FRFP
Item #: OB03500
SKU: OB03500
Starting at:
$3,599.00
The 3500 is the heater of the range. Its 3.5 cubic foot firebox is roughly 45% larger than the Inspire 2000 or the Matrix, which means longer burns, fewer reloads, and enough output to carry a house rather than warm a room. If you are heating seriously with wood — through a winter, or through an outage — firebox volume is the specification that decides it.
The included blower matters more on a stove this size than it sounds. A large firebox radiates heat close to the appliance; a blower moves it out into the room and down a hallway. Without one, big stoves tend to cook the space they stand in and leave the rest of the house cold.
At 1.6 g/h of particulate the 3500 burns cleaner than either of the smaller Osburn stoves, which run at 2.3. That is unusual — bigger fireboxes are typically dirtier — and it means less creosote in your flue despite burning far more wood. Non-catalytic, so there is no combustor to replace every few seasons.
Worth knowing before you plan the install: the 3500 vents on a 6" flue, same as the smaller stoves, so it does not demand oversized pipe. But it does need 15 ft of chimney height against 12 ft for the Inspire and Matrix. A big firebox needs draft to run properly, and a short stack will make it sluggish and smoky no matter how good the stove is.
Chimney must be Class A to CAN/ULC S629 or UL 103 HT (2100 °F). If you have a shorter chimney and cannot extend it, the Matrix or Inspire at 12 ft is the more honest choice.
Tell us your square footage and your chimney height and we will tell you whether the 3500 is right or whether you are better served by a smaller stove — (540) 212-9374.
| Data expressed in inches. 1 inch = 25.4 mm (Single Wall Pipe / Double Wall Pipe) | Single Wall Pipe | Double Wall Pipe |
|---|---|---|
| Clearance – Back Wall | 13" | 6" |
| Clearance - Corner | 7 1/4" | 7" |
| Clearance - Side Wall | 14" | 14" |
| Clearance - Top (Measured From the Platform on Which the Appliance Is Installed) | 84" | 84" |
Q: Do I need a floor protection under and around my heater?
A: Yes, floor protection is required for any wood appliance unless the unit already sits on a non-combustible surface. You have many choices, such as stone, brick, cement board, or tile. You need to consult your owner's manual in order to know the dimensions of the floor protection specific to your model. In Canada, the floor protection must extend in front of the unit by at least 18 inches and by at least 8 inches on each side. In the USA, the floor protection must extend at least 8 inches on each side of the appliance (measured from the door opening) and at least 16 inches in front of the door opening.
Q: Can I vent my heater using an existing masonry chimney?
A: It is possible to install a heater using your existing masonry chimney. The chimney must comply with the building code of your country, state or province. It usually needs to be lined with refractory bricks, metal, or clay tiles sealed together with fire cement. The diameter of the chimney must be the same as the appliance's flue outlet. If your masonry chimney does not have the same diameter as the appliance's flue outlet, you need to insert a stainless steel liner having the proper diameter. Otherwise, you may face draft problems. There are two types of liners: rigid and flexible liner. Both types are made of stainless steel. They must be certified for venting solid-fuel burning appliances. Flexible liner is particularly useful when the masonry chimney has one or more deviations.
Q: What Payment Methods Do You Accept?
A: We accept all major credit and debit cards (Visa, MasterCard, American Express, Discover), Apple Pay, Google Pay, and Link by Stripe for one-click checkout.
Q: Can I Cancel or Modify My Order?
A: For ready-to-ship items, contact us immediately if you need to cancel or modify. We'll do our best to accommodate if the order hasn't shipped yet. For custom-made, made-to-order, and special order items, these are final sale and cannot be canceled or modified once production begins or the order is submitted to the manufacturer. Please double-check your order details before completing your purchase.
Q: Why Choose First Response Fireplace Products?
A: We bring years of specialized expertise to the fireplace industry. When you choose us, you're getting the knowledge and experience that comes from being dedicated fireplace industry experts.
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