Monessen Mezmer Split Vent Free Gas Log Set — 18", 24" or 30" with the Lumonessen Burner
Every variant on this page is a complete vent-free set: six hand-painted Mezmer Split logs on the Monessen Lumonessen burner, with the grate, two bags of volcanic rock, rock wool, anchor screws and the T-handle shutoff and flex connector in the carton. One burner size carries the 18", 24" and 30" sets, at 38,000 BTU/hr on natural gas or propane. Pick the manual control — a piezo-lit standing pilot and a Hi/Lo knob — or the millivolt valve with its on/off switch, alone or with 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 split-face look in the Lumonessen Classic Series — the same six-log stack and placement as the Mezmer bark set, with the two top logs swapped for split pieces — in an existing masonry or factory-built fireplace or a Monessen Exacta, Attribute or Lo-Rider vent-free firebox, sized 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 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; a glass-door frame or recessed hearth that stands more than 3" in front of the set is not recommended at all. The room also has to be big enough — 50 cubic feet for every 1,000 BTU/hr of gas appliances in it, about 1,900 cubic feet at full input — 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.
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. A restrictive barrier of up to 3" in front of the set raises the minimum depth to 16". Sidewalls stay 9" from the sides of the fireplace opening and the ceiling 42" above it; the wall above the opening needs heat-resistant material for at least 12" (8" to 12" with a hood), a combustible mantel sits 14" or more above the opening depending on how deep it is, and the burner sits 1-3/8" above carpet or other combustible flooring within 14" of the fireplace unless 14" of non-combustible material lies in front. 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.
Mezmer Split vs. the Mezmer and Mountain Oak sets
All three Classic Series sets ride the same Lumonessen burner, in the same three sizes with the same ratings, controls and remotes — the difference is the logs. Mezmer is the bark-faced set and Mezmer Split its split-face twin: the same six-log stack, the same placement and the same middle log, with the two top logs swapped. Mountain Oak is a four-log stack in 18" and five logs in 24" and 30". This Mezmer Split set starts at from $608; the Mezmer set starts at from $608 and the Mountain Oak set at from $608.
Features
- Six hand-painted split-style logs in 18", 24" or 30" — the split-log companion to the Mezmer bark set, on the one Lumonessen burner that fits all three sizes
- 38,000 BTU/hr on natural gas or propane, with a Hi/Lo control to turn it down as low as 19,000 (manual, natural gas) or 27,000 to 31,000 BTU/hr
- No electricity needed — a piezo lights the standing ODS pilot, the manual valve is all mechanical and the millivolt valve powers itself
- Vent free with an ODS safety pilot, and dual rated for vented use with the damper clamped open — in a masonry fireplace, a UL127 factory-built fireplace or a listed vent-free firebox
- Volcanic rock, rock wool, grate, anchor screws and the T-handle shutoff with flex connector come in the burner carton
- 5-year parts warranty on the burner and logs, transferable to a later owner of the home
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. It is also listed (in the U.S.) as a vented decorative log set, so if your fireplace can't meet the vent-free wall or mantel clearances you install and run it with the damper clamped fully open instead. Either way it goes into a solid-fuel masonry fireplace, a UL127 factory-built fireplace or a listed vent-free firebox, a damper stop goes on any fireplace damper so it can never close fully, 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 because it is the same burner under every size. If a glass-door frame or a recessed hearth stands up to 3" in front of the set, 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 needs heat-resistant material such as slate or marble for at least 12" (8" to 12" is allowed with a hood). A combustible mantel needs at least 8" of heat-resistant material under it and a height that depends on whether a hood is fitted — without one, a mantel projecting 10" or less sits at 28" above the opening over 12" of heat-resistant material, whatever its depth; with the hood the manual's examples put a 2-1/2" mantel at 8" and a 6" mantel at 14-1/2". The full profiles are Figures 3.5 and 3.6 on pages 10-11 of the installation manual, and you can send us your mantel depth. If your fireplace can't meet them, the set is 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?
-
Included in the box: Mezmer Split log set — six hand-painted logs; Lumonessen vent-free burner with heavy grate, T-handle shutoff valve and flexible gas connector, two anchoring screws and the installation/owner manual; Two bags of crushed volcanic rock and rock wool ember material; Piezo-lit standing ODS pilot with a manual Hi/Lo control knob, or the millivolt valve with its on/off switch; the RCB or TSST remote your Ignition choice names; Listed to ANSI Z21.11.2 (unvented room heater) and ANSI Z21.60 / CSA 2.26 (vented decorative appliance, U.S.).
-
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 on every propane system and 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.
-
Optional: C-CLAMP damper clamps (carton of 6) - only if the fireplace forces you to run it vented. Vent-free, the set works without them and the damper stays under your control; if the wall or mantel clearances cannot be met the manual sends you to a vented installation with the chimney and damper open, and there the clamps are required; A wall switch or wall thermostat on the millivolt valve, and heat-resistant facing or a hood where the wall above the opening is short of 12" of non-combustible material — the set operates fully without them.
How do the logs go on, and does placement really matter?
Yes — the same five steps for every size, and the manual calls the positioning critical. The rear log goes on the rear support, the front log between burner and grate against the tab on the right, the middle log on its support with a corner in the front log's notch, the top right log across the front and middle logs, and the two split top logs across the middle and back logs; the three bottom logs have ridges that lock them to the burner frame. Volcanic rock goes on the fireplace floor only, never on the logs, pilot or burner. After a 15-minute warm-up you check that no yellow flame is touching a log — logs set off the diagrams can soot.
Will it work in a power outage?
Yes, on every variant — nothing on this page uses house current. A piezo button lights the pilot, the manual-control valve is all mechanical, and the millivolt valve runs on its own thermopile with the on/off switch, remote or thermostat wired at low voltage to the valve, 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: a piezo lights the standing pilot and a Hi/Lo knob on the valve sets the flame — no switch, no remote, and no way to add one later. The three millivolt choices share 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 it is run vented). A wall switch or wall thermostat can also be wired to the millivolt valve.
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, the gas electrical parts such as the valve, pilot and remote 2 years, purchased accessories 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.
