How a Furnace Plenum Affects HVAC Operations

November 20, 2022
Furnace in Somerset, KY

Taking good care of the HVAC system in your Somerset, Kentucky home starts by understanding how it works. When you know what each component is and what it does, you’ll have a better idea of how to maintain them. There are a number of critical components that often get overlooked. One of these is the furnace plenum. Read on to find out what furnace plenums do, why they matter, and how you can keep yours in excellent condition.

Plenums and HVAC Airflow

Your HVAC ductwork is made up of ducting, dampers, reducers, take-offs, and many other components. Of these, its plenums are easily the most important. Also known as plenum boxes, these components are designed to distribute air in forced-air heating and cooling systems. Plenums handle air as it gets pulled in by your heater or air conditioner and recirculate it throughout the system for conditioning.

How Many Plenums Does Your HVAC System Have?

Every forced-air heating and cooling system has two plenums. These are the supply plenum and the return plenum. These boxes are often found in the basement or in other low-lying areas of the building. The supply plenum is attached to your furnace’s supply outlet. This unit provides the air that your furnace heats. The air from the supply plenum is pushed into the branches and trunk lines of your HVAC ducts.

The return plenum, much like its name suggests, returns air to your furnace. It has its own built-in air filter for removing dust, dirt, mites, dander, and other small-sized particulates that might harm your heating and cooling equipment. If you’ve ever performed HVAC air filter changes before, you’ve probably encountered this unit already. If not, talk with your HVAC technician to find out where it is and to learn more about changing its filter.

Return plenums are easy to access. Supply plenums are not. Some HVAC systems have air filters in both plenum boxes. However, if there’s a filter in your furnace’s supply plenum, you don’t have to change its filter on your own. Although you should change the filter in the return plenum about once every one to three months, the supply plenum filter will be inspected and changed by your HVAC technician during the annual maintenance service.

Furnace Plenums Play an Important Role in Keeping Homes Comfortable

When the plenum boxes in your HVAC system are working efficiently, they’ll help you maintain reasonable home energy bills. When these components wear down, malfunction, or outright fail, you’ll likely see rapid and significant increases in your heating and cooling costs.

Furnace plenums also have a hand in ensuring quiet HVAC operation. If you have a noisy furnace, an old or damaged plenum could be the culprit. Scheduling service is a great way to identify and address plenum problems before they spiral out of control. Using your furnace with a broken plenum can lead to HVAC system failure.

What You Need to Know About Caring for Your Furnace Plenum

There are many good reasons to perform regular HVAC air filter changes. This simple maintenance task can save you a considerable amount of cash over time by keeping your heating and cooling equipment at optimum levels of efficiency. It can also protect and even improve your indoor air quality (IAQ).

However, the benefits of regular furnace filter changes also extend to your home heating equipment. After all, the primary function of the filter in your furnace’s return plenum is to keep airborne particulates out of your furnace and away from its sensitive interior components. The IAQ benefits that filter changes provide are secondary to this.

You can check the owner’s manual for your furnace to determine the best filter change schedule for your household. However, you may want to change your furnace filter more often than your manual recommends if you:

  • Have one or more indoor pets
  • Live in a high-traffic location
  • Live in a dusty neighborhood

You should also schedule annual maintenance for your air conditioner and your furnace without fail. HVAC professionals can find, access, and take care of the supply plenum during this process. Moreover, if this plenum box has a filter, they’ll make sure that it’s cleaned or changed on schedule.

Jeffries Heating & Air is a trusted provider of HVAC services throughout Somerset, Kentucky and the surrounding area. We offer heating, cooling, and plumbing system installation, maintenance, and repairs. We also provide drain cleaning services and water heaters. We’ve got answers if you’ve got questions about your furnace plenum. Call us today to schedule an appointment!

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