Should I open or close vent on gas fireplace?

Author: Avis Flatley  |  Last update: Saturday, April 5, 2025

One caution, though: Fireplaces with installed gas logs are required to have the damper open at all times. That's either because a pilot light is constantly burning under the logs or because the homeowner might forget to open the damper when he or she turns on the fire.

Is it OK to close the flue on a gas fireplace?

Closing the flue on a gas appliance would be extremely dangerous. If it burns it will create CO and CO2 that will poison the air in the building.

What is the proper venting for a gas fireplace?

Venting horizontally—through a wall—is a simple solution, ideal in cases where a gas fireplace is being installed on an exterior wall. Venting can be as easy as running pipe from the back of the fireplace out through the wall, then installing a termination cap.

What happens if you forget to open the flue on a gas fireplace?

The damper should always be open when a fire is burning in the fireplace. If a fire is lit and the damper is closed, the gas and debris have nowhere to go but into the house, causing a smoky situation.

Do you get more heat with a damper open or closed?

Yes, if you close your damper you will get more heat build up. Enough to possibly burn your house down or spill smoke and carbon monoxide into the home. Don't do it! Your fireplace was tested and listed with the damper wide open.

Should the damper be open or closed on a gas fireplace?

Should gas fireplace damper be open or closed?

Those gases contain carbon monoxide. Therefore, while it's great to save energy by closing off the damper inside a fireplace, be sure to do so in a safe manner. Do not close a fireplace damper until the fire is completely out.

How to get more heat from a gas fireplace?

There are several ways to increase heat output from your gas fireplace. Some methods include using a fireplace blower to circulate the air, installing a heat exchanger, placing a fireback behind the fireplace to reflect heat, and converting a gas fireplace to a gas insert.

Should the damper be fully open?

A closed damper also stops cold drafts from coming down the chimney. When you are using your fireplace, it needs to be open so that smoke can vent outside. It also allows fresh air to come in to feed the fire.

Can you run a gas fireplace without the flue open?

You need to leave your chimney's damper partially open to vent the carbon monoxide that the gas fire produces, so much of the heat generated by a vented gas log set goes up the chimney.

What is the difference between a flue and a damper?

The damper and flue are two different parts, but they are related and involved in the same function. The flue is the inside tunnel of your chimney that brings gases from your fireplace out of your home, while the damper closes or opens the access to the flue.

How do I know if my gas fireplace is properly vented?

Look for Vent Pipes

These pipes facilitate the safe release of combustion byproducts, such as carbon monoxide and moisture, outside the home. By efficiently venting these gases, vent pipes help ensure indoor air quality and reduce the risk of potential health hazards.

Why does my gas fireplace smell like burning plastic?

It is normal for your gas fireplace to smell like burning plastic after being newly installed. The smell comes from the ingredients used in manufacturing and can emit a slight odor at first but should wear off in a couple hours.

When should you close the vent on a fireplace?

If the flue is left open after the fire goes out, all the heat generated will escape. Closing the flue will keep the heat inside; you must be careful not to close it too quickly, otherwise you may trap smoke and carbon monoxide in your home. It's best to keep the flue closed when the fireplace is not in use.

Why does my gas fireplace not heat the room?

While your fireplace is in use, the damper should be fully open, otherwise the restricted airflow can reduce the heat and intensity of your fires. ✓ Poor or improper fuel. The type or quality of fuel used in the fireplace will have a direct impact on its heat output.

Should fireplace flue be fully open?

But can I close my damper just a little so I lose less heat on my chimney? No, never do this. The damper to your fireplace must be completely open when a fire is burning. If you close the damper even slightly, you risk allowing smoke and other dangerous contaminants from the combustion process into the house.

Why does my gas fireplace have a flue?

A flue is necessary to effectively and safely remove harmful gases – such as carbon monoxide – which are created when the gas fuel is burnt. They are safely transported into the air outside the home.

Should I close the flue on my gas fireplace?

The answer is yes in most cases – we recommend closing your damper when your fireplace is not in use. The only instance where you should keep your fireplace open is if you have a set of gas logs. In this case, keeping your damper open prevents carbon monoxide poisoning.

Do you need to open a window when using a gas fireplace?

Yes. Burning logs produces carbon dioxide as well as carbon monoxide, so the open vent is needed to get these harmful gases out of the house.

How long to leave the flue open after a gas fire?

Leave the damper open overnight. Yes, you will lose some heat up the flue, but you will save the occupants of the home from poisoning by colorless, odorless carbon monoxide. In the morning, stir the embers and check them for any hot spots.

How far to open a damper on a gas fireplace?

wood or gas . . . . always fully open the damper. If you're burning wood, keep it fully open until all the burning embers are completely burned out. If it's a gas log set, turn off the flames before the closing the damper as far as possible.

What position should my damper be in?

HVAC Damper Open Or Closed In Summer/Winter

In most homes, dampers going to the upstairs are open in the summer and closed in the winter. By closing the dampers to the upstairs in the winter, it allows for the heat to rise naturally after first being introduced into the lower levels of the home.

Should vent damper be open or closed?

In most houses, dampers on the upper level are opened in the summer and shut in the winter. In the winter, closing the dampers on your HVAC system to the upstairs allows for heat to rise naturally as it is distributed throughout the home.

Why is my gas fire not giving out much heat?

The most likely explanation here is that not enough fuel is being burnt quickly enough to generate the heat output capabilities. When lighting the fire it is important to get the appliance very hot and to establish a glowing fuel bed before adding new fuel. This enables new fuel to start burning straight away.

Why is my gas fireplace so cold?

If you have a direct vent gas fireplace, check to see if the glass is getting cold while it is not running. Normally, the pilot light should stay lit to prevent this. If the glass is cool & cold air is coming from the bottom of the fireplace, then you may have a poor insulation or negative pressure issue.

How to make a gas fireplace more effective?

How to Optimize:
  1. Clean the Vents: Over time, vents and chimneys can accumulate dust, soot, and debris. ...
  2. Check for Blockages: Ensure that nothing is obstructing the vent or exhaust pipe. ...
  3. Install an Air Circulation Fan: Many modern gas fireplaces offer optional fans that circulate warm air more effectively.

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