by Susan


by Susan


When to Close Fireplace Damper

Your fireplace damper must be open when you have a fire in your fireplace. It provides the necessary updraft for the smoke and prevents carbon monoxide poisoning. But when should you shut or close the wood-burning fireplace damper?

Not sure how to open or close fireplace damper? See damper instructions here.

Close Fireplace Damper In Warm Weather.

During the seasons you will not be burning wood in your fireplace, close the damper. An open damper is much like an open window or open door – interior air you are paying to air condition will be wasted and escape out any opening.

Open door and open damper - both let air conditioned air out

In the summer, an open fireplace damper is like an open door. Both let air conditioned air out of the home.

Close Fireplace Damper When Fire Is Completely Out.

During the part of the year you are using your wood-burning fireplace, open the damper before you light the fire. If necessary to keep the fire burning well and smoke-free, you may adjust the damper into a semi-open position.

Shut the damper when the fire is completely, absolutely out. That means ashes are cool to the touch even when stirred. If you close the damper before that, you risk carbon monoxide poisoning.

Functionally, this is what that means:

  • Start your fire before you “need” it.
  • Toward the end of the evening, let the fire die down instead of adding more logs.
  • Separate remaining bits of firewood on the grate. Stir embers on the fireplace floor.
  • 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. Only when they are completely cold to the touch is it safe to shut the fireplace damper.

Close the Fireplace Damper in Preparation for a Hurricane or Heavy Rains.

See Hurricane Fireplace Tips to see more about why you should close the fireplace damper with you are expecting heavy rains.

Is the Fireplace Damper Open or Closed?

To close a throat damper in a fireplace, lift the handle and pull it back towards you.

To remember whether your damper is open or closed (and to remember to close fireplace damper when the embers are completely cooled), you can use a brass damper hook with a Closed and Open side or a brass fireplace sign with a Closed and Open side.


 NOTE: For Fireplaces with Installed Gas Logs

If you have installed gas logs in your fireplace, the damper should never be closed.

  • If you have a pilot light constantly burning under your gas logs, shutting the damper puts you, your family and your pets at severe risk of carbon monoxide poisoning.
  • Even if your pilot light is not lit, there is the danger that someone might forget to open the damper when using the gas fireplace. Gas fireplaces emit a copious amount of carbon monoxide, so they must always have an open vent.

If your fireplace damper is stuck in either the closed or open position, here’s how to un-stick it.


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  1. Ron September 8, 2016 at 8:57 AM - Reply

    I feel like I should know this but I want to make sure
    since its been so long since I’ve used my very old (28yrs) gas fireplace i just wanted to be sure
    what the correct steps to lighting the fireplace are ?
    the fireplace is gas and has logs inside and a gas key to turn on the gas however it does not have a pilot or ignition system like my newer home fireplace does ( that pilot is on all the time and has an on off wall switch)
    thank you for your help

    • Tom January 7, 2017 at 7:58 PM - Reply

      Ron, one of that vintage should be check for safety by a certified gas appliance technician before it is used. He or she can give you instructions on the correct steps for lighting for the model you have. Enjoy your fireplace.

  2. voidisyinyang February 24, 2018 at 2:09 PM - Reply

    my sister leaves her chimney flue open all the time so she can smoke up the chimney. She ran out of heat twice now this winter. Now she claims she doesn’t have enough money for the heat! Leaving the flue open is the same as having money sucked out of the chimney! I told her she needs to remember to keep her flue closed. she said, “Yeah I should be better about that.” ?? What? Leaving it open is o.k. sometimes? haha.

  3. Jerry Fleming February 26, 2018 at 10:09 AM - Reply

    I have a gas log fireplace. Should I close the damper when the fire is burning in order to disseminate the heat into the room?

    • Tom June 2, 2018 at 7:43 PM - Reply

      Jerry, leave the damper open whenever the fire is burning so exhaust gases can escape through the chimney instead of entering your room.

  4. David November 9, 2019 at 12:31 PM - Reply

    I have a converted regular fire place with propane gas. It has a pilot light and was wondering if it is safe to close the flue with pilot light is on when not using the fireplace. Any suggestions would be helpful. Thank you

    • Tom January 5, 2023 at 12:13 AM - Reply

      We suggest using a gas fireplace damper clamp, David. It keeps the damper from closing all the way, so even gas from a pilot light can exhaust.

  5. Bonnie Gwaltney January 17, 2020 at 4:05 PM - Reply

    We know our natural gas fireplace flue should be entirely open when burning our gas logs. I was wondering when we are not running the log unit, but the pilot light is still ignited, can we leave the flue partially cracked so gases can escape rather than leaving the flue totally open to suck out our room heat? Thanks.

    • Tom January 5, 2023 at 12:10 AM - Reply

      Bonnie, if the gas fireplace has a lit pilot light, use a gas fireplace damper clamp. It attaches to the damper and allows it to close most but not all of the way closed, so even exhaust from the pilot light can escape up the flue.

  6. Steven Walter Loomis December 28, 2021 at 5:34 PM - Reply

    should you leave the damper slightly open on a gas fireplace when not using it. i.e. no fire and no pilot light in place?? just in case of a gas leak?

    • Tom January 5, 2023 at 12:07 AM - Reply

      If the gas is turned off to the pilot light (as you might during the warm seasons), there should be no gas leaking through the pilot light.

  7. Lucy November 22, 2022 at 2:18 PM - Reply

    After turning the gas off in my fireplace, when can the damoer be safely closed?

    • Tom December 31, 2022 at 3:55 PM - Reply

      If the gas fireplace has a lit pilot light, use a gas fireplace damper clamp and close the damper within minutes of turning off the gas fireplace. The damper clamp attaches to the damper and allows it to close most but not all of the way closed, so even exhaust from the pilot light can escape up the flue. If your pilot light is off, for example if you’ve turned off the gas to your fireplace for the warm weather seasons, you can close the damper entirely within minute of turning off the gas.

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