Monessen Lo-Rider 36" See Through Vent Free Gas Firebox — Two Rooms, One Fire, No Chimney
A see-through vent-free firebox with a 36" x 30-3/4" opening on each face — no chimney, no vent run, and the same fire from both rooms. The Monessen Lo-Rider See-Through is the enclosure half of a two-sided vent-free fireplace: it complies with ANSI Z21.91 and hosts a listed vent-free gas heater up to 40,000 BTU/hr, sold separately — the price book pairs it with the 27" Natural Blaze See-Through log set. Traditional stacked refractory firebrick, four mesh curtain screens with hide-away pockets, two black canopies and a junction box ship in the carton; the flush hearth sits at floor level like a masonry fireplace. $1,919, with a 20-year firebox warranty.
Choose the Lo-Rider See-Through if you want one fireplace opening in two rooms — a partition wall between a living room and a dining room or den — where a chimney or vent run is impossible or too costly. It frames into a 46" x 37-1/2" x 23" rough opening built before or after the box is set, sits directly on a wood floor, and takes the Natural Blaze See-Through log set you buy separately; it is the only see-through firebox in Monessen's vent-free line.
It is not right for a bathroom, or for a bedroom unless the heater you put in it is rated 10,000 BTU/hr or less — those limits come with any unvented gas heater, and it is supplemental heat, never a primary heat source. It burns room air and adds moisture to the room, so a very tightly sealed house that cannot spare combustion air or add mechanical ventilation is the wrong home for it. It never takes a wood fire or a vented log set, and it is not a single-sided box: if you only need one face, the Lo-Rider LCUF36 shares the opening for less and offers the interior-panel choices this one cannot.
Specifications
Frame a rough opening 46" wide by 37-1/2" high by 23" deep; the headers may rest on the firebox standoffs, and when centering the box on a wall use its 42" body width rather than the 45" flange-to-flange width — Figures 4.2 and 4.3 on page 11 of the installation manual dimension the framing. The firebox itself is 45" wide over the nailing flanges, 37-1/4" high and 24" deep. Inside, the floor is 33-1/2" wide and 19" deep with 27-3/4" of interior height — the numbers to check against a log set's minimum firebox size. Combustibles may touch the sides, back and bottom; keep a combustible side wall 6" from the inside of the opening, the ceiling 42" above it, any parallel wall 36" away and flammable objects 42" from either face. Combustible mantel and mantel-leg clearances depend on how far the mantel projects — see Figure 6.3 and Figure 6.4 on page 13 of the installation manual — and the supplied canopies must be installed for them to hold. Non-combustible facing may cover the painted metal face; carpet or asphalt tile within 14" of the base needs the inner floor 1" above it or 14" of slate or marble between them. The 1/2" gas line enters from either side; the junction box takes field-wired main power when the blower or light kit is added.
How the Lo-Rider See-Through compares to the single-sided Lo-Rider LCUF
All three Lo-Riders share the flush hearth, the 30-3/4"-tall opening, the clean louverless face and the heat-circulating box. The see-through opens 36" wide on both faces, frames 46" wide and ships only with traditional refractory firebrick, at $1,919; the single-sided LCUF36 shares the 36" opening but frames 42-1/2" wide and lets you pick multitonal brick or reflective black glass interior panels, from from $1,119; the LCUF42 opens 42" wide and frames 48-1/2", from from $1,199. Pick the see-through when the wall has a room on each side.
Features
- 36" x 30-3/4" opening on both faces — one vent-free firebox finishes two rooms, or an inside and an outside wall, with a mesh curtain screen for each side
- Vent-free enclosure to ANSI Z21.91 — no chimney, no vent run; hosts a listed vent-free gas heater up to 40,000 BTU/hr, sold separately
- Traditional stacked refractory firebrick on the sides and floor ships factory-installed, with two black canopies and a junction box in the carton
- Flush hearth and a tall opening on a self-contained heat-circulating box with a clean, louverless face
- Frames into a 46" x 37-1/2" x 23" rough opening; combustibles may touch the sides, back and bottom, and it sits directly on a wood floor
- Blower-ready and light-ready — the BLOTDL forced-air kit and the MONALST accent light kit wire through the included junction box
Answers to common questions
What’s included, what’s required, and what’s optional?
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Included in the box: 36" x 30-3/4" firebox opening, open on both sides; Traditional stacked refractory firebrick — two side panels and a hearth panel, factory-installed; Four mesh curtain screen panels on rods (two per face) with hide-away screen pockets; Two black canopies (hoods), one per face — must be installed; Junction box for the electrical hookup; Compliance with ANSI Z21.91-2017 (ventless firebox enclosures); 20-year firebox warranty (3 years labor).
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Required to complete the installation, purchased separately: Vent Free Log Set - this firebox pairs with one build only: the 27" Natural Blaze See-Through log set (natural gas or propane, millivolt); any listed vent-free heater up to 40,000 BTU/hr whose own minimum firebox size this box meets may be used — the firebox is the enclosure and burns nothing on its own; Gas Line - a 1/2" line to the left or right side access hole, with a shutoff valve upstream, run by a licensed plumber before the wall is closed.
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Optional: The BLOTDL forced-air blower, the MONALST accent light kit, and the AK22 outside air kit with ID4 or UD4 duct — the firebox operates fully without any of them; electrical power is only needed when the heater or an accessory calls for it. The manual also names a DLR36B door kit that the price book does not carry.
Does it need a chimney or a vent?
No — nothing about this firebox vents outside. The heater it hosts uses air from the room, so the installation must provide adequate combustion and ventilation air and stay out of drafts from exhaust fans, ceiling fans, return-air registers, windows and doors; an extremely tight home needs additional mechanical ventilation, and the optional AK22 outside air kit ducts combustion air in through the side of the firebox.
What interior does it ship with, and can I change it?
Traditional stacked refractory firebrick — two side panels and a floor panel — comes factory-installed; you remove the shipping brackets at the four floor corners and it is ready. There is no other interior for the see-through: the multitonal brick and reflective black glass panels Monessen sells are for the single-sided Lo-Rider only. The brick can be lifted out and the box run bare if you prefer.
Where can it go — and where can't it?
Any wall with a room on each side that can spare combustion air. Combustibles may touch the sides, back and bottom; keep a combustible side wall 6" from the inside of the opening, the ceiling 42" above it, any parallel wall 36" away and furniture, curtains and clothing 42" from either face. It sits directly on a wood floor; over carpet or tile it needs a metal or wood panel under its full footprint, and carpet or asphalt tile within 14" of the base needs the inner floor raised 1" or 14" of slate or marble between them. The heater cannot go in a bathroom and goes in a bedroom only at 10,000 BTU/hr or less.
How high must a mantel or shelf be?
It depends on how far the mantel projects: combustible mantel and mantel-leg clearances are charted in Figure 6.3 and Figure 6.4 on page 13 of the installation manual, the supplied canopies must be installed for those clearances to hold, and combustible material may contact the top of the firebox. Non-combustible stone or brick may cover the painted face as long as it does not overhang the opening. Send us your mantel depth and we will read the chart with you. Monessen publishes no television guidance for this firebox, so follow your TV maker's temperature limits.
Does it use electricity?
Only if something in it needs power. A junction box ships in the firebox; if you plan the BLOTDL blower or the MONALST accent light, a licensed electrician field-wires the main supply to the firebox at installation, and both kits go in before the vent-free heater and before the walls are closed. A millivolt heater on its own can run with no power at all.
How does the warranty work if something goes wrong?
Hearth & Home Technologies warrants the firebox for 20 years on parts and 3 years on labor, the refractory for 10 years on parts and 1 year on labor, and other parts for 1 year — valid only on a purchase from an HHT authorized dealer, at the original site, and transferable to a new owner within two years. The Torch Guys is an authorized Monessen dealer and handles the claim for you: keep your invoice and the model and serial numbers, and we deal with the manufacturer on your behalf rather than handing you a phone number.
