Most gas fireplaces use a top-mounted damper or a flue control knob located near the gas valve. The knob often has a simple icon: a circle with a line through it (closed) and a circle with a dot (open).
If you have a direct-vent gas fireplace, it uses a sealed combustion system—the flue is always open to the outside, but you might still have a manual shut-off. Check your owner’s manual, or be brave and search the model number online.
Remember: Never leave a gas fireplace unattended if you’re unsure about the flue. Carbon monoxide is odorless and serious. Install a detector nearby—it’s the smartest $20 you’ll spend.
