How Does Forced-Air Heat Work? - Live And Love Out Loud

How Does Forced-Air Heat Work?

It may not be something you often think about, but there is a great deal of engineering ingenuity throughout your home. Consider how many of the things we take for granted daily that are actually brilliant inventions that we’ve come to rely on. Dishwashers, clothes dryers, showers, the list goes on and on. Few of these inventions are more important, however, than the ability to safely heat your home during the coldest times of year. Without this vital technology, life would be far more difficult—and often dangerous—for the inhabitants of some of the coldest regions of the world.

Most modern homes utilize a method called forced-air heat to stay warm when the mercury drops. Read on to learn a little about how this critical part of winter survival works.

Where Does the Heat Come From?

To generate heat, you will need to begin with a fuel source. There are several you can choose from for forced air. Which is the best depends on what is available in your area and your home’s specific needs. It’s a good idea to do a little research before committing to one particular heating method.

All matter contains thermal energy. When the molecules of a substance are excited by an outside force, that energy is released in the form of heat, light, or both. A substance that produces more light than heat can make for a great source of artificial light—think of the tungsten in a traditional incandescent lightbulb—but it will be an inefficient heat source.

The best fuel sources are materials that release a lot of heat when they are ignited, and these substances usually contain compounds that react well with oxygen during the process of combustion. Think of wood, for example—the high carbon content is what causes wood to burn so well when you start a campfire.

The most popular modern heat sources are natural gas, which is a hydrocarbon compound that is mined from within the earth, and propane, which is a type of petroleum gas that can be pressurized into a liquid for easy transport. Both of these substances burn very hot and clean, making them efficient fuel sources for home heating.

There are other ways to generate heat that don’t involve burning anything. Electric resistance heating, for example, uses an electric current passed through a medium to release thermal energy. Other heating methods, such as heat pumps, don’t generate their own heat at all, instead making use of the thermal energy that exists in the ambient air or ground outside the home.

It All Starts in the Furnace

All of the above methods, except the heat pump, use a furnace to generate the thermal energy that is required for heating. If the furnace is burning a combustible fuel, such as natural gas or propane, then it will also generate potentially toxic byproducts, such as carbon monoxide, as it does so. This means that the furnace must be installed somewhere where the exhaust containing the waste products can be safely vented outside of the home, without any risk of the inhabitants breathing them in. Basements are popular for this, as long as proper ventilation can be created.

Note that, while electric furnaces do not generate these toxic byproducts, the fact that they are creating a lot of heat means that you will still need to take safety into consideration. Always install any furnace in an area where it has plenty of space around it so there is no risk it will inadvertently start a fire in your home.

Your furnace contains several mechanisms to facilitate the safe and effective generation of heat. In a gas or propane furnace, the fuel source is pumped into a burner, where it is combusted. In an electric furnace, voltage is pumped through a medium that begins to heat up when electricity is applied.

Transferring Heat From One Place to the Next

Once the furnace has begun to generate heat, it must then be transferred from the fuel source into the air. In most forced-air heat systems, this is done using a device called a heat exchanger. Inside the heat exchanger, air or another fluid medium is pumped through a coil. Since the fluid in the coil is of a lower temperature than the burning fuel source (or electric resistance medium), the laws of physics dictate that the heat energy will begin to move into it until a state of equilibrium is reached.

The ultimate outcome of this is that there will now be a coil full of very hot air, but which contains no carbon monoxide or other harmful chemicals. The next step is to get that hot air out of the furnace and distribute it into every room of the home.

How Air Is Circulated Throughout Your Home

In a forced-air heating system, the furnace is connected to a system of ducts that wend their way throughout every room of your home, hidden away behind walls or above ceilings. These ducts are made from a material that is lightweight but also serves as a good insulator, such as aluminum, so that the heat energy will not easily be conducted out of them.

Each duct terminates at a vent, of which there is usually at least one—and sometimes several—per room in the home. Whenever the heating system is switched on, a large fan will activate and blow the hot air through the ducts. It is then forced to exit through the open vents, where it begins to fill up each room in the home. The process of convection then causes the heat energy to transfer to the rest of the air, finally bringing your home to a comfortable temperature.

The constantly circulating air in a forced-air heat system can carry with it a lot of dust and dirt. While most of this is caught by the filtration systems in the furnace, those filters and the ductwork will become dirty and less efficient over time. For this reason, you should contact a heating and cooling professional from a company like Entek HVAC to periodically replace the filters and perform cleaning and maintenance on your forced-air heating system.

In fact, regular maintenance of your forced-air heater can help keep the system running smoothly for many years, keeping your home warm and comfortable all winter and saving you money. Talk to your local HVAC professionals about a checkup today.