Extended Plenum Duct System

December 18, 2023 Post a Comment

Extended plenum duct system

Extended plenum system The extended plenum duct system (see Figure 2 on the next page) generally consists of one or two box- like pieces of ductwork extending from the main plenum at the indoor unit. This extended plenum has the same dimensions (height and width) from the starting collar to the end of the run.

What is a reducing extended plenum system?

6.2. Reducing Trunk System. A reducing plenum system uses a trunk reduction periodically to maintain a more uniform pressure and air velocity in the trunk, which improves air flow in branches and run outs closer to the air handler.

What is the difference between duct and plenum?

A plenum is an air distribution box designed for forced-air systems on residential homes and commercial businesses. It is part of the ductwork, but far different than an air duct as these important boxes handle air as it enters the ducts and helps to recirculate it within a system.

Is a plenum necessary in HVAC?

Heating, ventilation and cooling (HVAC) systems consist of many different components, including plenum boxes. Located in the duct work – right before the air handler or furnace – they play an important role in warming and cooling your home's interior.

What is the main drawback of extended plenum system?

The main drawback of the extended plenum system is that the velocity of the air is lower as the air reaches the last takeoffs on the extended plenum.

What is the purpose of the plenum system?

A plenum in heating, ventilation, and air conditioning (HVAC) systems is a box that connects to the HVAC system. It has a critical function and that is to bring in, distribute, and remove air. Each HVAC system typically uses two plenum boxes: a supply plenum and a return plenum.

Is it better to undersize or oversize ductwork?

It's better to be a little undersized than oversized, You'll get a little longer run time, but it's better than shortcycling.

Does reducing duct size increase pressure?

If your ducts are too small to accommodate the air flowing through them, the pressure increases and backs up in the system. This causes resistance for the blower fan, reducing your HVAC system's efficiency and longevity.

Does duct length affect cfm?

Longer ducts can increase the size of the air handler needed to supply the same cubic feet per minute (cfm), or the HVAC system may not be able to supply the designed cfm to all locations.

Why is it called a plenum?

The term "plenum" was coined in the 1670s, derived from Latin adjective plenus ("filled, full"). The usage originates from classical theories of physics and the notion that "nature abhors a vacuum".

What does the plenum connect to?

The supply plenum is an air distribution box. It's attached directly to the supply outlet of the HVAC equipment–that is, the outlet that releases chilled or heated air into your home. The air ducts that distribute the air into the individual rooms of your living space all connect to this plenum.

Do I need a plenum?

Plenum areas are more common in commercial buildings. However, if your house does happen to have a plenum airspace or you need to run cables through an air duct, then plenum-rated cable is required.

How large of a plenum do I need?

A standard sized plenum is 16 x 20. It would be the most readily available without paying extra for a custom sized plenum. I'd make the plenum long enough to keep any runs from terminating a good foot or two from the end cap and long enough that the first take offs don't take place within 4' to 6' of the air handler.

How many CFM do I need for 500 square feet?

Room Size:	CFM (At 2 ACH)
How many CFM for a 300 sq ft room?	80 CFM
How many CFM for a 400 sq ft room?	107 CFM
How many CFM for a 500 sq ft room?	133 CFM
How many CFM for a 600 sq ft room?	160 CFM

What are the two reasons for using a reducing plenum?

One reason for using a reducing plenum system is to keep	D. both A and C
The reason for using a reducing extended plenum system is to	Maintain a more even pressure throughout the entire length of the trunk duct

How far can you run duct work?

If you choose well, you can be at 10 or 20 feet of effective length. If you choose that smooth mitered elbow, however, you end up with 75 feet.

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.

How far apart should air ducts be?

It requires about 24′ or two feet to do this. This is the 'Two-Foot Rule?. Ideally, you should allow at least 24′ between takeoffs and at the end of any duct run.

Where is plenum required?

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. This qualifies this ceiling as a plenum ceiling, and all the cables that go through that ceiling must be plenum rated.

Is plenum better than riser?

Juxtaposing the differences between riser and plenum cable, you'll find that the standout difference is the fire resistance of their jackets. Since plenum jackets are manufactured with a greater fire resistance, they promote a lower risk for an electrical fire than riser cables, therefore more expensive.