Is Your Fireplace Damper Open or Closed?

Knowing if your fireplace damper is properly closed and properly open is important. If you aren’t certain of the state of your damper, there are a few things you can do to find out.

What fireplace dampers do

Dampers are in place to control the flow of air between your home and your chimney flue and everything beyond it. In other words, inside air, and outside air.

When the fireplace is in use, the damper (whether it’s a throat damper just above the firebox or a top-mount damper at the top of the chimney) must be open. An open damper allows smoke to exit the chimney rather than backing up into the house. It also creates a draft of the air necessary for this to happen.

Dampers are made to close tightly when you aren’t using your fireplace in order to prevent air exchange between the inside and outside of your home. Closed dampers also keep small animals and insects that have accessed the flue from accessing your house.

Is your damper open or closed?

A flashlight should illuminate a throat damper well enough to see if it’s open or closed. For a damper at the top of the chimney, you’ll have a chain that controls the device. If you can pull on the chain before it jumps back up, the damper is open.

You can also start a small fire as a test. With a top-sealing damper, the smoke will have to move up the flue, so give it enough time to do that. If the smoke can’t get out, it will back up into the firebox. Simply use the chain to open the damper in this case.

If you have a throat damper that’s closed but you don’t know it, you will know it pretty quickly once a few clouds of smoke tries to get into the flue.

Another method is simply to feel the air. When either type of damper is closed, you should not feel any air when you place your hand up into the firebox.

It’s a good idea to commit to memory the handle positions of throat dampers and the chain operation of top-mount dampers to avoid confusion in the future.

Closed vs. completely closed

Often, a damper will basically close – that is, you can use the controls to manipulate it – but it won’t completely close. Unfortunately, a warped, rusted, or otherwise-damaged damper that leaves a gap in the seal isn’t something most homeowners will normally notice. Depending on the size of the gap, warm or cool air (depending on the season) from inside the house can slowly escape up the chimney. Likewise, the wrong temperature of air from outside can get into the house and make living uncomfortable.

Damper inspection

Annual fireplace and chimney inspections from a skilled service technician will include an examination of your throat or top-mount damper.

You want a damper that shuts completely and opens completely, and your inspector will quickly determine if yours does. Dampers sometimes can be repaired; often, the best solution is to replace the damper, especially if it’s getting up in years. If you’re having issues with your fireplace damper, the fireplace and chimney experts at Dubuque Fireplace & Patio of Dubuque, Iowa, are here to help. Give us a call at (563) 582-5156. If you live in the Highland, WI, region, call Chimney Specialists at (608) 929-4887.