Osburn 3500 Wood Insert


Status: In Stock




Introducing the 3500 Wood Insert, a remarkable solution to enhance your fireplace and elevate your home's heating efficiency. This wood insert is designed to cater to medium to large-sized applications, making it an excellent choice for spaces in the range of 1,000 to 2,700 square feet.

With its impressive overall firebox volume of 3.5 cubic feet, the 3500 Wood Insert offers ample space to accommodate larger logs, allowing for longer burn times and fewer interruptions. This means you can enjoy the warmth and ambiance without constantly tending to the fire.

The 3500 Wood Insert delivers exceptional heating performance with a maximum heat output of 110,000 BTU/h (32.2 kW), ensuring a cozy and comfortable environment. It features an adjustable heat output rate, ranging from 17,200 BTU/h (5.0 kW) to 57,800 BTU/h (16.9 kW), providing you with the flexibility to customize the heat level according to your preferences.

This wood insert boasts remarkable overall efficiency, reaching up to 77% when using dry cordwood, ensuring that you get the most out of every log and minimizing energy waste. It also has a low average particulate emissions rate of just 1.6 g/h, contributing to a cleaner and healthier indoor environment.

If you have a medium to large-sized living space, the 3500 Wood Insert is an ideal choice to efficiently and effectively heat your home while adding a touch of elegance and sophistication to your fireplace.

A Tax Credit is available for this product!

Required Accessories:

Requires the addition of one each of (A), (B) and (C)  required accessories to complete the unit


  • OA10163 Black Door Overlay


  • OA10032 Regular Faceplate(32" X 44")


  • OA10125 Black Faceplate Trims (32" X 44")



  • Fuel type: Dry cordwood
  • Recommended heating area (sq. ft.): 1,000 - 2,700
  • Overall firebox volume: 3.5
  • EPA loading volume (cu. ft.): 2.84
  • Maximum burn time: 10 h
  • Maximum heat output (dry cordwood): 110,000 BTU/h (32.2 kW)
  • Overall heat output rate (min. to max.): 18,200 BTU/h (5.3 kW) to 49,500 BTU/h (14.5 kW)
  • Average overall efficiency (EPA cribs/Douglas fir): N.A. (HHV) N.A. (LHV)
  • Average overall efficiency (dry cordwood): 71% (HHV) 76% (LHV)
  • Optimum efficiency: 77%
  • Average particulate emissions rate: 1.32 g/h
  • Average CO: 92 g/h

Values are as measured per test method, except for the recommended heating area, firebox volume, maximum burn time and maximum heat output.

Recommended heating area and maximum burn time may vary subject to location in home, chimney draft,heat loss factors, climate, fuel type and other variables. The recommended heated area for a given appliance is defined by the manufacturer as its capacity to maintain a minimum acceptable temperature in the designated area in case of a power failure.

The maximum heat output (dry cordwood) is based on a loading density varying between 15 lb/ft³ and 20 lb/ft³. Other performances are based on a fuel load prescribed by the standard. The specified loading density varies between 7 lb/ft³ and 12 lb/ft³. The moisture content is between 19% and 25%.

(Average Overall Efficieny) As measured per CSA B415.1-10 stack loss method.

(HHV) Higher Heating Value of the fuel.

(LHV) Lower Heating Value of the fuel.

Performances based on a fuel load prescribed by the standard at 7 lb/ft³ and with a moisture content between 19% and 25%.

Optimum overall efficiency at a specific burn rate (LHV).

 This appliance is officially tested and certified by an independent agency.



Combustion technology: Non-catalytic
High-efficiency certified appliance: Yes, EPA 2020 approved
Maximum log length: 22"
Log positioning: Over width
Chimney diameter: 6"
Flue outlet diameter: 6"
Type of chimney: Liner - ULC-S635, CAN/ULC-S640, UL1777
Minimum chimney height (feet): 15'
Baffle type: C-Cast
Door type: Single, glass with cast iron frame
Glass type: Ceramic glass
Glass surface – dimensions (Width X Height): 18 7/8" X 11 3/4"
Glass air-wash system: Yes
Premium quality blower included (CFM): 144
Overall dimension (Height): 25 3/4"
Overall dimension (Width): 30 3/8"
Overall dimension (Depth): 29"
Door opening – dimension (Height): 9 7/8"
Door opening - dimension (Width): 19"
Firebox – dimension (Height): 12 7/8"
Firebox – dimension (Width): 22 7/8"
Firebox – dimension (Depth): 20 1/8"
Firebox lined with refractory bricks for better heat distribution: Yes
Stainless-steel secondary-air system improving gas combustion: Yes
Steel thickness – body: 3/16"
Steel thickness – top: 3/8"
USA standard (emissions): EPA
Canadian Standard (emissions): CSA B415.1-10
USA standard (safety): UL 1482, UL 737
Canadian standard (safety): ULC S627
Tested and listed as per applicable standards: By an accredited laboratory (CAN/USA)
Warranty: Limited lifetime

Minimum clearances to combustibles*
(Data expressed in inches. 1 inch = 25.4 mm)


Canada   USA

Clearance – top (measured from the platform on which the appliance is installed)** 84" 84"
Clearance – combustible side mantle to unit 9" 9"
Clearance – combustible top mantle to unit 27" 27"
Clearance – combustible side wall to unit 19" 19"
Clearance – top shelf to unit 27" 27"

* The information given on the certification label affixed to the appliance always overrides the information published in any other media (owner's manual, catalogues, flyers, magazines and/or web sites).

** Some appliances have been tested with a low ceiling. Before setting up your unit, refer to the installation manual.































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































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