Fireplace Damper Secrets – When to Close it?

What’s the purpose of a fireplace damper? Should it be open, closed, or partly open when I build a fire? What do I do if it’s an older fireplace and the damper doesn’t operate correctly?  For these answers and more, keep reading.


Chimney Sweep Masonry Diagram from Ash Away

A damper is a small mechanism built into your fireplace and designed to seal up the chimney when the fireplace is not being used.  The chimney damper prevents warm, interior air from drafting up the chimney and keeps cold air from entering.  Think of the damper as a mini door that separates the firebox from the chimney when closed.

When building a fire in the fireplace, make sure to open the damper; otherwise, smoke will back up quickly and fill the room—guaranteed! So, you always want to check to ensure the damper is entirely in the open position when building a new fire.


Fireplace Damper - Open or Closed?

The best way to check for an open damper is to look inside at the top of the firebox. Do this before you get a fire going, of course! If it's open, you should be able to see up the chimney. If the chimney is offset, you might not see all the way up it, but you'll be able to see at least partway. If the damper is closed, it should be obvious because the chimney's inside will not be visible.

Some dampers are made of cast iron and operate on a worm gear mechanism. Others pivot open and close by moving a lever. Yet others might slide on a rod or bar. Regardless of their mechanism, make sure the damper is fully open before getting a fire going.


A fireplace damper should always be kept open while the fire is burning.  Furthermore, the damper should be kept open until all the embers are completely out since smoke and dangerous carbon monoxide can enter the house.

Once the ember bed is entirely out, close the damper. You may want to wear heavy leather gloves since the damper could still be quite hot. It will be dirty from soot.   With this procedure, warm air from your living room is not lost up the chimney.

Every year, WE LOVE FIRE experts get phone calls like this: "Why does my living room cool off so fast, and the furnace seems to run more when I get a fire going?"  "Shouldn't my house stay warmer after a fire?"  "My family room feels drafty." Odds are, the answer to these questions is that the fire has gone out, and the damper was left open, allowing cold air into the room.

By leaving the damper open, heat is lost. Essentially, warm air is pulled through a large hole in your living room ceiling. It's called a chimney!



Some, but not all, zero-clearance factory-built fireplaces have dampers.  All masonry fireplaces should have a damper.

Generally speaking, if your fireplace is designed with gasketed ceramic glass doors, it will not have a damper.  EPA-certified fireplaces and stoves are designed to be burned with the doors closed tight.  EPA-certified fireplaces have primary air controls that allow a specific air volume into the firebox for efficient combustion.  In essence, the chimney is always “open” and cannot be closed off with a damper.

However, the sealed, gasketed doors prevent air leakage and smoke from entering the room.

The primary air control controls the burn rate.  More air to the fire means more heat in the room and a shorter burn time.  Reducing the amount of combustion air results in longer burn times and less intense heat.

If you own an older stove or fireplace, perhaps one with bi-fold doors, there should be a damper that can be opened and closed.  These are not sealed-up or gasketed units.  The air control over the burn rate is usually not too precise.  And, efficiencies for this type of equipment are not rated but are very low compared to an EPA-certified model.



Do not confuse the primary air control with a damper.  There are separate and distinct functions for both.

The primary air control manages the burn rate.  It determines how hot or lively the fire is and how much heat is produced.

On the other hand, the damper opens and closes the chimney flue to create the necessary draft, pulling smoke up and out of the firebox.



Dampers installed in wood stove connector pipes are old, outdated technology.  They are not recommended with today's equipment.  Manufacturers design stoves that are easy to operate.  Today, we control the amount of air into the stove, not the amount going out, by placing a restriction or damper in the connector pipe!

Available from some online sites, heat reclaimers are designed to pull heat out from a wood stove's black connector pipe.  Most hearth dealers advise against using these devices.  They can lead to creosote quickly forming in the chimney because significant heat is removed from the connector pipe.



If the original damper for your fireplace is missing or beyond repair, your WE LOVE FIRE expert will likely recommend a lock-top sealing damper.   This type of damper is a spring-loaded cap installed on the top of the chimney. A cable is installed into the firebox. A cable installed in the firebox springs the cap to open or close the chimney. These are pretty effective at thoroughly sealing up the flue and preventing the loss of warm air when the fireplace is not in use. If yours needs replacing, a professional should probably evaluate this project.

Remember that your WE LOVE FIRE dealer is a terrific resource, and we’re here to help in any way we can.

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..

1 Response

  1. Tips to Keep Your Home Energy Efficient This Winter
    […] fireplace damper is a mechanism that keeps your fireplace sealed when not in use. Keeping your damper open during […]
  2. Amy Saunders
    OMG! I never realize that closing our chimney damper can help maintain the warmth of our indoor space as well. As winter approaches, I plan to spend more time just relaxing in front of my fireplace. I'll keep this tip in mind so I'll be as comfortable as possible.
  3. How to burn less firewood and reduce emissions - Going green time
    […] flue damper should be kept open when the fire is burning. This helps the fire burn hot, reduces emissions and […]

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