Why Do Hot Air And Smoke Go Up A Chimney? (Find Out Now!)

As we all grow up, we have all been able to make the same observation about hot air and smoke: They rise. So when you light a fire in a fireplace or elsewhere, the hot air and smoke both rises. Although this phenomenon seems to be common knowledge, have any of us ever stopped to consider why this happens? How does the majority of the hot air and all of the smoke know to go up the chimney? We have the answer for you!

Smoke and hot air go up a chimney because of two primary reasons: One is that the fireplace is created from flame-resistant materials. The second reason is that the fireplace creates a draft that causes a stream of heated air in the fireplace, pushing the smoke up the chimney. Therefore, when the hot air rises, it draws more of the hot gases under it so that the smoke and hot air continue to rise.

In this article, we will dive deeper into the mechanics of a traditional fireplace. We will also provide you with some basic instructions on how to operate your fireplace the correct way to ensure your smoke is evacuating in the manner it should. As a bonus, we’ve included some vocabulary terms you should be familiar with so that you can better understand the operations of your fireplace.

When you light a fire in your living room, there are two main challenges. You have to ensure that the flames are contained within the fireplace so that there is no danger of setting the house on fire. Also, you need to prevent smoke from filling the room. Your fireplace is designed to avoid both of these eventualities.

First of all, your fireplace is constructed using flame-resistant materials, typically stone or brick, but sometimes metal or tiles. It also ensures smoke is evacuated efficiently by directing it up the chimney.

From a mechanical point of view, the essential job that your fireplace does is creates a draft. We all know that hot air rises: Just think of how a hot air balloon stays in the air. The fireplace creates a stream of heated air inside the chimney. As it rises, more hot gases are drawn up after it. As they rise up the chimney, a draft is created.

The draft has another essential function. All fires need a constant supply of oxygen to keep burning. As the hot air rises, it drags more fresh air, and therefore oxygen, onto the burning fuel.

Most of the heat that a fire creates is comprised of hot gas. When this moves up the chimney due to convection, it doesn’t heat the room but is wasted. Not only that, but the draft also pulls more warm air from the room up the chimney, which results in a reduction of the room temperature. In fact, certain experts claim that a traditional fire draws four to ten times as much air from the room as the fire actually needs to burn.

It can happen that the room loses more heat due to convection than it gains through radiation. This can result in negative energy efficiency. The lower the temperature outside, the colder the air that the fireplace draws in, and the lower the efficiency will be overall.

To get the fire going, you’ll need to start with some kindling. These are small pieces of wood that will catch fire easily. Pile a few logs into the grate and position kindling below and around them. Ensure the damper is open, then light the kindling with newspaper or a fire starting log.

Important Note: Never use a lot of paper, as burning pieces can travel up the chimney and onto the roof, creating a fire risk. For obvious safety reasons, never use gasoline, lighter fuel, or a blow-lamp to light your fire.

Even when the fire is burning, some might sometimes flow back down into the room. One reason this occurs may be that the house is too tightly sealed. Without enough ways that air can enter the room to replace that which is being pulled up the chimney, therefore creating negative pressure,f from which a partial vacuum develops.

This vacuum pulls air back down into the room to restore the air pressure, and the result can be a room filled with smoke. The simple solution is to open a window slightly to allow more air to enter.

Fireplaces are virtually self-sustaining mechanisms as far as the flow of smoke, and hot air goes. Minimal amounts of maintenance need to be done to encourage them to go to their rightful place: Up the chimney. However, sometimes you will notice that smoke is pouring out into your living room. If this happens, you simply need to crack a window or a door, and the problem will solve itself.

Learning the different elements of a fireplace and how they work together will help you better understand exactly how your fireplace functions. This knowledge aids you in understanding all there is to know about operating a fireplace safely. And yes, it even helps you understand exactly why hot air and smoke go up the chimney. Every always says that knowledge is power; however, knowledge can also aid in safety.