Choose Gas Log Sets by Fireplace, Fuel and Fit

A gas log set combines non-burning imitation logs with a gas burner and its approved controls and decorative media. The gas makes the flame; the logs provide the wood-fire appearance. It is a system, not just a stack of replacement logs. For example, Real Fyre’s complete-system diagram includes logs, a grate, burner pan, embers, fuel-specific burner media and controls. Some components are sold separately. Real Fyre vented catalog

Choose the fireplace-compatible burner system first, then the log style. The useful buying order is fireplace approval, vent type, fuel, clearances and dimensions, followed by controls and appearance.

Vented and vent-free gas log sets

The two main categories differ in where combustion products go—not simply in whether you happen to open the damper.

Type	Installation requirement	Main buying consideration
Vented gas logs	An approved wood-burning fireplace with a functioning chimney or flue.	A decorative fire with some radiant warmth; its fuel-input rating is not its room-heat output.
Vent-free gas logs, also called ventless or unvented	A fireplace or firebox approved for that set, local permission, and adequate combustion and ventilation air.	More heat delivered indoors, but combustion products and water vapor also enter the living space.

Real Fyre’s selection guide describes the two categories and their fireplace requirements. Its G45 vented set is certified as a vented decorative appliance, with input ratings stated in BTU per hour. Its G18 vent-free manual identifies that model as a supplemental heater, not a primary heating source, and warns about moisture during extended operation. Selection guide, G45 manual, G18 manual

Vent-free does not mean emission-free. EPA identifies carbon monoxide, nitrogen dioxide and particles as important pollutants from combustion sources and advises special precautions with unvented gas heaters. Indoor-air considerations belong in the purchase decision, especially where occupants have respiratory disease. EPA combustion-products guidance

Closing a vented set’s damper does not convert it to vent-free. The G45 instructions require a permanent minimum damper opening and a fully open damper during operation. Some sets, including the G18, are certified for both vent-free and vented use, but only under the installation conditions specified for each configuration. G45 instructions, G18 instructions

A log set is not a gas insert

A gas log set uses the approved fireplace or firebox as its enclosure. A direct-vent insert is a separate appliance fitted into the fireplace, with its own firebox components, viewing glass and specified intake/exhaust venting. Real Fyre direct-vent insert manual

If room heating is the main goal, compare a listed fireplace heater or insert before committing to decorative vented logs. That is a different project; our gas fireplace insert cost guide covers its budgeting scope.

Five checks before ordering

1. Identify the fireplace and its permission to accept logs

For a factory-built fireplace, record the manufacturer and model from its label and find its manual. For masonry, arrange an assessment of the firebox and chimney rather than assuming that an existing opening is suitable.

The proposed log set’s instructions and the existing fireplace’s instructions must both permit the installation. The G18 manual, for example, prohibits installation in a factory-built fireplace whose instructions say it has not been tested or should not be used with unvented burner systems. Both the G45 and G18 manuals require cleaning and inspection of an existing solid-fuel fireplace before installation; repairs may be necessary. G18 fireplace requirements, G45 pre-installation requirements

Stop here if fireplace compatibility cannot be established. A gas connection in the firebox is not proof of approval.

2. Confirm the fuel and gas-supply capacity

Order for the verified supply: natural gas or propane. Do not infer the fuel from the appearance of the logs, the connector or the control knob.

The G45 and G18 models cited here are not field-convertible to another gas. Their rating plates must match the supply. Have the installer verify pipe capacity and operating pressure for the chosen input rating; an existing line is not automatically sufficient for a larger burner. G45 gas-supply requirements, G18 manual

3. Measure the usable firebox—not just its front opening

Record:

• Front width and rear width.
• Usable depth and height, including any difference between front and rear height.
• Any raised ash lip, recessed floor or door-frame obstruction.
• Mantel height and projection, nearby combustible trim and flooring.

Compare those measurements with the exact burner, log size and control configuration. Nominal log length is not the minimum fireplace width.

For example, the G45-24 specification table requires at least 34 inches front width, 28 inches rear width, 13 inches depth and 17 inches height. Its 02 control models require another 2 inches in both widths. Rear width is measured at the specified depth, and depth begins inside an ash lip where one exists. This manual also prohibits an ash lip or recess greater than 3/4 inch. These are model-specific requirements, not a universal sizing rule. G45 specification table, page 6

4. For vent-free, check the room as well as the fireplace

Confirm permission with the local building authority before buying. Then have the installer assess room volume, other combustion appliances, air supply and the building’s tightness—not just floor area.

The G18 manual’s combustion-air calculation includes the aggregate appliance input in the space and addresses unusually tight construction. Its mantel and combustible-clearance requirements are separate from the minimum firebox dimensions. A set can fit inside the opening and still be unsuitable for the installation. G18 ventilation and clearance requirements, pages 9–11

5. Choose controls and approved logs together

Available controls can include match-light, manual standing-pilot, remote on/off, variable flame and electronic ignition. Availability depends on the burner and fuel. In Real Fyre’s range, match-light is a natural-gas option; remote functions vary by valve package. Control-selection guide, Vented catalog

Do not mix unrelated logs, burners or ember materials because they look compatible. The manufacturer’s approved combinations and placement instructions matter. The G18 manual warns that incorrect log positioning or additional embers can cause unsafe operation; its flames should not strike the logs when they are correctly placed. G18 media-placement instructions, pages 18–19

What the installation quote should identify

Ask for the exact burner model, fuel, log style and size, control package, installation manual, required fireplace or chimney repairs, gas work, and applicable permit or inspection requirements. Confirm whether the price includes the logs as well as the burner—both cited Real Fyre manuals show separately purchased log sets.

Have a qualified installer complete and commission the system, and retain both the burner manual and log-placement instructions. A quote that names only “24-inch gas logs” leaves too much of the appliance unspecified. G45 manual, G18 manual