Ventless Gas Logs

Ventless gas logs burn cleanly enough to run without a chimney, so the heat stays in the room instead of going up a flue. This collection spans vent-free log sets and contemporary fire glass sets in natural gas and propane, for a wood-burning fireplace or a certified vent-free firebox.

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Ventless Gas Logs Need No Chimney, Just the Right Spot

A ventless gas log set, also called vent-free, burns cleanly enough for its exhaust to stay in the room. The damper stays closed, and the heat stays with you. What it does need is an approved place to sit. Real Fyre and Monessen certify their vent-free sets for two places. One is a masonry or factory-built wood-burning fireplace, unless that fireplace's manual excludes unvented burners. The other is a certified vent-free firebox framed into a wall that never had a fireplace. A former direct vent gas fireplace or a homemade opening is neither.

Size the Set to the Room, Not Only the Firebox

Because the combustion air comes from the room, the room has to be big enough. The National Fuel Gas Code, quoted in Real Fyre's manual, calls for at least 50 cubic feet for every 1,000 BTU of all the gas appliances in the space. Real Fyre works the example at 1,800 cubic feet, an 18 by 12.5 foot room with an 8 foot ceiling, which covers 36,000 BTU. Rooms joined by an opening with no door count toward the total.

Bedrooms, Bathrooms and Local Codes Set Hard Limits

The vent-free heater standard, ANSI Z21.11.2, keeps any set over 10,000 BTU out of a bedroom and any over 6,000 BTU out of a bathroom, as Real Fyre's manual spells out. Real Fyre's 9,500 BTU set sits under the bedroom limit and can go in a bedroom where local code allows, while Monessen's Mojo manual rules out bedrooms and bathrooms entirely. Beyond room-by-room limits, some states and cities restrict vent-free appliances altogether, California and parts of Massachusetts among them, so check your local code before you order.

Vent-Free Heat Is Supplemental and Adds Moisture

Real Fyre and Monessen both call their vent-free sets supplemental heat, not a primary heat source. Burning gas also makes water vapor, and with no flue it stays in the house. Monessen notes this is not a problem in most homes of average construction. Real Fyre advises opening the damper or a window if condensation starts to form after long runs.

Tight Mantel Clearance Means Running It Vented

Vent-free sets publish minimum clearances to a mantel and to combustible side walls, and Monessen's Mojo wants the sides of the opening at least 16 inches from combustible material. When a fireplace cannot meet the clearances, both Monessen and Real Fyre say the set must run with the chimney damper open, as a vented appliance. Measure the mantel height before you choose ventless for its heat.

Explore Related Gas Logs

Looking for something else? Browse the rest of the gas log range:

Gas Fireplace Log Sets, vented and ventless in one place
Ventless Gas Logs With Remote, on/off, variable flame and electronic ignition remotes
Most Realistic Ventless Gas Logs, charred finishes and glowing ember beds
Vented Gas Logs, for a fireplace with a working chimney
Natural Gas Log Sets and Propane Gas Log Sets, by fuel

Frequently Asked Questions about Ventless Gas Logs

Are ventless gas logs safe?

They are certified as unvented room heaters and carry an oxygen depletion sensor pilot that shuts the burner off if the room's oxygen starts to drop. Safe use still depends on the limits: the right room size and no bedroom or bathroom installs above the code limits. Real Fyre's manual also warns against running the set unattended or while anyone is asleep.

Do ventless gas logs need a chimney?

No. They need an approved place instead: a masonry or factory-built wood-burning fireplace, or a certified vent-free firebox. If the fireplace cannot meet the set's mantel and side wall clearances, the manuals require running it with the damper open as a vented appliance.

How big does a room need to be for ventless gas logs?

At least 50 cubic feet for every 1,000 BTU of all the gas appliances in the room, per the National Fuel Gas Code as quoted in Real Fyre's manual. A 36,000 BTU set needs 1,800 cubic feet, about an 18 by 12.5 foot room with an 8 foot ceiling. Rooms joined by an opening with no door count toward the space.

Can ventless gas logs go in a bedroom?

Only small ones. ANSI Z21.11.2 keeps sets over 10,000 BTU out of bedrooms and over 6,000 BTU out of bathrooms. Real Fyre's 9,500 BTU set can go in a bedroom where local code allows, while Monessen's Mojo manual rules out bedrooms and bathrooms entirely.

Do ventless gas logs cause condensation?

They can, because burning gas makes water vapor and a vent-free set keeps it in the house. Monessen says this is not a problem in most homes of average construction. Real Fyre adds that a tightly built home or a high altitude raises the heat and moisture, and advises opening the damper or a window if condensation forms.

Are ventless gas logs legal in my state?

It depends on the state and the city. Vent-free gas appliances are restricted or prohibited in some places, California and parts of Massachusetts among them, and some local codes also limit the BTU rating by room size. Check with your local building department before you order.