

Options

The unit price is Osburn's 2026 list price for the wood insert alone. Options sold on this page add to it; those marked on request we add to your order by hand.

Faceplate and trim

Fresh air

Other options

What arrives

• 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

Installation

Chimney requirements from the specification sheet

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.

Codes and approvals

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.

Planning the install

• Check with your building department and insurer: wood appliances need a permit in most places and an inspection after installation.
• The chimney is the other half of the system. It is sold separately and quoted from your installer's plan.
• Clearances and floor protection come from the manual and depend on the pipe and shields you choose. Send us your plan and we will check it.
• Burn seasoned wood below 20 percent moisture. Wet wood is the cause of most complaints about any wood stove.
• Special-order goods ship by freight.