Chimney Downdraft! Causes, Signs, and How to Stop It?

Chimney downdraft is a serious problem that can create smoke in your home, turn off carbon monoxide detectors, and weaken your breathing. If you have a stove or fireplace in your home then it’s very natural that you can get Downdraft. So, as a homeowner, you should know every part, why get downdraft, how to stop downdraft in a chimney, how your chimney works, and how to clean your chimney. Otherwise, you’ll find your living room filled with smoke when the fireplace is lit. it’s a serious problem that can endanger the health of you and your family.

The downdraft in the chimney is a very bad experience. It can make your warm moment unbearable in an instant by spreading smoke all over the house. There are several ways you can protect yourself from this downdraft. Moreover, it affects the environment.

Downdrafts can cause your fireplace to smoke, your furnace to backdraft, and your stove to produce soot. In addition, downdrafts can also make it difficult to start a fire in your fireplace and can cause your furnace to work less efficiently.

Some things can cause downdrafts, including open windows, fans, and doors. If you think that you might have a downdraft problem, there are a few things that you can do to try to fix it.

One thing that you can do is to make sure that all of the doors and windows in your home are closed when you are not using your fireplace or stove. This will help to keep the air pressure in your home at a normal level.

Another thing that you can do is to use a fan to help circulate the air in your home. This will help to even out the air pressure and can help to reduce the amount of downdraft

How Does Chimney Work?

To know why a downdraft happens, you have to know about the operation of the chimney. The chimney is designed to depend on hot air rising to vent the smoke outside the home. The hot air from the wood-burning fire blows the smoke out of the chimney. This is because hot air isn’t as dense as cold air. As the hot air expands it rises in an attempt to equalize itself with the cool air outside your home.

Cool areas are low pressure and high pressure where warm air collects. If the low pressure is below hot air pressure, your chimney may have a downdraft. Energy-efficient new build houses can also change the airflow of the fireplace with more popular changes in air pressure.

Simply put, the principle of chimneys is that the hot air will rise above the cool air. The heat generated from the fire creates a pressure difference between the flue and the indoor air. This is the “Draft”, which pressurizes the air in the fireplace. The more intense the fire, the faster the wind rises and the chimney will work better. Moving the air out through the chimney ensures that the indoor air is warmer than the outside air.

If the chimney doesn’t work properly, there will not be enough drafts inside the flow and the result will be the opposite, there will be a downdraft. A chimney is required for any heat source to burn fuels such as wood, oil, gas, and coal.

Related: 4 Best Chimney Caps to Prevent Downdraft

What Is Chimney Downdraft?

Chimney downdraft is a condition that can occur when the outside temperature is colder than the inside temperature of the chimney. This time the smoke does not go out with the flue but returns to your living room or backdraft and fills the room with dark smoke.

This can happen if the fireplace is not being used and the flu is not open. Cold air can cause the chimney air to become heavier and begin to descend into the room below the chimney. This downdraft can also occur if there is a blockage in the chimney.

A chimney downdraft is caused by a difference in air pressure inside and outside the chimney. The pressure inside the chimney is usually greater than the pressure outside. This pressure difference can cause the air to flow out of the chimney and down into the room. The chimney downdraft can also be caused by a blockage in the chimney.

Causes of Chimney Downdraft

A downdraft in a chimney is caused by a difference in air pressure between the inside of the chimney and the outside air. The pressure inside the chimney is usually greater than the pressure outside, so the air inside the chimney wants to escape. This can cause a downdraft, which can cause the smoke from the fire to be pulled back into the room.

Several things can cause a downdraft in a chimney:

1. A cold front can cause a downdraft. When a cold front moves in, the air pressure outside decreases. This can cause the air pressure inside the chimney to be greater than the pressure outside, which can cause the air inside the chimney to escape.
2. A fire that is not burning hot enough can cause a downdraft. If the fire is not hot enough, the air inside the chimney will be cooler than the air outside. This can cause the air inside the chimney to escape, which can cause a downdraft.
3. A chimney that is too tall can cause a downdraft. If the chimney is too tall, the air inside the chimney will be cooler than the air outside. This can cause the air inside the chimney to escape, which can cause a downdraft.
4. A chimney that is not lined properly can cause a downdraft. If the chimney is not lined properly, the air inside the chimney can escape. This can cause a downdraft.
5. A blockage in the chimney can cause a downdraft. If there is a blockage in the chimney, the air inside the chimney will be forced out. This can cause a downdraft.

The Signs How to Tell if You Have Chimney Downdraft

If you have a wood-burning fireplace, it’s important to have your chimney checked regularly for signs of downdraft. Downdraft occurs when air flows down the chimney and into the room, rather than up and out. This can happen for many reasons, but the most common is a blockage in the chimney.

There are a few tell-tale signs that you may have downdraft in your chimney:

Smoke in the Room

This is the most obvious sign that there is something wrong with your chimney. If you notice smoke coming into the room, it’s likely due to downdraft.

Found Soot on the Glass

Another sign of downdraft is that it can send small spots on the glass through the air. These are dark black, the color will be very visible in the window. This means that if small spots are seen on the window, then the backdraft can be it.

Using Carbon Monoxide Alarm

This will require a carbon monoxide alarm. If your carbon monoxide alarm is triggering. Even if you do not see the immediate threat then it is a sign that this is happening in your home due to a downdraft.

Soot on the Walls

If you have soot on the walls near your fireplace, it’s another sign that downdraft is occurring.

Drafty Feeling

If you feel a draft near your fireplace, even when the fire is not lit, it’s another sign that downdraft is present.

Eye Irritation

If you are near a fireplace, it will irritate your eyes even when it is closed, which is a sign of a downdraft.

Difficulty Lighting a Fire

If you find it difficult to get a fire started, or if the fire goes out frequently, it could be due to downdraft.

Ash in the Room

If you notice ash in the room, it’s a sign that the fire is not burning as hot as it should be. This is usually due to downdraft.

If you notice any of these signs, it’s important to have your chimney checked by a professional. They will be able to determine if downdraft is present and can take steps to fix the problem.

How to Stop Downdraft in Chimneys?

The downdraft in the chimney is a very bad experience. It can make your warm moment unbearable in an instant by spreading smoke all over the house. There are several reasons why this can happen, and you can solve it by taking the proper steps.

1. Check Your Flue Liner

An underlined flue liner can create a downdraft by limiting the ventilation of smoke and hot air. Flue liners, usually made of ceramic or metal, form a shell on the inner wall of the flu. If the flu is too small, it will trap the heated air.

The heat causes the air to expand and if it’s already stuck inside a narrow stream, it can search for a separate path with less resistance like the interior of your home. Although replacing an undersized flue liner is not very easy, it’s worth investing in if you experience downdrafts with your fireplace.

2. Inspect Chimney Height

Many times the chimney height plays a role in the downdrafts of the fireplace. If your chimney is small, measured at the top of the roof of your home, it can create a downdraft. Air can enter smaller chimneys more easily than long chimneys.

Therefore, your chimney should ensure it is a suitable height. It should be 3 or 4 feet long. It can be expensive. Double-wall flues can increase in height by adding an extra length. If your chimney is lower than this height, your fireplace may be downdrafted.

3. Properly Construct and Clean the Chimney

A poorly constructed or broken chimney will cause a downdraft problem. You’ll find chimney smoke throughout the house. If this is the case, your chimney should be cleaned professionally. Proper chimney installation and regular cleaning can keep your home and your family safe. A clean chimney can give an effective fireplace.

4. Burn Kiln Dried Firewood

The type of fire you kindle in your fireplace should be evaluated first. If you keep burning fresh wood instead of burning dry wood, you can get a downdraft. Choose firewood with moisture content below 20% for proper combustion. Some believe that hats are the same as all firewood.

They burn locally sourced fresh wood with high moisture content. You can create a fire using fresh firewood with a high moisture content without any bad effects. But after a while, it will take a toll on your flue by contributing to the creosote buildup. The high humidity of fresh firewood prevents the combustion process, and it does not burn completely. As a result, it increases the risk of downdrafts by restricting airflow.

Kiln-dried firewood is usually valuable for low humidity. It’s processed using an advanced drying method known as ebb drying. During this process, the wood is placed in a heated oven, where moisture is released from its pores. Since it has less moisture than fresh firewood, as well as air-dried firewood, kiln-dried firewood has an efficient combustion process that produces very little or no glass. It is less likely to create a downdraft.

Kiln-dried firewood not only helps to protect against downdraft; It produces more heat.

5. Close Exhaust Vents and Windows

When using your fireplace, make sure that all the exhaust vents and windows in your home are closed. Exhaust vents are commonly used in bathrooms and kitchens. These are designed to ventilate indoors. They are used to disperse fog and hot air outside the house, while bathrooms use them to extract humid and humid air outside the house.

If an exhaust vent is on, it’ll pull your fireplace into the air, which can cause a downdraft. So make sure all the exhaust vents and windows in your home are closed before lighting your fireplace.

6. Wind Directional Chimney Cap

The wind-directional chimney cap is designed to direct the wind up and over the chimney, rather than allowing it to blow directly into the flue. This can help to improve the draft of the chimney and make it easier for the fire to draw. In addition, this type of cap can help to keep the smoke from your fire from blowing back into your home.

7. Use Anti-downdraft chimney

An anti-downdraft chimney is designed to keep the air pressure inside the chimney the same as the air pressure outside the chimney. This is done by having a damper that is located at the bottom of the chimney. The damper is opened when the fire is lit and closed when the fire is extinguished.

This way, the air pressure inside the chimney can never be lower than the air pressure outside the chimney. Anti-downdraft chimneys are a great way to prevent downdrafts from happening. They are also a great way to improve the efficiency of your fireplace.

8. Adjust the Damper

You can often prevent downdraft by adjusting the damper. You can keep the damper slightly open to make the fireplace work properly. If it’s completely closed, smoke and hot air will accumulate inside your home instead of coming out with the flue and chimney. If the outside air is fully open in the damper, the air may be forced to create a downdraft to allow the flue to enter.

How to Clean Your Chimney?

Wood fires often don’t burn cleanly, especially greenwood. The lack of chimney caps can cause stalks and leaves to accumulate in the chimney. Some insects, birds, and other animals can nest in chimneys or bring unwanted material. Sometimes they can be dead inside it, which can affect the flu. In short, for whatever reason, your chimney can be dirty.

Cleaning a chimney isn’t hard, but if it’s the first for you or if it hasn’t been cleaned in a long time, it would be the right decision to call a professional chimney sweep. You can complete the task of cleaning the chimney in 5 steps- 

First, open the damp completely. Go to the roof first. Use the extension ladder over the house for this purpose. Take your cordless drill and a dust mask.

Second, remove the chimney cap in this step. Remove the chimney caps by turning the screws on the caps with your cordless drill, and access the flu. Keep caps safe away from you.

Third, prepare the chimney cleaning brush. Turn the chimney sweeping brush over the first extension rod.

Fourth, scrub the chimney gently from top to bottom, leaving only one rod in the brush. Keep scrubbing until the first rod is finished. Then take the next rod and screw it to the back of the first rod. Thus continue scrubbing downwards by adding more rods if necessary.

Fifth, when the work is done, come down from the roof and wait a while for the dust and debris to be disposed of in the fireplace. Carefully spread the plastic over the firebox opening cover and bind it to trap any dust attached to the interior. Suck all debris with a shop vacuum and remove all equipment.

How Can I Improve My Chimney Draft?

If you are having trouble with the chimney draft you can do is to make sure that the flue is the correct size. If the flue is too small, it will not allow enough air to flow and this can cause problems with the draft. Another thing that you can do is to make sure that the chimney is clean.

If there is soot or debris build-up, this can also block the flow of air and cause problems with the draft. Also, you can try opening up the damper a bit more. This will allow more air to flow up the chimney and should help to improve the draft.

FAQs

What Are the Signs of a Chimney Downdraft?

Signs of a chimney downdraft include smoke or odors entering your home, difficulty starting a fire, or a fire that burns poorly or goes out quickly. You may also notice cold drafts coming from the fireplace when it’s not in use.

Can a Chimney Cap Help with Downdraft Issues?

A chimney cap can help with downdraft issues by preventing wind from directly entering the flue. Some caps are specifically designed to combat downdrafts, such as those with wind deflectors or rotating vents. However, a cap alone may not solve all downdraft problems, and other factors should be considered.

How Does Negative Air Pressure Contribute to Chimney Downdrafts?

Negative air pressure occurs when the air pressure inside your home is lower than outside. This can cause air to be drawn down the chimney, resulting in a downdraft. Common causes of negative air pressure include exhaust fans, HVAC systems, and tightly sealed homes.

How Can I Test for a Chimney Downdraft?

To test for a chimney downdraft, light a small piece of paper or incense and hold it near the fireplace opening. If the smoke is drawn up the chimney, there is no downdraft. If the smoke enters the room or moves erratically, a downdraft may be present.

What Should I Do If I Suspect a Chimney Downdraft?

If you suspect a chimney downdraft, consult a professional chimney sweep or technician. They can inspect your chimney, identify the cause of the downdraft, and recommend appropriate solutions to resolve the issue and ensure your fireplace functions safely and efficiently.

Conclusion

If you have a fireplace with a downdraft, refrain from using the fireplace. Downdraft can result in your chimney being filled with CO which is dangerous to the occupants of your home or its surroundings. This article has shown you how to stop downdraft in a chimney. If you suspect you have a CO in your home, the safest thing to do is to contact a certified professional and resolve it quickly.