Gas logs are the easiest way to upgrade your existing fireplace.
Gas logs come in two varieties: vented gas logs and vent-free gas logs. A vented gas log must be used in a regular fireplace, designed to burn a wood fire. Vent-free gas logs can be used in a regular fireplace or can be used in a prefabricated vent-free firebox that has no chimney.
To maximize heat output, choose a vent-free gas log set or a vented gas log set that specifically notes high heat production. While vented gas log produce a large, realistic flame, most vented options lose a large amount of heat up the chimney.