Home Improvement

What is plenum height?

What is considered a plenum ceiling?

A plenum ceiling is one that uses the space between the top of the suspended ceiling and the bottom of the floor above to handle air for ventilation. All suspended ceilings are not plenums; some may use HVAC ductwork to move air to returns and diffusers located in the ceiling tiles (a ‘dead’ ceiling).

What is a plenum level?

Plenum levels are special levels that allow you to place spaces in the plenum areas above the ceiling by using a floor plan view based on the plenum level. You must place spaces in all plenum areas in order to perform an accurate heating and cooling loads analysis.

What is plenum floor?

An underfloor plenum is the open space between a structural concrete slab and the underside of a raised access floor system. Commonly used as the service plenum for distributing power, voice, and data cabling, in UFAD systems supply air is also delivered through this space.

What does plenum stand for?

A full or general assembly, as of all members of a legislative body. noun.

Where is the plenum located?

Plenum boxes are usually situated on either side of the fan or heat exchanger and have the important function of bringing in, distributing, and removing air. They are the air’s first stop after being heated or cooled and its last stop before going back into your AC, heat pump, or furnace.

Where is plenum required?

If you have a large wall or ceiling return air grate; remove and see if there the air is channeled through sheet metal ducting. 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.

What is plenum clearance?

5 Plenum clearances. Where the furnace plenum is adjacent to plaster on metal lath or noncombustible material attached to combustible material, the clearance shall be measured to the surface of the plaster or other noncombustible finish where the clearance specified is 2 inches (51 mm) or less.

How does a plenum work?

A supply plenum works by taking in the new cool or warm air from the heater or air conditioning system and, in turn, distribute it throughout the building using the HVAC’s ductwork. A return plenum takes in that used air and, using the ductwork, sends it back to the core HVAC system.

Is a drop ceiling a plenum?

Space between the structural ceiling and the dropped ceiling or under a raised floor is typically considered plenum; however, some drop-ceiling designs create a tight seal that does not allow for airflow and therefore may not be considered a plenum air-handling space.

Is a plenum necessary?

Q: Is a plenum necessary? A: In modern forced-air HVAC systems, you must have a plenum installed.

What is duct plenum?

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 supply plenum?

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.

What is plenum made of?

Plenum cabling is often made of Teflon and is more expensive than ordinary cabling. In the event of fire, its outer material is more resistant to flames and, when burning, produces less smoke than ordinary cabling. Both twisted pair and coaxial cable are made in plenum cable versions.

What is a plenum in plumbing?

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.

What is a heater plenum?

A plenum heater is an electric resistance heating device that’s installed in the open air space where ductwork and a furnace join. Air is heated as it flows across electric elements and then is distributed through the existing ductwork.

How big should a supply plenum be?

Single plenums should not exceed 24 ft in length. Double plenums should not exceed 48 ft in total length.

What is a furnace plenum made of?

This is due largely to it being made of sturdy metal (unlike most ductwork) and of course, the fact that you can’t actually “get to” your furnace plenum without disassembling things.

In which type of furnace is the plenum located on top?


This is the piece of your air conditioning system that most people never see. It’s contained in a metal box called a plenum, and sits on top of your furnace. If you have a horizontal furnace in an attic, the evaporator coil will sit on one end of the furnace instead of on top.

What is the difference between a plenum and 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.

How hot does a furnace plenum get?

The temperature rise from return to supply is usually between 40 and 70 degrees. A reasonable operating temperature would be 140F.

Should I insulate my furnace plenum?

sealing them helps your system more than just the condensation problem. Plenum should be dry before external insulation is applied. Duct wrap fiberglass insulation…all seams need to be sealed to keep moisture out, otherwise sweating may occur between wrap and sheet metal, causing insulation to be damaged.

What type of insulation is used for plenum?

blanket insulation

Plenum wrap is a blanket insulation that has a robust fire rating and is commonly used in plenum spaces. It is made from inorganic fibers that are encased in a scrim-reinforced foil, and it can withstand exposure to specific fire conditions for 1-2 hours.

Is a plenum an unconditioned space?

Plenum is a space below an insulated roof and above an uninsulated ceiling. It is an indirectly conditioned space as there is less thermal resistance to the directly conditioned space below than to the ambient air outside.

Does supply plenum need to be insulated?

simple answer…all supply plenums and ductwork, fittings, etc. is required to be insulated, and only after sealing all joints/connections with either approved foil tape or mastic material.