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What Are Return Air Plenums & How Much Do They Cost?

Return air plenums are the ducting units used as the central chamber for return air ducting. Furnaces and air handlers should have a return air plenum so that they can operate at their maximum efficiency. Return air plenums recycle the air in a structure back to the air handling unit and exhaust the air out of the home.

The Costs 

  • Minimum Cost of Return Air Plenums: $50

  • Maximum Cost of Return Air Plenums: $60

The cost of return air plenums fluctuates based on the individual manufacturer. Because the product is a single unit device, it is easy to compare prices between brands. Generally, a return air plenum will cost approximately $50 to $60 per unit. The other costs to consider are those for the labor and materials needed to install the return air plenum. The installation takes an average of about five hours with the sum of labor costs between $290 and $370. Also, the supplies and tools necessary to complete the installation range between $25 and $35. In total, a consumer should expect to pay a cost ranging between $365 and $460 for the return air plenum unit, installation and supplies.

Advantages of Return Air Plenums

There are a number of advantages to installing a return air plenum over a ducted return system. One major advantage to return air plenum systems is that they are cheaper to install from a mechanical basis because less ductwork is required; the need for all return air ductwork is completely eliminated. In addition, there are reduced relief system costs as relief fans and non-powered relief fans are cheaper than return fans.

They also reduce the amount of energy used and are self-balancing, so they remove the need for balancing labor. Return air plenums also normally lessen the necessary depth of ceiling space. Shafts can be smaller as the complete open section of the shaft and ceiling are accessible for the return airflow.

Disadvantages of Return Air Plenums

Although this type of system can be beneficial for certain homeowners, there are some potential drawbacks. When installing a return air plenum system, it is absolutely essential that the system is constructed airtight without any leaks above the ceiling space; with return air plenums, there is less control over where the air actually travels. When installing return air plenums, all wiring such as telecommunication, electric and control wires must be plenum-rated.

Return air plenums, if not properly designed within the ducting framework, can cause outdoor air to be drawn into the building. Therefore, if the building is located in a humid climate, condensation of moisture can occur from the outside air. This can eventually result in mildew and mold growth within the building structure if a dehumidifier isn't used. It is also a possibility that return air plenums could lead to health issues within a building due to the possible buildup of dust and debris on ceiling tiles and other areas.

There may be building codes that specifically prohibit return air plenums. Most codes only permit the use of return air plenums if the materials that are exposed to the plenum satisfy particular smoke generation and flame spread limits.

Last updated on Sep 8, 2014

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