Blocked Chimney: Causes, Signs & Fixing Clogs

Chimney blockage is a risky situation that needs to be avoided at all costs. The level of risk is better appreciated when you consider the functions performed by chimneys.

Chimneys are built to vent out combustive gases while also drawing in air to support combustion.

By-products of chimney combustion include carbon monoxide. This gas is poisonous and gets even deadlier with sustained inhalation. With a functional chimney, such carbon monoxide gas should be safely channeled out through the vent.

However, this isn’t the case with a blocked chimney.

Things That Cause Chimney Blockage

Depending on the fuel being used or combusted, creosotes are released and steadily accumulate along chimney liner walls. While they add to the mess that needs to be cleaned, these alone won’t be sufficient to clog chimneys.

You may have to consider other possible reasons why your chimney gets clogged. Apart from creosote accumulation, other things to consider include tree foliage, trash, and other forms of debris.

The most worrisome include animal presence and activity.

When it comes to chimneys, animals like raccoons, rodents, and birds readily take up residence. This is most common during sub-zero temperatures when most animals seek warmth.

Apart from being present within your chimney, birds will readily build their nests using all sorts of materials.

Rodents will also pick up twigs among several other things to make their nests within chimney structures. All of these nests coupled with the presence of such animals create clogs within your chimney.

Being preoccupied with solving the effects of blocked chimneys alone won’t be sufficient. You’ll need to go further by investigating the causes of such clogs. This goes together with identifying tell-tale signs of blocked chimneys.

Now, this is where we delve into our conversation properly.

About Chimney Blockage

To identify the causes of chimney clogs, you also need to know the signs to look out for.

To aid with better understanding, we’ll be taking a separate look at the causes of chimney blockage as well as the signs of chimney blockage.

i. Causes of Chimney Blockage

For a chimney to be blocked there’ll be one of the following; the collapse of the internal chimney bricks or structure; a significant accumulation of soot and creosote; and the presence of small animals that find your chimney attractive.

  • The Collapse of the Internal Chimney Bricks or Structure

Over time as a chimney gets old, the brick structure begins to give way. This could be due to freeze and thaw cycles or acidic action. In the case of acidic action, the acid comes from certain oil fuels that contain sulfur.

As combustion occurs, sulfur released meets with moisture, thus forming sulfuric acid.

This condenses on bricks which sets a steady and gradual corrosive action. This corrosion expands bricks, thus leading to instability. Such bricks begin to crumble or give way.

Sometimes, the collapse of internal bricks may be due to a lack of chimney maintenance among other possible reasons.

  • Significant Accumulation of Soot and Creosote

When soot and creosote are left to steadily accumulate, what results in an excessive buildup situation. Asides from the possibility of igniting chimney fires, excess soot and creosote will also block chimneys.

Such blockage may either be partial or full.

Whatever the case is, your chimney system won’t function at full capacity. This problem can be solved by calling for a thorough cleanup of your chimney to remove such clogs.

  • Presence of Small Animals

The presence of small animals in chimneys raises a lot of concern for homeowners. These will create blockages to your chimney vent by building their nests.

We’ve discussed this earlier by highlighting the ways by which chimneys get clogged as a result of animal activity.

The adoption of preventive action such as the installation of chimney screens is a great way to start. You may have to change your chimney cap for one that has a screen or install such a screen to an existing chimney cap.

ii. Signs of a Blocked Chimney

When a chimney becomes blocked, it begins to malfunction. Now, you may have difficulty pointing what the problem unless you have an understanding of the common signs associated with blocked chimneys.

We’re providing all of that right here.

Like the cause mentioned above, there are also several tell-tale signs to look out for in chimney problems. They include excess soot, smoky fire smell, white residue on your flue walls, and falling debris inside the hearth.

You’re likely to also find water streaks appearing inside the flue. All of these should raise suspicions of a chimney blockage.

  • Excess Soot

Excess soot is one of the first things that should alert you to the possibility of a blocked chimney system.

Using a flashlight simply inspect the internal areas of your chimney. Your findings should be enough to call a chimney service or sweep.

This is another tell-tale sign that your chimney is blocked. As combustion occurs, creosote deposits which are in the form of tar may ignite when the chimney is clogged.

With nowhere to go, gases from combustion permeate your home. Exposure to such gases is also dangerous health-wise.

  • White Residue on Flue Walls

You’ll need to pay attention to your flue walls when inspecting for possible chimney blockage. Are there white deposits or residue of any sort? If so, you need urgent help to unclog your chimney.

  • Falling Debris

Falling debris is common to clogged chimneys.

Excess accumulation of soot and creosote leads to falling off of debris to the hearth. Whenever you find such debris scattered over your hearth, never take such lightly.

Call for Inspection and Cleaning

Having carried out a rudimentary inspection as provided above, it’s necessary to call the pros to perform a thorough inspection job. This is performed by a chimney sweep that clears out all clogs, thus freeing your chimney vents.

When the causes for chimney clogs are seen to be more severe, drastic action is taking. In the case of a faulty chimney, some intrusive maintenance actions may be necessary.

With the information provided here, you have a better understanding of how to detect chimney clogs. We’ve also mentioned that it’s best to let the pros perform a thorough inspection and maintenance job.

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