What does plenum mean in HVAC?

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.

What is the ASHRAE standard for indoor air quality?

ANSI/ASHRAE Standards 62.1 and 62.2 are the recognized standards for ventilation system design and acceptable indoor air quality (IAQ). Expanded and revised for 2019, both standards specify minimum ventilation rates and other measures in order to minimize adverse health effects for occupants.

Does a furnace need a plenum?

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

What’s the difference between plenum and non plenum?

Thus, fire and building safety codes mandate plenum-rated cables be used in plenum spaces and air ducts. They can also be used in non-plenum areas. Non-Plenum cables, on the other hand, are much cheaper and not as fire-resistant. When burned, they release toxic fumes such as hydrochloric acid and dioxin.

What is the OSHA standard for air quality?

OSHA does not have a general IAQ standard, but does provide guidelines addressing the most common workplace complaints about IAQ, which are typically related to temperature, humidity, lack of outside air ventilation, or smoking.

What size should my plenum be?

2.5 times the width of the connecting supply trunk is the width of the entrance opening. The opening width may vary from 2 to 3 times the box plenum width. The preferred box length is two times the width, but may vary from one to three times the width.

How does a plenum differ from a duct?

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 considered a plenum?

Simply stated, the NEC defines a plenum area as, “a compartment or chamber to which one or more air ducts are connected and that forms part of the air distribution system.” It also references, “the space over a hung ceiling used for environmental air-handling purposes,” and, “areas beneath raised floors for information …

What makes a ceiling plenum rated?

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 size plenum do I need for a 5-ton unit?

For 5-ton HVAC systems, an additional 6″ plenum on the bottom or the side of the furnace is super important.

What makes something plenum rated?

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

What is the most current ASHRAE standard?

The standard was renamed ASHRAE 90.1 in 2001. It has since been updated in 2004, 2007, 2010, 2013, 2016, and 2019 to reflect newer and more efficient technologies.

How does OSHA define indoors?

It can include temperature, humidity, lack of outside air (poor ventilation), mold from water damage, or exposure to other chemicals. Currently, OSHA has no indoor air quality (IAQ) standards but it does provide guidelines about the most common IAQ workplace complaints.