What is Chimney | Complete Guide

A chimney refers to an architectural ventilation structure that is used to ventilate smoke or hot flue gases from a stove, boiler, furnace or fireplace to the outside environment. The chimney is made up of clay, masonry or metal whose major purpose is to separate hot toxic exhaust gases produced by a stove, boiler, furnace or fireplace from human living areas. We are all familiar with this whether one is using a wood-burning stove or a fireplace or any other thing, there is no way it can function without a chimney. A chimney is an engine that drives your wood heating system, the heat being the fuel.

Do you know, the more fuel you give to your chimney, the more powerful it becomes? And when you compare the working of the fireplaces, the more heat, the greater the draft. Now some of you might be wondering about what this draft is known as. Well, a draft is basically something that prevents smoke from entering your house while the heating system is burning. And for the record, a draft is good. Let us tell you that the insulated chimney liners help you in achieving the same thing by keeping the exhaust from being expelled hot until it reaches the outside.

What does a chimney in the kitchen do?

Some of you might be wondering what a chimney can do. Thus, we are here with the list of things performed by the chimney. Have a look at the list mentioned below:

  • A chimney in a kitchen makes lighting fires easy as the drafts build up faster.
  • With the help of the chimney, there is no smoke that comes out when you open the door to tend to the fire.
  • Chimney prevents smoke from entering your home.
  • With the help of a chimney in the kitchen, there will be no odors while the system isn’t lit.

Chimneys are vertical in order to make sure that gases flow smoothly, drawing air into the combustion. The space present inside the chimney is known as a flue. The best part about the chimney is that its height influences its ability to transfer flue gases to the external atmosphere with the help of the stack effect.

In a chimney, there is a second barrier, which is known as a flue liner that protects the masonry from the acidic products of combustion, this liner helps prevent flue gas from entering the house and reduces the size of an oversized flue. These liners can be clay or concrete tile, metal or poured in place concrete, but the most common is the clay tile flue liners. These liners are available in various sizes and shapes. Between each tile, refractory cement is used while constructing a new chimney. Metal liners may be aluminum, stainless steel or galvanized iron and may be rigid or flexible pipes. Among these metal liners, the aluminum and galvanized steel chimneys are called class A and class B chimneys among which class A is either an insulated, double wall stainless steel pipe or triple wall air-insulated pipe and class B are uninsulated double wall pipes.

Class A is often known by its genericized trade name Metalbestos, on the other hand, class B is often called B-vent, and is only used to vent non-condensing gas appliances.

 

About the structure of the chimney:

On the top of the chimney, you will find a chimney pot, which is used to expand the length of the chimney inexpensively and help you to enhance the draft of the chimney. Let us tell you an important thing about the chimney pot i.e. if a chimney contains more than one pot on it then it indicates that multiple fireplaces on different floors share the chimney. You will also find a cowl at the top of the chimney whose major purpose is to prevent birds and other animals from nesting in the chimney. In addition to this, they feature a rain guard to prevent rain or snow from going down the chimney to your home atmosphere. To minimize burning debris from rising out of the chimney and making it onto the roof, there is a metal wire mesh that is used as a spark arrestor. Inside a chimney, you will find masonry, which can absorb a large amount of moisture, which later evaporates and the rainwater can collect at the base of the chimney. At the bottom of the chimney, there are some weep holes that are used to drain out the collected water.

 Working of chimney:

When the oil, coal, wood, natural gas or any other fuel is combusted in an oven, stove, fireplace, industrial furnace or hot water boiler, then the hot combustion produce gases that are formed are known as flue gases, which are generally exhausted to the ambient outside air from these chimneys. The flue gases present inside the chimneys are much hotter as compared to the ambient outside air. Due to this, they are less dense as compared to ambient air which causes the bottom of the vertical column of hot flue gas to have a lower pressure than the pressure at the bottom of a corresponding column of outside air. This high pressure is the driving force that moves the flue gas up and out of the chimney. It moves the combustion air into the combustion zone. And the flow of combustion air is known as the chimney effect or stack effect.

Chimney maintenance:

The chimney in the kitchen and other places requires maintenance from time to time. But in most cases, there is no need to clean a gas chimney on an annual basis, but it does not mean that other parts of the chimney cannot fall into disrepair. Let us make you familiar with the important thing about the chimney that is loose chimney fittings can be caused by corrosion over time, which can further pose serious dangers for residents due to leakage of carbon monoxide into the home. Thus, it is suggested that chimneys be inspected annually and cleaned on a regular basis in order to prevent these problems.