What is plenum height?

Asked By: Anunciata Suriel | Last Updated: 2nd February, 2020
Category: home and garden indoor environmental quality
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In building construction, a plenum (pronounced PLEH-nuhm, from Latin meaning full) is a separate space provided for air circulation for heating, ventilation, and air-conditioning (sometimes referred to as HVAC) and typically provided in the space between the structural ceiling and a drop-down ceiling.

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Furthermore, what is considered a plenum space?

A plenum space is a part of a building that can facilitate air circulation for heating and air conditioning systems, by providing pathways for either heated/conditioned or return airflows, usually at greater than atmospheric pressure.

Beside above, how do I know if I have a plenum ceiling? If the space above the drop ceiling is used for environmental air transfer, meaning the air above the drop is apart of the air return, then it is a plenum area and plenum rated cables shall be installed.

Correspondingly, what is the purpose of a plenum?

A plenum chamber is a pressurised housing containing a fluid (typically air) at positive pressure. One function of the plenum is to equalise pressure for more even distribution, because of irregular supply or demand.

Do I need a return plenum?

Return air plenum is not required. Bottom return air is alot better than pulling from one side of the furnace, the blower motor and CFM is more efficient. Duct work is sized by the tonage of the A/C system and number of heat runs in the house.

38 Related Question Answers Found

Is plenum required for residential?

If there is no sheet metal duct; just the open ceiling or wall space, then you are required by law to use Plenum Rated cable. The lack of wall or ceiling return air grates is usually a sure sign that you require Plenum Rated Cable. Computer Rooms typically use a raised flooring system for the server racks.

What is the space between floors called?

An interstitial space is an intermediate space located between regular-use floors, commonly located in hospitals and laboratory-type buildings to allow space for the mechanical systems of the building.

What is plenum vs non plenum?

Plenum cables are run in that space (the plenum) to minimize the hazard from burning cables in a fire. Non-plenum, often called riser cables are less expensive and are used in spaces that do not intermingle with normal air circulation: attics, closed walls, conduit, etc.

How big should a plenum be?

The plenum length would be 2 x 40 or 80 inches long. Also, no branch connections would be made at any point on the box plenum that is within 2/3 x 16 or 10.67 inches of the entrance side. As a comparison, the minimum recommended plenum size would be -- width: 2 x 16 or 32 inches; length: 1 x 36 or 36 inches wide.

What is plenum rating?


Plenum rated cable has a special insulation that has smoke and low flame characteristics. It is mandated to be installed in any “air handling” space. For instance, most large office buildings use the ceiling to return air to the AC unit.

What is a plenum in HVAC?

A plenum is an air-distribution box attached directly to the supply outlet of the HVAC equipment that heats or cools the air to make the house comfortable. The ductwork that distributes the heated or cooled air to individual rooms of the house connects to the plenum.

What is the difference between a plenum and a duct?

As nouns the difference between duct and plenum
is that duct is a pipe, tube or canal which carries air or liquid from one place to another while plenum is (physics) a space that is completely filled with matter.

What is an open air plenum?

Plenum spaces are the open spaces above the ceiling or below the floor that are used for air circulation. Technically, any ductwork is considered a plenum space too.

What is a plenum cover?

Plenum in car is a storage container for charge which is connected to the the intake manifold. Its basic use to provide the extra charge during intake which is stored in the plenum chamber which will help you to give good torque and acceleration.

Is an open ceiling considered a plenum?


An open ceiling in a retail store would not be a plenum area. If this was the case all the merchandise would need to be rated to be installed in environmental air ducts.

How does a plenum ceiling work?

A plenum space is a part of a building that can facilitate air circulation for heating and air conditioning systems, by providing pathways for either heated/conditioned or return airflows, usually at greater than atmospheric pressure.

How does plenum ventilation work?

a system of mechanical ventilation in which fresh air is forced into the spaces to be ventilated from a chamber (plenum chamber) at a pressure slightly higher than atmospheric pressure, so as to expel foul air.

What does plenum mean in HVAC?

In building construction, a plenum (pronounced PLEH-nuhm, from Latin meaning full) is a separate space provided for air circulation for heating, ventilation, and air-conditioning (sometimes referred to as HVAC) and typically provided in the space between the structural ceiling and a drop-down ceiling.

Where is the plenum located?

A supply plenum is an enclosed compartment that's located just after your heat exchanger if you follow the flow of air through your furnace (see below). When your air handler blows air over your system's heat exchanger, that warm air is directed into the supply plenum.

Is an attic considered a plenum?


According to every dictionary I looked at, the area below the roof of a home and above the ceiling joists is considered an attic, regardless if it is conditioned or not. In this case it would be a conditioned attic. Wiring within a plenum does not have to be in conduit.

What is the difference between plenum and riser cable?

Many customers ask, “What is the difference between plenum rated cable & riser rated cables.” Plenum rated cables are used in plenum areas meant for use in commercial and residential spaces. Riser rated cables run between floors through cable risers or in elevator shafts in non-plenum areas.

What is the space above the ceiling called?

An attic (sometimes referred to as a loft) is a space found directly below the pitched roof of a house or other building; an attic may also be called a sky parlor or a garret.