HVAC Ducting

When you think of your HVAC system, you might think of the bulky air conditioners that sit outside your home or the furnace in your basement. You might even think about the vents in your bedroom, living room, or kitchen. But have you ever stopped to think about the metal channels that connect your air conditioner and furnace to those vents? These metal channels are called the ductwork, and it forms an integral part of your HVAC system.

In this article, we’re going to go through the main parts of your HVAC system’s ductwork, how they work, and when (and why!) they may need to be replaced.

Main Parts of Your HVAC Ductwork and How Do we Work

There are several HVAC duct components that make up your HVAC system. Here are some of the main parts:

Ducts (Pipes and Trunks)

The duct pipes and trunks in your home and made of several different components. Simply put, the duct pipes and trunks are the main channels that connect to the air handler and provide a conduit for warmed or cooled air to be blown throughout your home. The duct trunk is the large main trunk, while the duct pipes connect that trunk to each room of your home.

Most of the time, these trunks and pipes are made of galvanized steel but, for places where your walls need a more bendable option, flexible aluminum can also be used. This aluminum is generally called flex piping in ductwork.

Besides the trunk and pipes, there are other ducts that bring air into very specific places within the home. For example, a tall, thin, vertical duct pipe is called a stack, which allows air to be blown vertically through a thin wall. Stack heads are found at the end of this type of duct pipes.

Duct Transitions

Obviously, these ducts need to be connected according to the shape of the home if your HVAC system is to work efficiently. There isn’t a one-size-fits-all approach to HVAC systems, so these duct trunks and pipes must be connected using duct transitions.

Duct trunks and pipes can be connected by take offs, turning vanes, cleats, and other specialized connectors and can also end with angled boots. These elements work together to create pathways through your home that bring comfortable air into your living spaces.

Plenum

A plenum is essentially a large box that stores air for the HVAC system and that is connected to the various ducts. There are usually two plenums of your HVAC system’s ductwork; the supply plenum and the return plenum. The HVAC system will fill the supply plenum with heated or cooled air, which then is sent through the ductwork of the system. When this heated or cooled air enters a room, it pushes the already-present air out of the room into another set of ducts. These ducts deliver this returned air to the return plenum. Depending on your HVAC system, the returned air is then either funneled outside through a flue or filtered and sent back through the heating and cooling process.

Flues

Flues bring air outside. Generally, these are found in HVAC systems were noxious fumes are created through the heating or cooling process. These gasses are vented outdoors through the flues. If your return plenum does not recycle returned air, it might be vented outside through a flue.

Refrigerant Lines

The refrigerant lines inside the HVAC system bring refrigerant into the compressors. This refrigerant allows your HVAC system to cool or heat your air.

Air Handler

The air handler in the HVAC system is where the blower fan and filter are located. The blower fan moves the air through the ductwork. The air handler also may include the heating or cooling coils. 

Drain Pans and Lines

HVAC systems are designed to heat or cool the air, but they usually dehumidify the air as well. That means that condensation can build up within the system, which is why drain pans exist. They take the water that has been created during the heating or cooling process and drain it using the drain lines outside of your home. Without drain pans in your ductwork, you would end up having rust or mold inside your home.