How Long Can You Run a Gas Fireplace?

You can run a vented gas fireplace continuously.

Many gas fireplaces have an automatic timer that limits use to 2-4 hours. The fireplace will shut off, and you’ll have to relight it to continue to use it.

How Long Can You Run a Vented Gas Fireplace?

There is no time limit, though as mentioned, the unit might have an internal timer that shuts it off after several hours. 

While there’s no time limit because the combustion gasses are being vented out of the home, most manufacturers recommend turning off the fireplace overnight rather than running it while you sleep.

Whenever it is running, keep an eye on the fireplace to reduce the potential of an accidental fire or burns to small children or pets.

Vented vs Ventless Gas Fireplace

A direct vent gas fireplace or a fireplace with chimney exhausts all combustion byproducts to the outside including carbon monoxide.

Ventless gas fireplace units are considered safe because they burn the gas or propane very efficiently, so that there are minimal combustion byproducts. However, it is recommended that you have a window open for ventilation when running a vented gas fireplace and that you do not run it while you sleep.

How Long Can You Run a Ventless Gas Fireplace?

While generally safe, ventless fireplaces do have more potential to cause harm. Following these guidelines will help ensure safe use.

1 – Follow the manufacturer’s instructions included with the ventless gas fireplace. It should have clear directions for safe use and should answer the question – how long can you run a gas fireplace?

2 – Keep a window open at least a few inches near the ventless gas fireplace. This does two things. First, it allows the fireplace to use fresh air/oxygen from outside for combustion rather than using oxygen in the room.

All ventless fireplaces have an oxygen depletion sensor, or ODS. Its purpose is to monitor the oxygen level in the air, and if the unit is using up the room’s oxygen, the sensor will detect the low oxygen level and turn off the gas valve, effectively shutting down the unit.

Secondly, it allows for a steady supply of fresh air into the room to offset the potential threat from the combustion gasses.

3 – Don’t run the fireplace overnight or anytime you sleep.

4 – Shut off the unit and open a door or windows if you begin to feel drowsy for no apparent reason. Getting sleepy when you otherwise would not be tired is a potential sign of oxygen depletion or carbon monoxide poisoning.

5 – Keep the glass door on the front of the fireplace closed.

6 – If the fireplace vents with a chimney, keep the flue open for 30 minutes or so after the unit is turned off to make sure all dangerous combustion gases are exhausted.

Note: It’s not a good idea to run the fireplace for heat only – most are used mainly for ambiance.

Gas Fireplace Safety Measures

Before you start the fireplace, have a carbon monoxide detector with a fresh battery placed nearby. The detector should be on or near the floor because carbon monoxide is a heavy gas, and so it accumulates low in a room.

The first time you start a vent free or vented gas fireplace, open a couple of windows to allow for a cross breeze. A new fireplace will often give off odors when first lit as machine oil burns off the burner and internal parts.

Don’t pull chairs, a couch or anything combustible too near to the fireplace. Move items away even if you leave the lit fireplace unattended for a few minutes.

Can You Leave a Vented Gas Fireplace On Overnight?

Again, it is not recommended. In fact, to eliminate the possibility of doing this, most gas fireplaces will automatically turn off after 2-4 hours.

Can Leaving On a Gas Fireplace Cause a Fire?

Yes it can, so don’t leave your gas fireplace unattended.

Causes of fire include:

  • Faulty operation – the unit’s gas valve or line might be cracked or damaged allowing an excessive amount of gas to flow out of it.
  • Leaving combustible items like furniture or curtains too close to the fireplace.
  • Tipping over a portable gas fireplace – though all newer units have a tip-over switch meaning it will immediately shut off if it is tipped. 

Written by

Rene has worked 10 years in the HVAC field and now is the Senior Comfort Specialist for PICKHVAC. He holds an HVAC associate degree and EPA & R-410A Certifications. Protection Status