Osburn Horizon EPA 2020 Wood Burning Fireplace
Up to 11 hours on one load. The Osburn Horizon (OB04010) is the largest of Osburn's three EPA 2020-certified wood fireplaces: a 4.28 ft³ usable firebox rated up to 95,000 BTU/hr on dry cordwood at 70% optimum efficiency and 1.6 g/h, for 1,000 to 2,800 square feet. It frames 50-3/4" wide by 26-7/8" deep with zero clearance to the enclosure, vents through an 8-inch Class A chimney, takes 25-inch logs behind cast-iron double doors with a 29-3/4" x 13-1/2" view, and ships with its 176 CFM variable-speed blower and automatic air control. The Prairie style faceplate and the classic moulded brick panels complete it above and are priced on top; from $5,824 for the fireplace alone.
Choose the Horizon if you heat a large open space with wood and want the longest burn Osburn offers: the 4.28 ft³ firebox takes 16-inch pieces north-south five to eight at a time, the blower is already in the box, and once you close the primary air the automatic control trims the burn for you, with a lever for low or medium heat. The Prairie style faceplate frames a pair of arched glass panes in cast-iron doors, and the 6-inch forced-air outlets on either side take Osburn's forced-air kit when you want heat in another room up to 50 feet away. The faceplate and the brick panels are required, not decorative, and each is priced on top of the fireplace.
It is not right for a small room or a home that needs a modest fire: this is a 4.28 ft³ firebox rated for 1,000 to 2,800 square feet, and its chase is 50-3/4" wide. It is not for a mobile home in Canada or a manufactured home in the USA, not for an alcove, not for open-door fires — the doors stay closed and latched — and not for a gas log set. It needs an 8-inch listed chimney at least 15 feet tall, an 84-inch ceiling above its base with nothing combustible over the fireplace (a shelf above it must be non-combustible and 52 inches up), 48 inches clear of anything combustible in front of the opening, and a 32-inch deep non-combustible floor in front when it sits on the floor — it cannot sit inside a masonry fireplace, and an existing masonry chimney serves it only relined with an 8-inch stainless liner. If you want a combustible wood mantel across the top, the Horizon does not allow one.
Specifications
Frame the chase 50-3/4" wide and 26-7/8" deep, add the thickness of your facing, and leave the space above the fireplace empty to 84" from its base; with the fresh-air intake add 6" on the right and with the forced-air kit add 10" on the side it uses. The back, sides and floor of the enclosure are zero clearance; the chimney keeps 2". A combustible side mantle may project up to 6" and sits at least 8" from the door opening; a combustible side wall stays 24" from the opening; anything combustible in front, the facing wall included, stays 48" from the opening. Nothing combustible goes above the fireplace, and a shelf there is non-combustible and at least 52" above the base. Floor protection is 49" wide and 32" deep at R 2.00 when the fireplace sits on the floor or a base under 8"; on a base over 8" it is 16" deep, on a base between 8" and 12" it is 20" deep at R 1.00, and over 12" it is 16" deep with no R-value. The chimney is an 8" CAN/ULC S629 / UL 103 HT system from the approved list on an 8" anchor plate — at least 15 feet from the base to the top and at least one support; Osburn recommends 18" of straight pipe before the first offset but also approves starting with a 30° or 45° elbow. The blower and the automatic air control are hard-wired by an electrician; in a power failure the air supply closes by hand.
Features
- EPA 2020-certified non-catalytic firebox: 1.6 g/h emissions, 70% optimum efficiency, up to 95,000 BTU/hr on dry cordwood and up to 11 hours per load
- Cast-iron double doors with arched ceramic glass and a 29-3/4" x 13-1/2" view behind the Prairie style faceplate
- 176 CFM variable-speed blower is in the box, already wired behind the faceplate with AUTO and manual modes
- 4.28 ft³ usable firebox takes 25-inch logs (16-inch recommended, loaded north-south) and is rated for 1,000 to 2,800 ft²
- Zero clearance to the enclosure at the back, sides and floor; frames 50-3/4" wide x 26-7/8" deep under an 84-inch open chase
- Ready for a 5-inch fresh-air intake (adapter and block-off plate in the box), a forced-air kit on either side and the warm-air circulation grille
Answers to common questions
What chimney does the Horizon need, and is any of it included?
None of the chimney is in the box. The fireplace vents through an 8-inch factory-built chimney listed to CAN/ULC S629 / UL 103 HT (2100 °F) from Osburn's listed-chimney table (Table 4, page 58 of the installation manual) — DuraVent Dura Tech, Dura Tech Premium, Dura Tech Canada DTC, Dura Plus and Dura Plus HTC, Selkirk CF Sentinel, Super Pro 2100 and Super Vent 2100, Security S-2100+, Olympia Ventis, Nexvent, Champion and Rockford, Metal Fab Temp Guard, American Metal HS and HSS — starting with an 8-inch anchor plate on the fireplace, sold separately. Plan on at least 15 feet from the base of the fireplace to the top (17 feet with four offsets), at least one support, 2 inches of clearance around the pipe, 3 feet above the roof and a rain cap — Osburn recommends 18 inches of straight pipe before the first offset but also approves starting with a 30° or 45° elbow; some brands also require their ventilated roof flashing or an insulated attic shield. A masonry chimney works only relined with an 8-inch stainless liner through the chimney maker's 30° or 45° connector. The chimney maker's instructions govern the run itself.
How close can a mantel, a shelf or a side wall be?
Nothing combustible can sit above the fireplace: the space over it stays empty for 84 inches from the base, and a shelf there must be non-combustible and at least 52 inches above the base. At the sides, a combustible side mantle or pilaster may project up to 6 inches and must sit at least 8 inches from the door opening, and a combustible side wall stays 24 inches from the opening. In front, keep furniture and any combustible wall at least 48 inches from the opening. The facing directly in front of the fireplace is non-combustible for the full 84 inches and extends 3 inches beyond one side of the unit and 3-1/16 inches beyond the other. Send us your surround drawing if you want it checked — we're here to help!
What goes on the floor in front of it?
A continuous non-combustible surface 49 inches wide — 8 inches past each side of the door opening — such as ceramic on a non-combustible sheet, cement board or brick, never over carpet. How deep it is and what R-value it needs depend on how high the fireplace sits: directly on the floor or on a base under 8 inches, 32 inches deep at R 2.00 (4 inches of brick plus 1 inch of Durock gets you 1.32, so plan the build-up); on a base over 8 inches, 16 inches deep at R 2.00; between 8 and 12 inches up, 20 inches deep at R 1.00; over 12 inches up, 16 inches deep with no R-value. A bent continuous metal strip protects the joint between the protection and the fireplace, and it is not supplied.
What’s included, what’s required, and what’s optional?
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Included in the box: The fireplace body with its C-Cast baffle and four stainless secondary air tubes, inner ash retainer and ash lip; 176 CFM variable-speed blower with rheostat and AUTO/MAN switch, mounted behind the faceplate at the bottom; Double cast-iron doors with arched 4 mm ceramic glass; Automatic air control with its auxiliary lever, plus the side and back standoffs with their screws in the owner's manual kit; 5-inch fresh-air adapter, air-inlet block-off plate and screws (for the optional fresh-air intake); EPA 2020 certification, ULC S610 / UL 127 listing and the Osburn limited lifetime warranty.
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Required to complete the installation, purchased separately: Faceplate - the Prairie style faceplate that frames the doors; it hooks onto springs at the top of the fireplace, is screwed at the bottom and overlaps your facing, so it stays removable; Interior Panel - the classic moulded refractory brick panels that line the firebox; they come in their own box and go in after the fireplace is set in place; Venting - an 8" listed factory-built chimney from the approved list (see pg 58 in the installation manual) or a lined masonry chimney; Floor Protection - a continuous non-combustible surface 49 inches wide and 32 inches deep in front of the fireplace at R 2.00 when it sits on the floor or on a base raised less than 8 inches (less depth only on a base raised more than 8 inches, see the options table on page 37 of the installation manual), with a bent metal strip at the joint; Electrical - a household circuit hard-wired by a qualified electrician for the included blower and the automatic air control, with the ground on the fireplace frame.
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Optional: The 5-inch fresh-air intake register, termination and insulated pipe, the forced-air kit and its 6-inch flex pipe, the warm-air circulation grille and ROBAX NightFlame glass — the fireplace burns wood fully without any of them.
Is the blower included, and does the fireplace need electricity?
The 176 CFM variable-speed blower is included, already mounted at the bottom of the fireplace behind the faceplate with its rheostat and AUTO/MAN switch; in AUTO it starts when the fireplace is warm and stops when it cools. The fireplace is hard-wired by a qualified electrician, with the ground on the fireplace frame — the supply runs the blower and the automatic air control that trims the burn once you close the primary intake. In a power failure the fire keeps burning: you close the air supply by hand with the small lever, and only the blower and the automatic trimming stop.
Do I need an outside air kit?
Usually not by law — some US jurisdictions require outdoor combustion air, and a Novo Climate or R2000 home needs it — but Osburn strongly recommends one, and the fireplace ships with the 5-inch adapter, block-off plate and screws for it. To connect outside air you add an insulated HVAC-class duct — 5-inch for a run under 20 feet, 6-inch for a run over 20 feet or with more than two bends, never more than 30 feet, and Osburn recommends at least 10 feet with a P-trap loop against condensation (the 25-foot 5-inch pipe is for a run under 20 feet, not its full length) — the outside wall termination with its clamps, and the register with an airtight damper, so the intake closes when the fire is out. The intake connects on the right side of the fireplace or under it on the right, and the termination goes outside above the snow line, away from exhausts, no more than 10 feet above or 3 feet below the base of the fireplace.
How long does it burn, and what size wood does it take?
Up to 11 hours on a full load of dry cordwood, in Osburn's rating. The firebox holds 4.28 ft³ of usable volume and takes logs up to 25 inches loaded east-west, but the fireplace is designed to burn best with 16-inch pieces loaded north-south — ends facing you — five to eight at a time on a raked coal bed, never raised on a grate or andirons. Fire each load hot with the air fully open, then close the primary intake and let the automatic control carry the burn; the auxiliary lever picks low or medium heat. Burn only seasoned wood at 15 to 20% moisture — the warranty is void on anything but cordwood.
Does buying online affect my Osburn warranty?
No. The warranty is Osburn's and runs from your dated purchase invoice, so keep it and register the fireplace online at osburn-mfg.com with the serial number from the nameplate on the back of the unit. The Torch Guys will help you with any claim. Coverage is a limited lifetime on the combustion chamber welds and cast-iron door frame (5 years labour) and on the ceramic glass, 7 years on the C-Cast baffle and secondary air tubes, 5 years on the handle, glass retainers and air control, 2 years on the blower and controls, and 1 year on paint, gaskets and firebricks. It requires installation by an authorized qualified technician, covers the original purchaser only, and is void if anything but cordwood is burned.
