Why Your Fireplace Is Smoking

10 Reasons Why Your Fireplace Is Smoking

In Indoor Fireplaces, Wood Burning Fireplaces by James O'KellyLeave a Comment

It can be a nuisance having fireplace that produces smoke.

There may also be times that any smoke produced seems to enter your home, rather than escaping up the chimney. There have also been plenty of times when we’ve had the smell of smoke linger in the house for hours after a fire!

There are two short answers as to why your fireplace is smoking:

The fire is producing smoke
Any smoke produced is not leaving your fireplace

There can be a number of different issues that could be causing your fireplace to smoke, including the size of your fireplace, the size and height of your chimney, the layout of your room and even the type of wood you are burning.

A fireplace can smoke for different reasons. The cause of the smoke can be situational, such as the type of wood being burnt of the current outside weather, or constant, such as a lack of draft up the chimney.

So whether the fire in your fireplace is smoking, or smoke is coming into your home rather than up the chimney, I’ve put together some of the most common reasons why your fireplace is smoking.

Burning Wood With High Moisture Content

If you’ve recently bought a new batch of firewood and you’re finding that it’s smoking a lot more than usual, it may be that the wood is too wet to burn.

To be efficient at burning in a fireplace, wood needs to have a moisture content of 20% or lower.

The higher the moisture content of wood, the harder it is to light and the harder it is to burn, and therefore the more difficult it is to keep the fire going. This is because it takes a lot more energy to burn off the excess moisture within the wood. When the wood isn’t being burnt properly, the fire releases smoke.

As a result, burning wet wood releases a lot more smoke than burning dry wood.

You want to be burning wood that has a low enough moisture content that it will light easily, keep burning and release as little smoke as possible.

Before burning firewood in your fireplace, look for the signs that the wood is dry enough to use:

  • The wood is darker in color
  • The wood doesn’t have a ‘fresh’ smell
  • Knocking pieces of the wood together makes a hollow noise
  • Any bark present is coming off
  • The wood is splitting at the ends

You can also use a moisture meter to read the exact moisture content of your wood.

The Damper Is Closed

A damper is a metal or ceramic grate that can usually be found just inside the top of the fireplace at the base of the chimney. If this isn’t the case then it may be located at the very top of your chimney.

If your damper is located at the top of the fireplace, check for a handle that can be used to open and close the damper. There may also be latches on the handle to enable the damper to be left partially open or closed.

If your damper is located at the top of the chimney, you should have a metal chain located to the side of the inside of the fireplace. When the chain is hooked on the inside wall of the fireplace, the damper is closed. When the chain is unhooked, the damper will pull the chain up and automatically open.

One of the main functions of a damper is to prevent warm air from escaping your home when the fireplace isn’t being used. When closed, the damper will help stop warm air from being replaced by cold air from the outside in the winter, or even help stop air conditioned air in your home from being replaced by warm air in the summer.

If your damper is closed or partially closed, the draft from the chimney can be insufficient enough to cause your fire to produce smoke.

The damper should always be fully opened before a fire to ensure safe passage of waste smoke and gases from your home.

Keeping your damper wide open will allow a greater suction from the chimney, in turn feeding more air to the fire and helping the fire to produce less smoke. Any smoke that is produced will be vented from your home up the chimney.

Blocked Or Partially Blocked Chimney

Burning wood can produce smoke and other harmful gases. You chimney is the gateway for any smoke and gases to leave your home, and so it’s important to periodically have your chimney swept in line with recommended guidelines.

A blocked or partially blocked chimney can reduce the draw of your chimney causing the fire to produce more smoke, and can also prevent any smoke from leaving your home.

A partially blocked chimney can reduce the draw your chimney, reducing its ability to suck air from the fire. In sucking air from the fire, the draft from the chimney will also pull fresh air into the fireplace to feed the fire.

If you find that your fireplace is constantly releasing smoke then a blocked or partially blocked chimney can be one of the most common causes.

In order to maximize the efficiency of the chimney draft, and therefore the air supply to your fire, chimneys should be swept at least once a year to prevent the buildup of soot and creosote within your chimney.

The best time to have your chimney swept is just before the winter season when you are most likely to be using the fireplace, as other blockages such as bird nests can buildup in the chimney over the warmer months.

Creosote is a highly flammable substance that is released from burning wood, and can increase the risk of a chimney fire if not removed.

If burning wood in your fireplace regularly, recommended guidelines state that your fireplace should be cleaned every season.

You can also use a torch or the flash on your phone to take a look up your chimney and inspect it for any blockages.

Here’s the view up our chimney from the fireplace in our living room:

Chimney From Fireplace
The View Of Our Chimney From The Fireplace

No blockages here!

Cold Air Within Chimney

Cold air sinks, and hot air rises. If the air within your chimney is cold then it may be pushing down on the waste gases from the fire that are trying to escape up your chimney.

Cold air trapped in the chimney can prevent hot air from leaving your fireplace, leading to inadequate airflow to your fire and potentially causing the fire to start smoking. A fire that is burning more slowly due to lack of oxygen is more likely to produce more smoke.

This can be a common cause on especially cold days, and can be made worse by having a chimney that is located on an external wall in your home.

The air in your chimney may need to be warmed up. If you have a damper that is closed, leave it open for at least 30 minutes before using your fireplace to help the air in your chimney to warm up.

To clear the cold air in your chimney and to start the draft, you can use a heat source to speed up the process. Lighting a small amount of crumpled newspaper or firelighters in your fireplace can help warm up the air in the chimney before a fire.

You can also take a piece of newspaper and roll it up. Light the end of the newspaper and hold the flame at the top of the firebox, at the base of the chimney. The smoke produced from the newspaper will tell you whether there is sufficient draft up the chimney. Once the smoke is being sucked up the chimney you can start a fire in your fireplace knowing that any smoke produced will leave up the chimney, rather than out into your home.

Even lighting a candle in the fireplace before a fire can help. We’ve even used a hairdryer to warm up the air in the chimney on very cold days!

Follow this up by starting the fire with pieces of quick lighting and fast burning bits of kindling. This will get the fire hot quickly, therefore speeding up the warming of the air in the chimney and maximising the draft as soon as possible into the fire.

Insufficient Chimney Size & Height

It may be case that your chimney isn’t tall enough to provide sufficient draft for the fireplace.

In general, the taller the chimney the greater the draft can be provided to your fireplace.

The chimney height in relation surrounding structures, such as your roof and other nearby buildings, can also play an important role in how well your chimney operates. If a chimney is located down wind of a structure, turbulence from that structure can cause downdraft problems in your chimney.

If your chimney isn’t at the height required to provide sufficient draft to your fireplace, you can look into getting a flue stretcher cap that increases the height of your chimney.

On the other hand, a chimney can also be too high. If a chimney is too tall then this can cause the rising warm air to cool down too soon and to stop rising any further.

Poor draft can also the case with a chimney opening that it too large in diameter compared to the size of your fireplace.

Poor Ventilation

As with poor draft up the chimney, poor ventilation can lead to a smoking fireplace. There needs to be sufficient supply of air to the fire to enable it to burn the wood efficiently.

If you have an air vent in the room where your fireplace is located, be sure to fully open it before starting a fire.

Here’s the vent in our living room for use with our open fireplace:

Fireplace Vent
Our Fireplace External Room Vent

It’s easy to forget to open a vent like this, we’ve forgotten many times!

A well insulated home can also be a cause of smoke coming from your fireplace. Try to keep the doors of your room open when using your fireplace, or open a window to provide more ventilation to the fire.

Tip: Opening windows on the bottom floor of your house rather than windows higher up will be much more efficient. Windows opened even a few centimeters should be sufficient.

Location Of The Fireplace Grate

Locating your grate too near to the front of the fireplace may lead to any smoke bing produced by the fire coming into your home, rather than going up the chimney.

To try and help prevent this issue, move your grate further towards the back of the firebox.

You can also buy taller and thinner grates that allow for your fire to be made higher up in the fireplace. This allows for the fire to be centered more towards the back of the fireplace and helps provide less room for any smoke to make its way out of your fireplace.

Oversized Fireplace

If your fireplace consistently produces small amounts of smoke that leaks into your home, it could be that your fireplace is oversized for your size of your chimney.

To overcome this problem, a smoke guard can be installed within the top of your fireplace opening to reduce the overall opening size of your fireplace.

This can improve the draft of your fireplace, and can also reduce any smoke that is produced by a fire from making its way into your home.

High Winds

If your fireplace is smoking during periods of high winds, it may be that case that the winds are forcing a downdraft within your chimney, preventing sufficient draw for your fireplace.

Some chimney caps can help reduce this problem by deflecting high winds away from your chimney opening, and may even help provide more suction up the chimney.

As this is a very situational reason for a fireplace to be smoking, it may be a simple case of waiting for the high winds to subside before using your fireplace.

Unclean Fireplace

A fireplace that is too full of ash and left over burnt bits of wood can prevent the fire from receiving sufficient airflow.

It’s good to leave approximately an inch of ash, but any more may smother the fire.

A constant and sufficient flow or oxygen to the fire is essential for creating and sustaining a hot fire, which in turn will help produce a greater draft up the chimney.

When you’re adding larger bits of wood to the fire, be sure to also leave gaps to allow for more airflow between the logs.

How To Stop Your Fireplace Smoking

Have your chimney swept at least one per year, but more often if you regularly burn wood in your fireplace.

Open the damper as wide as possible before using your fireplace

Use kiln dried or well-seasoned logs, as wet wood is more likely to produce smoke.

Open any vents, doors and windows to provide more ventilation to your fireplace.

Clean any excess ash out of your fireplace periodically to ensure a sufficient and constant supply of air to the fire.

On colder days, warm up the air in your chimney using a small heat source to help start the draft up your chimney.

Why Your Fireplace Is Smoking

The reasons why your fireplace is smoking can be very situational or can be down to an ongoing problem.

In terms of situational issues of a smoking fireplace where the fireplace may not be smoking every time you use it, here’s the reasons why your fireplace may only be smoking some of the time:

  • Using the fireplace in high winds
  • Burning high moisture content wood
  • Cold air within the chimney
  • Too much ash in the fireplace
  • The fire is being made too near the face of the fireplace
  • Poor ventilation within the room

If you’re finding that the issue of a smoking fireplace is constant throughout it’s use, there may be more overlying issues that need to be addressed. These can include:

  • A damper that isn’t open or open enough
  • A blocked or partially blocked chimney
  • Insufficient height on chimney to produce require draw on the fireplace
  • An oversized fireplace in relation to the chimney opening size

By going through each of these points you can hopefully find the reason, or reasons why your fireplace is smoking.

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