Most of the big box stores like lowes and menards sell cheap fireplace vents on their websites. You can also go to fireplace-vent.fireplacecheap.us
The recommended diameter for a vent pipe when installing a 6" vent for a gas fireplace is typically 6 inches.
It is important that you KEEP THE FIREPLACE VENT DAMPER OPEN when you are using it. FAILURE TO DO SO CAN LEAD TO CARBON MONOXIDE POISONING AND DEATH.
Is this an insert into a previous wood burning fireplace? Direct vent or vent free? BTUs?
no. you must have a flue that properly vents to the outside. you will burn your house down if you try to start a wood fire in a vent free fireplace.
Direct vent gas fireplaces can be purchased from a number of websites such as Amazon and Continental Fire Places. Prices can be compared amongst a number of websites to find the best deal.
Vent free fireplaces can be installed almost anywhere, refer to the model your are interested in, every vent free fireplace has it's own clearance requirements, including floor to ceiling (Never install a TV above a vent free fireplace!)
just look
IF you have a woodburning fireplace, and there is a small door- about 6 inches square on the outside of the house, check for a flip open door on the floor of your fireplace. If that is what you have, this is not a vent, but an ash clean-out. Shovel ashes thru the door on the floor of the fireplace, and you can remove them from the outside door without making a mess in the house. But not a vent. If that is not what you have, please post gain with a more detailed description.
A gas fireplace. It is designed to burn at about 99% efficency, and does not produce smoke or carbon monoxide, and is not vented to the outdoors.
flu (meaning sickness) flue (as in fireplace flue or vent)
A direct vent is definitely the safest way to vent a fireplace. It is also the least expensive.
To open the vent of a fireplace, locate the damper control, which is typically found inside the firebox. This may be a lever, a handle, or a chain that you can pull or push to adjust the damper. If the damper is stuck, gently move it while ensuring the fireplace is cool and not in use. Always ensure the vent is fully open before starting a fire to ensure proper airflow and ventilation.