How to Stop Downdraft in a Wood Stove (DIY Guide)

An unwanted downdraft can fill the room with dangerous smoke from the wood stove. Uneven pressure in the chimney can create downdrafts, but how do you stop them? Learning how to manage your wood stove and keep soot, creosote, and smoke out of your home can make a huge difference.

To stop a downdraft in a wood stove, follow this process:

• Open the windows
• Seal the stove’s door
• Insulate the wood stove
• Remove soot buildup
• Adjust the damper
• Turn off nearby fans
• Get a longer chimney flue
• Shut exhaust vents
• Repair chimney cracks
• Test for a downdraft

Throughout this article, we’ll show you the step-by-step method to diagnose a downdraft and stop it in its tracks. Downdrafts are quite annoying and potentially harmful, but we have you covered with preventative tips and quick repairs.

Open Nearby Windows

Downdrafts are created by pressure and temperature fluctuations. If your wood stove keeps spewing smoke and soot, it’s time to equalize the pressure. Since windows are wide and offer excellent pressure regulation, opening one or two nearby frames can make a massive improvement.

So, why should you open a window to stop a downdraft?

• Propping open a window lets the cold air escape rather than building up inside of the house. When the pressure builds, it forms a vacuum. As soon as you open the wood stove, the vacuum pulls the smoke into your home. Opening a window stops the vacuum’s suction and equalizes the pressure.
• Opening a nearby window lets the fire heat up quicker, sending the smoke upward. Soot, creosote, and heavy smoke downdraft when there’s not enough warmth to propel them through the chimney. Your windows push the cold inside air outside. The flame will heat up quickly and eliminate the excessive amounts of soot.

Note: For this trick to work, it’s important to open the closest window to the wood stove. The nearby pressure differential makes the most noticeable difference. Consider creating a cross breeze by opening two windows across from each other to alter the pressure.

Check and Repair the Wood Stove’s Seals

Wood stoves have a few sealed areas that regulate the downdraft. When the pressure is sealed, it forces the smoke up and out of the chimney. However, small cracks and unsealed doors can wreak havoc on the wood stove. The last thing you want is a downdraft caused by tiny cracks that quickly grow.

Here are the three most common places where seals break:

1. Inspect the door’s seal. This gasket keeps the warm air from escaping around the door’s edges. Not only does it prevent downdrafts, but it also helps increase the interior heat. As we mentioned above, quicker heating means less creosote and soot. This seal is specific to your wood stove, so it’s best to consult the manufacturer.
2. The firebrick needs to be sealed and snug. The seal is broken if the firebrick is cracked, too small, or misaligned. Adjust or replace your firebrick if any of those three damages apply. Much like the door’s gasket, it’s best to choose a firebrick that’s the correct dimensions recommended by the company.
3. Ensure the baffle plate is secured. The baffle plate is above the stove in a small compartment. You can access it within or above the stove (if your model has one). These plates and blankets can shift or crack from wear and tear. Replace damaged baffle plates to tighten the seal.

Insulate the Wood Stove

Insulating a wood stove can promote an updraft, reducing the smoke and other contaminants from falling into your house. Paired with proper seals, additional insulation works wonders. The two best forms of insulation for a wood stove include baffle blankets and firebricks.

Using a Baffle Blanket

The Lynn Manufacturing Universal Baffle Blanket measures 20 x 24 x ½ inches, making it ideal for most wood stoves. You can cut it to the proper size of your stove’s interior dimensions. Unlike plates and bricks, this baffle blanket can’t crack or break. Proper installation seals and insulates the wood stove, promoting an optimal updraft.

Consider Firebrick

Firebrick isn’t found in all wood stoves, but it’s long been a popular choice. Adding firebrick to the bottom, sides, and top of your stove will drastically reduce the escaping heat. Instead of taking a long time to heat up, the fire will warm up in a matter of minutes. The result is a reduced chance of dealing with nasty downdrafts.

Remove Soot and Creosote

It’s important to remove soot and creosote to unclog your wood stove. A clogged chimney alters the pressure and sends some of the smoke back downward. You’d have to deal with downdrafts even if you opened the window and chimney damper. Fortunately, eHow explains you can scrub most soot and creosote with a stiff bristle brush.

Here’s a quick guide to eliminating thick soot from your wood stove:

1. Mix a few drops of dish soap with warm water.
2. Use a pumice stone, stiff brush, or abrasive sponge to scrub the soot with the mixture.
3. Repeat the previous step until the soot and creosote are gone.
4. Scrub the wood stove and chimney with a wet newspaper to remove deep-set soot.

If you prefer a hands-free cleaning, you could hire a professional. Another option is using the Co-Mate Chimney Cleaner. Sprinkle a little bit of this powdered solution on the wood before you light the fire. The cleaning mixture slowly strips creosote and soot as it burns. It also prevents long-term buildup.

Soot, creosote, and mold can create foul smells leaking from the wood stove. It’s important to remove them with manual cleaning, creosote solutions, or professional inspections for health and safety purposes. We recommend using the aforementioned solution, then cleaning it with a sponge or an expert right before and after the colder months.

Adjust the Chimney Damper

Chimney dampers are small levers that open and close to regulate the smoke. If it’s too far open, it can invite cold air into the wood stove. If it’s too far closed, it’ll create a downdraft. This pressure change sends the smoke into the stove, causing it to permeate the room. Minor adjustments go a long way for chimney dampers.

According to Priddy Clean, old chimney dampers can warp and change the draft. If your chimney damper won’t open or it’s clogged with soot and creosote, it’s time to contact an expert cleaning crew. The damper plays a crucial, irreplaceable role in preventing foul odors, downdrafts, and clogs.

To adjust the damper, locate the damper lever inside of the wood stove’s door. It’s best to use pliers or gloves since the damper lever can be quite hot from the fire.

For an in-depth video guide, review this helpful tutorial:

Turn Off as Many Fans as Possible

Anything that alters your home’s pressure will influence the wood stove’s flue. Floor fans, ceiling fans, laptop fans, and anything in between can cause a downdraft. After opening a nearby window, you should turn off any fan in the same room as the wood stove. This process ensures all of the pressure goes upward through the chimney.

However, some people prefer using fans to blow cold air out of the window. If you insist on using a fan, point it toward an open window. This setup pushes the cold air out while letting the warm air rise to the ceiling. For this reason, you can’t use ceiling fans while running the wood stove. High ceilings make them a little less effective, so it could work if you have a vaulted roof.

Note: Never point a fan at a wood stove. Some people attempt this because they want to push the air through the chimney, but it lower’s the fire’s temperature. A reduced flame temperature creates more soot and heavy smoke, leading to more downdrafts.

Extend the Chimney’s Flue

The Fireplace Technician mentions the importance and effectiveness of extending a flue by three feet. A chimney flue guides the smoke and soot through the roof, expelling it at the top. If the flue is too short, the temperature will cool off and drop the heavy smoke as a downdraft. You’ll need to hire a professional to extend the flue, though.

So, why does lengthening a chimney flue reduce the chances of a downdraft?

• Natural obstructions can get in the way of the pressure, sending it downward. Large trees block the flue and the top of the chimney. If you can extend the flue beyond the trees, you won’t have to worry about a downdraft or drastic pressure change.
• A short chimney flue gets clogged much quicker; Thus, increasing the flue’s length reduces the soot and creosote buildup. You’ll have longer times between mandatory cleaning sessions, reduced odors, and a much smaller chance of downdrafts.
• A longer flue increases the upward pressure because it has more suction. The longer the suction through the chimney, the better the pressure will be for the updraft. A three-foot increase is often more than enough to achieve these three benefits.

Close the Exhaust Vents

Do you have exhaust vents in nearby bathrooms, kitchens, and similar locations? These vents immediately change the home’s pressure. Closing all nearby exhaust vents allows the pressure to funnel through the chimney rather than going toward the vents. In fact, these exhaust vents might be pulling smoke from the wood stove, sending it throughout the house.

Kitchen exhaust vents are exceptionally strong because they’re designed to remove smoke and odors. If you keep the vent fan on, you’ll have serious downdraft issues. However, the fan can be off while still creating problems. The vent’s opening is enough to alter the wood stove’s performance.

If you want to use an exhaust fan while the wood stove isn’t in use, we suggest shutting the stove’s damper. The damper can invite cold air into the room. Closing the door and damper will prevent the vents and fans from pulling soot and ash into the house. Don’t forget to open the damper every time you use the wood stove to prevent clogs and downdrafts.

Repair the Chimney’s Cracks

Chimney cracks can grow and become expensive repairs. It’s essential to fix the cracks and damaged portions as soon as you can. These cracks let cold air into the wood stove, which creates a downdraft. The fire can’t get hot enough to push the pressure upward, so soot and creosote form inside of the chimney.

You should also repair the chimney for these reasons:

• Chimney cracks harbor moisture, which leads to soot, mildew, and mold buildup. All of these contaminants are dangerous, smelly, and create a downdraft. Not only that, but they can worsen the cracks and make them much more susceptible to nearby structural damage.
• A cracked chimney ruins the seals formed by the wood stove’s door, baffle plates, and firebrick. These three components are crucial, but their seals are useless if there’s a chimney crack. The pressure’s direction is instantly changed because of the external temperature and airflow coming through the damaged section.

Test for a Downdraft Regularly

Downdrafts are quite easy to test for without flooding your house with soot and smoke. Follow this helpful process:

1. Ensure the wood stove is off, and the damper is open.
2. Place a lighter in front of the vents near the bottom of the wood stove’s door, ensuring the door is closed.
3. Light the lighter to see if the flame blows toward the house or goes into the wood stove.
4. If the fire blows backward or is extinguished, there’s a downdraft; If it blows forward or stays still, there’s no downdraft.
5. To reverse the downdraft, light a newspaper inside of the wood stove to warm the chimney’s flue and make it easier for the flame to go upwards.

Remember, a hot wood stove directs the flame up, while a cold wood stove lowers the pressure and increases the chances of a downdraft.

Here’s a quick video guide to test for downdrafts in your wood stove:
https://www.youtube.com/watch?v=zn5g6D9hMWM

Steve Rajeckas

Steve Rajeckas is an HVAC hobbyist with an avid interest in learning innovative ways to keep rooms, buildings, and everything else at the optimal temperature. When he’s not working on new posts for Temperature Master, he can be found reading books or exploring the outdoors.