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When Should You Close the Damper on a Fireplace?

You should close the damper on your fireplace once the fire and embers have all burned out. This prevents warm air in your house from escaping out the chimney. You should open the damper before lighting a fire and close it once the fire is done burning. 

Why is the damper so important? Read on to learn more about this feature of your wood-burning fireplace. 

Why Do Fireplaces Need a Damper?

The damper on a fireplace is a small door that blocks air from flowing up and out the chimney. Chimneys are designed to suck up hot air and pull unwanted smoke and gases from the fire out of your house. The damper blocks any airflow when the fireplace is not in use. It can also regulate airflow while burning wood for a cleaner and more efficient fire. Let’s look deeper into each of these uses. 

Dampers Block Airflow When Fireplace Is Not in Use

The damper should be open when you have a fire going to allow the smoke and carbon monoxide to flow up the chimney and out of your living space. If you start a fire with the damper closed, you will fill your home with smoke! It is important to keep the damper closed when no fire is burning, especially when the weather is cold, because the chimney will pull that warm air out of the house. This may cause your furnace to work harder to keep up, costing you even more money on your energy bill. 

Another good reason to keep the damper shut is to prevent downdrafts. This happens when strong, cold wind pushes air down the chimney. An open damper will let all that cold air inside and cause major drafts. Keep in mind that downdrafts can be caused by improper chimney height or construction. If you find downdrafts to be a regular occurrence in your fireplace, you should contact a chimney professional for an inspection. 

Dampers Regulate Airflow When Burning a Fire

Some older fireplaces have a very large opening inside the throat of the chimney. This creates a lot of airflow. While this can be useful when starting a fire, too much airflow will cause most of the fire’s heat to be sucked up the chimney. In order to keep more heat inside the home, the damper can be adjusted to reduce the size of the opening. Restricting airflow will also cause the wood to burn more slowly and last longer. 

Do All Fireplaces Have a Damper?

Not all wood-burning fireplaces have a damper. The two main reasons for this are age and design. Open fireplaces in older homes may not have a damper because the original builder decided it wasn’t necessary. Fireplaces were often a house’s main source of heat in the winter. People weren’t worried about a drafty fireplace because there was always a fire burning. Alternatively, the design of modern wood-burning cast iron stoves makes it where a damper is not needed. The stove’s flue is already the perfect size to regulate airflow during a fire, and the front door panel stays closed, preventing any drafts when the unit is not in use. 

When Should You Close the Damper on a Fireplace?

Your damper should be closed at all times when a fire is not burning. This will prevent any temperature-controlled warm or cool air from escaping up the chimney and out of the house. Close the damper on your fireplace when you are done using it and when the fire has gone cold. 

Make sure that the embers are completely dead before closing the damper. Stir the ashes to see if anything is still glowing. Glowing embers are a sign that combustion is still occurring. Closing the damper too soon may cause dangerous chemicals like carbon monoxide to leak into your home. If you need to go to bed before the embers have cooled, you may close the damper partially to reduce the chance for overnight drafts while still letting the smoke and carbon monoxide out of your living space. 

Before (or during) heavy rain and winds, check your fireplace damper to make sure it is closed. If the damper is left open in these conditions, any rain or debris that makes it past the chimney cap will end up in the fireplace. It’s not enough to flood your home, but the moisture can make lighting your next fire a little difficult. This weather is when those pesky downdrafts are likely to occur. 

Should the Fireplace Damper Be Open in the Summer?

You may think that since the damper lets out warm air in the winter, it would do the same in the summer to keep your house cool. This is not the case. The damper does not discriminate between warm and cold air. The chimney will suck up whatever air is in the house—warm or cold—and release it outside. It has the effect of an open window. 

You should keep your damper closed in the summer, especially if you have a central air conditioning system. Keeping the damper closed in the summer will keep your cool air inside the house. It’s the same principle as keeping your windows closed while the A/C is running. Keeping that cold air inside puts less strain on your HVAC system and lets it run more efficiently. 

How Do You Know if Your Damper Is Open or Closed?

All this talk about dampers being open or closed—but how do you actually know if it’s shut or not? Thankfully, it is easy to check your damper to see if it is open or closed. Here are three surefire ways to check your fireplace damper to make sure it is in the correct position. 

Check for a draft. Do you get a chill when you walk past your fireplace? This may be a sign that your damper is open. Reach your hand into the empty fireplace. If you feel a breeze, your damper is open. No airflow means the damper is closed. 

Look in the firebox. Stick your head in the fireplace and look up. Remember to only do this when there is no fire. Can you see up the chimney? If so, the damper is open. Keep in mind that sometimes the flue is offset from the fireplace throat, which would obscure part of the chimney from your vision. In this situation, you will still see part of the chimney if the damper is open. You will not be able to see up the chimney at all when the damper is closed. 

This technique doesn’t work if your damper is located at the top of the chimney. In this case, you’ll have to check the position of the damper’s controls. 

Check the controls. This is the best way to know the position of your fireplace damper. There are multiple different mechanisms used to open and close the damper, depending on your fireplace model. It could be a metal handle or lever. Top-mounted dampers are controlled with a pull chain that hangs down the chimney. Here are the three most common damper controls and how to use them: 

  • A poker control with a ratchet arm will open the damper as you push it in and close the damper as you pull it back towards you. 
  • A rotary control works similarly, where pushing it in by rotating the handle will open the damper and vice versa. 
  • A chain control is used for a top-mounted damper. The damper is open when the chain hangs loose in the firebox. Close the damper by pulling the chain down and securing it in the bracket mounted to the side wall of the firebox. 

Some controls are more difficult to read than others. If you’re not sure which position means open and which means closed, set the controls in one direction and then look up the firebox to check the damper’s position. Then, set the controls in the other direction and check again. When in doubt, a fireplace service professional will be able to inspect your unit and give you a definitive answer.