Monessen Mountain Oak Vent Free Gas Log Set — Four- or Five-Log Stack, 18", 24" or 30" with the Lumonessen Burner
Every variant on this page is a complete vent-free set: the hand-painted Mountain Oak logs — four in the 18" set, five in the 24" and 30" — on the Monessen Lumonessen burner, with the volcanic rock, rock wool, anchor screws and shutoff valve in the carton. One burner size carries all three log sizes at 38,000 BTU/hr on natural gas or propane. Pick manual control — a piezo-lit pilot and a HI/LO knob — or the self-powered millivolt valve with its on/off switch, the RCB on/off remote, or the TSST thermostatic remote; nothing on this page needs a power outlet. from $608, with a 5-year parts warranty on the burner and logs.
Choose it if you want the simplest Classic Series stack — the fewest logs of the three sets on this burner, so more of the flame and the glowing rock wool stay in view — for an existing masonry or factory-built fireplace or a Monessen Exacta, Attribute or Lo-Rider vent-free firebox, and you want to size the set to the opening: 25" of front width for the 18" set, 29" for the 24", 33" for the 30", all at 13" deep and 17" high. It is the set to pick over the Natural Blaze sets when the firebox is shallow — 13" of depth is all it asks.
It is not right as a primary heat source — the manual approves it as a supplemental room heater or decorative appliance, and an unvented burner puts moisture into the room. It cannot go in a bedroom or bathroom, in a fireplace whose instructions exclude unvented gas logs, or behind glass doors that will be closed while it runs. The room also has to be big enough — 50 cubic feet for every 1,000 BTU/hr of gas appliances in it — and above 2,000 feet the input is derated 4% for each 1,000 feet of elevation measured from SEA LEVEL, so 12% at 3,000 feet. If you want a fuller, taller stack of logs on the same burner, the six-log Mezmer and Mezmer Split are the ones to compare.
Specifications
The minimum hearth for the burner with its logs is 25" wide at the front, 13" deep and 17" high with a 17-1/2" rear width for the 18" set; the 24" set needs 29" at the front and 19-1/2" at the rear, the 30" set 33" and 25-1/4", both at the same depth and height. Sidewalls stay 9" from the sides of the fireplace opening and the ceiling 42" above it; the wall directly above the opening must be heat-resistant material for at least 12" (8" to 12" with a hood), and a combustible mantel sits 14" to 28" above the opening depending on how far it projects — 8" to 26" with the CABL canopy. The burner sits at least 1-3/8" above carpet or vinyl that comes within 14" of the fireplace base, or the floor in front is 14" of slate or marble. In a vent-free firebox the firebox manufacturer's clearances govern. Inlet pressure runs 5" to 10" W.C. on natural gas and 11" to 13" W.C. on propane; each burner is built for one gas and cannot be converted in the field.
Mountain Oak vs. the Mezmer and Mezmer Split
All three Classic Series sets ride the same Lumonessen burner, so the ratings, controls, hearth minimums and clearances on this page are the same on the other two. The Mountain Oak is the simpler stack — four logs in the 18" and five in the 24" and 30" — where the Mezmer and the Mezmer Split each build six logs into a fuller bark-style pile in the same three sizes. This Mountain Oak set starts at from $608; the Mezmer at from $608 and the Mezmer Split at from $608.
Features
- Mountain Oak logs in 18", 24" or 30" — four hand-painted logs in the 18" set, five in the 24" and 30", with ridges that lock the lower three to the Lumonessen burner frame; volcanic rock and rock wool embers in the carton
- 38,000 BTU/hr on natural gas or propane from one burner size that fits all three log sizes
- No electricity needed — manual control with a piezo-lit pilot and HI/LO knob, or the self-powered millivolt valve that takes an on/off, thermostatic or wall control
- Vent free with an ODS safety pilot; the millivolt sets are also listed for vented use with the damper clamped open
- Goes into a masonry fireplace, a UL127 factory-built fireplace or a listed vent-free firebox — Monessen pairs the 18" with its 32" fireboxes, the 24" with the 36s and the 30" with the 42s
- 5-year parts warranty on the vent-free burner and logs
Answers to common questions
Does it need a chimney, a vent or an outside air kit?
No — every set on this page is an unvented room heater that burns room air, so it needs no flue.
The millivolt
sets are also listed (in the U.S.) as vented decorative log sets, so if your fireplace can't meet the vent-free wall or mantel clearances you install one of those and run it with the damper clamped fully open instead — a thermostat is not allowed in that case. Either way it goes into a solid-fuel masonry fireplace, a UL127 factory-built fireplace or a listed vent-free firebox, and the room must give it 50 cubic feet of volume for every 1,000 BTU/hr of gas appliances in it.
What size fireplace opening do I need, and which Monessen fireboxes take it?
Measure the hearth the burner and logs will sit in. The 18" set needs 25" of front width, 13" of depth and 17" of height with 17-1/2" across the back; the 24" set needs 29" at the front and 19-1/2" at the back; the 30" set 33" and 25-1/4" — the depth and height stay the same. If a glass-door frame or a recessed hearth stands up to 3" in front of the set and it is installed vented, plan on 16" of depth instead. Monessen's own vent-free fireboxes pair the 18" set with the Exacta 32 and Attribute 32, the 24" set with the Exacta 36, Attribute 36 and Lo-Rider 36, and the 30" set with the Exacta 42, Attribute 42 and Lo-Rider 42.
How close can a mantel or the ceiling be?
The clearances are the same for every set on this page. The ceiling must be at least 42" above the top of the fireplace opening and combustible sidewalls at least 9" from its sides; the wall directly above the opening must be heat-resistant material (slate or marble at least 1/2" thick) for at least 12" — 8" to 12" is allowed with a hood such as the CABL canopy. A combustible mantel projecting 10" or less needs 28" above the opening with no hood — one height, whatever the depth. Fitting the hood is what buys that back — 2-1/2" of projection is then allowed at 8", 6" at 14-1/2", 8" at 18-5/8", 10" at 22-1/2" and 12" at 26". See Figures 3.5 and 3.6 on page 11 of the installation manual for the full profiles. If your fireplace can't meet them, a millivolt set is installed and run vented with the damper open. In a Monessen vent-free firebox, the firebox's own clearances apply.
What’s included, what’s required, and what’s optional?
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Included in the box: Mountain Oak log set — four hand-painted logs (18") or five (24" and 30"); Lumonessen vent-free burner with ODS safety pilot, piezo igniter, two anchor screws, 1/2" T-handle shutoff valve and flexible gas connector, and the installation/owner manual; Two bags of crushed volcanic rock and the rock wool ember material; Listed to ANSI Z21.11.2 (unvented room heater) and ANSI Z21.60 (decorative, U.S.).
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Required to complete the installation, purchased separately: Gas line - a natural gas or propane line to the fireplace run by a qualified installer, with an external regulator for propane or wherever supply pressure exceeds 1/2 psig; A fireplace or firebox to house it - a solid-fuel masonry fireplace, a UL127 factory-built fireplace or a listed vent-free firebox whose hearth meets the minimum dimensions for the size chosen.
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Optional: CABL adjustable canopy to reduce the wall and mantel clearances, MVWS wired wall switch or RRCM insulated receiver cover for the millivolt models - the set operates fully without them.
Will it work in a power outage?
Yes, on every variant — nothing on this page uses house current. The manual-control burner has a piezo igniter and a knob; the millivolt burner lights the same way and runs on its own thermopile, and the RCB and TSST remotes are battery powered, so a dark house still gets a fire.
Which control should I pick, and what does each remote do?
All four choices light the same burner and logs; they differ in how you run it. "Standing Pilot - Manual" is the manual-control burner: you press the piezo to light the pilot and turn the knob between HI and LOW at the fireplace — no switch, and no remote or thermostat can be added later. The three millivolt choices add the self-powered millivolt valve with its on/off switch: "Manual" gives you the switch alone, "On/Off Remote" adds the RCB battery remote, and "Thermostatic Remote" adds the TSST touch-screen thermostat remote with its TS sensor so the set holds a room temperature (unvented installations only — a thermostat is not allowed when the set is run vented). Any millivolt set also accepts the MVWS wired wall switch.
How are the logs placed, and why does it smell on the first burn?
The sheet packed with the set walks through it: the rear log goes on the rear support, the middle log on the middle support, the front log between the burner and the grate — those three have ridges underneath that lock them to the burner frame — and then the top log (18") or the top right and top left logs (24" and 30") rest in the cutouts of the logs below. Volcanic rock goes on the fireplace floor only, never on the burner, pilot or logs, and you never add extra logs, pine cones, vermiculite or rock wool. The smell is the break-in: new logs and rock wool give off a paper-burning odor and orange flames for the first few hours — run it on high with the windows open, then let each later lighting preheat 15 minutes and check that no yellow flame touches a log. Annual cleaning by a service technician keeps the pilot and burner ports clear; you brush or vacuum the logs yourself, never with cleaning fluid.
Does buying from The Torch Guys affect my Monessen warranty?
No. HHT's warranty covers Monessen products bought through an authorized dealer, and The Torch Guys is one — we register the set and, if you ever need to claim, we deal with the manufacturer on your behalf. The vent-free burner and logs carry 5 years on parts, purchased accessories such as the remotes 1 year, and the coverage transfers to a later owner of the home. Keep your invoice and the model number from the burner's rating plate; we hold the rest on file.
