When Should The Fireplace Damper Be Closed?

If you burn wood in a fireplace, you know the damper should be open before you get a fire going.  But is halfway open good enough?  Less heat will be lost up the chimney, right?  Can the damper be closed as the coals are dying down?  You’ll retain a bit more heat, right?  Let’s discuss an important part of your fireplace; the damper.


A damper in a fireplace is located at the top of the firebox.  The primary purpose of a damper is to seal off the firebox from the chimney.  Why is this so important?  We know that cold air is heavier than warm air.  With the damper left open and no fire in the fireplace, cold air can quickly spill down the chimney and into the room.  But, depending on the air pressure and air flow in your house, sealing off the fireplace will prevent warm air in your home from being pulled, or lost up the chimney, too.  One way or another, you have paid to heat the warm air in your home.  So, let’s not lose it by leaving the damper open when there is no fire in the fireplace.


If you have a masonry fireplace, odds are high the damper will be one of two types.  The first is a piece of cast iron that spans the width at the top of the firebox.  These are often open and closed with a worm gear mechanism.  There is normally a key that will be seen from the front of the fireplace.  By turning this key all the way to the left, the damper will open.  Conversely, turning the key clockwise to the right, the damper is closed.

The second type of damper is operated by a lever, normally mounted on the right inside wall of the fireplace.   By pulling the lever toward you, the damper is open.  By pushing it away from you, the damper is closed.

On some zero clearance, factory built fireplaces, the damper is a little different than the two mentioned above.  The damper in many ZC fireplaces is a simple metal plate that pivots open and pivots closed when a lever is pushed or pulled.  Note that most EPA certified ZC fireplaces do not have a damper.  Gasketed, sealed doors keep cold air from infiltrating.


The damper should be kept closed when there is no fire or coals burning.  Warm air from your home will not be lost up the chimney when the fireplace is not being used.

Fully open the damper before your start a fire and keep it fully open until all embers and coals have burned out.  This is to allow smoke and other combustion by-products to safely exit the fireplace, up the chimney.


An effective damper can be compared to your front door.  Left open and you’ll lose lots of heat from the house.  (Do some of those long “good-byes” with the front door wide open come to mind?)  Simply close the damper (or door) tight, and the heat is contained in the house.

But, what do I do with my older home’s fireplace that has a missing or badly damaged damper?   Years and years of heating up to high temperatures and cooling down can take a toll on any damper.  They can warp, twist or rust and begin to deteriorate.  A device called a “lock-top sealing damper” is the answer.  The cap on the top of the chimney is replaced with a spring loaded damper, or lid so to speak.  The chimney is effectively sealed at its top, not in the fireplace.  These lock-top sealing dampers come in different sizes and shapes, but their function is the same as other dampers.  They seal up the fireplace.  They are designed to stop the cold outside air from coming down the chimney or losing the warm, heated air from the house, up the chimney.

How does a lock-top damper work?  A heavy duty cable is installed down the chimney, through or around the old damper.  The cable is mounted to a handle and bolted to the inside wall of the fireplace.  The cable is pulled to spring the damper up, or to open it.  Or, it can be pushed to seal it back up.  The installation of this device is best left to a professional.


Gas logs in fireplaces are very popular.  Does the damper need to be open when they are being used?  This is a common question and the answer is a resounding “yes”!  In fact, a clamp is required to be installed on the damper to prevent it from closing tight even when the logs are not turned on.  Since the pilot light runs continuously and there’s a risk of forgetting to open the damper before the gas logs are lit, the damper must be kept slightly ajar by installing a small C-clamp.


Before you start a fire, any type of fire . . . . 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.

If there is no fire, always keep the damper closed to prevent air infiltration and heat from being lost up the chimney.

Using a damper is a simple concept.  Not using it correctly or forgetting about it all together can have serious consequences that can put your loved ones and property at risk.

Below is a list of fireplace and grill stores that service Virginia (VA)

Manassas, VA

Winston's Chimney Service
11301 Industrial Road
Manassas, VA 20109

Winston's Chimney Service LogoVisit Store Page

Mechanicsville, VA

Hearth & Home Shoppe
8151 Mechanicsville Tpk
Mechanicsville, VA 23111

Hearth & Home Shoppe LogoVisit Store Page

Roanoke, VA

Dixie Building Products Inc.
3342 Melrose Ave NW
Roanoke, VA 24017

Warrenton, VA

Costello's Warrenton Fireplace & Hot Tub
251 West Lee Hwy
Warrenton, VA 20186

For more information, contact your local fireplace and grill store..

12 Responses

  1. PAT
    I have a fireplace that at one time was an electric one we decided to take it out however and doing so we have no damper it is just an open pit oval shaped fireplace and my husband feels we don't need to have a damper. I was always under the assumption you needed to have one for safety reasons and so that you would not have the loss of heat or cold air coming in. And for safety reasons please help with this issue.
    • Dominique Page
      Good morning Pat! Thanks for reaching out. You are correct, a damper is useful to prevent cold air from coming down the chimney when the fireplace is not in use, or lowering the the heat loss going up the chimney. Either way, it prevents air movement. One solution might be the installation of a Chim-a-lator. We have a couple articles that you might find helpful. Fireplace & Chimney Maintenance & Fireplaces & Wind If we have a local We Love Fire Partner, they will be able to help you with the best solution for your home. Dominique
  2. How fireplaces work ? - We Love Fire
    […] a wood-burning fireplace is not particularly difficult. Make sure the damper is fully open. Using dry kindling and a few wads of newspapers, get small pieces of wood actively […]
  3. Karen
    Hi we have a masonry wood burning stove which we use to heat our home in the winter - primary heat source. We use birch and tamarack wood, seasoned and well dried. I open the damper all the way when starting the fire. Once it is burning well and I have good flames I began the process of closing down the damper. I close it about half way and let it burn for about 10 minutes, then I close it so that it is open about 1/4. Then after a few minutes I damp it right down so that my fire burns longer. I close the damper off when we leave the house and during the night but I always make sure the fire is burning well before I do this. I find it confusing when you read always leave the damper fully open while burning - you would sure go through your wood fast and all your heat is going up the chimney. Hopefully I am doing this right?
    • Dominique Page
      Hi Karen, thanks for your comment. The advice to always leave the damper open while burning wood applies to 'open fireplaces', not to stoves like yours. An open fireplace, if the damper is closed, would send all of its smoke back into the house. In your case, for a stove, the door is sealed and the damper controls the airflow and allows to burn slower.
  4. Peggy Dotson
    Our fireplace will night light it downdraft every time we try to start it we clean the chummy out we just don't know what to do it lit fine last yr
    • Dominique Page
      Hi Peggy, thanks for reaching out. The best would be to get the fireplace expert take a look and see what has changed in your chimney. They will make it work for sure. All the best!
      • Anne
        I am preparing to sell my house. I have a fireplace with a gas log and a top-locking damper. Can a clamp be added so the top-locking damper is not totally closed? If so, how (I can't find anything online to explain how.)? If not, what do I need to do to be code compliant? I'm keeping my fingers crossed that there is a simple solution. Thanks for your help!
        • Joseph Bodden
          Anne: thank you for taking time to ask your question about top locking dampers. The clamps for gas logs are designed for the damper in the fireplace, not a top locking damper. Their purpose is to provide a margin of safety so the burned gas can vent to atmosphere in case a person forgets to fully open the damper. We would not endorse adding a clamp to a top sealing damper. The purpose of this type of damper is to seal the chimney and by installing a clamp on it, you're defeating its intended use. If you have a gas log set with a standing pilot light in your wood burning fireplace with a top locking damper, we would recommend you turn off the pilot light when not in use. Granted, this may be a bit inconvenient. Another option may be to upgrade the gas log set. Many newer models today have electronic ignition for the pilot light, so the pilot light is only on when the unit is operating. Your damper would still need to be open when using the log set. Hope this helps and good luck with the sale of your home! Joe
  5. Diane Freeman
    I have a fireplace which is no longer used. We put gas logs in and that is what we use now. In the winter there is a good bit of cold air coming in under and around the gas logs. Please advise how you alleviate this problem. We had considered sealing the top of chimney up, but in reading information this isn’t recommended. What can I do to stop the cold air from coming in. Thank you Diane
    • Joseph Bodden
      Diane, thank you for your time checking out WeLoveFire.com and for your question. Unfortunately, with a gas log set there is not a lot you can do to alleviate the cold air spilling down your chimney, especially a chimney that is on an exterior wall of the house. During the gas log installation, it's very likely that a damper clamp was installed to prevent the damper from being closed all the way. This is safety requirement from gas log manufacturers. The reason for this is if the gas logs are turned on and someone forgets to open the damper, the harmful by-products of combustion will be vented up and out the chimney. The downside of course, is that the damper is always open an inch or two and is never sealed tight. You might consider a gas insert to replace the gas log set. There are several advantages: Inserts operate in the 75% - 80% efficiency range. Gas logs are not rated. In fact, some take more heat from the house than what they contribute to it. Most gas inserts will use between 20,000 and 40,000 BTU's of gas per hour, most gas logs 50,000 to 80,000 BTU's per hour. Inserts use half as much gas with high efficiency's and supply significant heat to your home from the gas that's burned. In other words, more heat from less gas! A gas insert will also solve your cold air problem. Inserts utilize two, 3" flexible aluminum vent pipes that are installed up the chimney. One brings combustion air into the insert, the other vents the combustion by-products, out. As these two pipes are passing through the damper, the damper is permanently disabled or removed. This space is sealed up with a ceramic fiber insulation to prevent cold air from spilling down the chimney. More expensive; yes. Will it add more comfort and value to your home; definitely. An insert is a permanent solution to your cold air issue.
  6. MistyJ
    "The damper in many ZC fireplaces is a simple metal plate that pivots open and pivots closed when a lever is pushed or pulled". We have a Travis Industries ZC Fireplace --can't find a model number on anything. There is a metal lever on top of the unit that has about 8 slots in it. We put it in the middle. Seems like a silly question, but is it "push" to open? I would think being gas, we would never want to close it. Thanks for any info!
    • Joseph Bodden
      Misty: Thank you for taking the time to ask about your Travis Industries fireplace. Not knowing the specific model number, it's difficult to answer your question. But Travis products use a catalytic combustor in their wood burning fireplaces and we can tell you that pulled out, the bypass is open. To close the damper bypass and engage the combustor, push the metal rod in when the fireplace is hot, at approximately 500 degrees F. I'm not sure about your reference to gas. I do not believe Travis Industries wood burning fireplaces have any sort of gas option. There's a "GreenStart Ignitor" option on some units that use superheated air to assist when starting a fire. But, you should definitely check your owner's manual and either call your dealer or Travis Industries directly if you still have other questions. Sure hope this helps!

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