What are the 4 types of duct systems

The four types of duct systems most commonly used in residential and commercial buildings are the top-down or floor/ceiling system, the upflow system, the re-circulating system, and the supply/return system. Each of these systems offers different advantages and features that make them suitable for a range of applications.

1. Top-Down or Floor/Ceiling System: This type of ducting incorporates a thin steel or aluminum sheet mounted to either side of an attic joist or wall studs. Attached to each sheet is another thin metal covering called an infeed baffle. The infeed baffle directs air into slots cut into each side of the ductwork which brings conditioned air from either an upper floor or lower ceiling down to living areas on other floors.

2. Upflow System: The upflow system uses a large metal box with holes near its base, typically located under a window sill. Warm air is pulled down through the duct from another level, usually from higher floors such as a lofted bedroom space, using natural convection currents created by differences in the density and temperature between intake and existing room air temperatures.

3. Re-Circulating System: The re-circulating system utilizes short metal boxes known as plenums which attach directly onto an existing furnace blower seresto collar cats motor to form a large fan that pulls air up through the house’s existing heating ducts within attics or walls and returns them back through outlets in some form after taking heat off it via an internal fan coil unit attached before them making it more efficient overall compared to other traditional duct designs since there are no long runs involved with this one with improved control over temperature throughout areas reducing loss while raising efficiency rating noticeably longer than normal units due too less pressure losses it provides dampers mounted inside each main trunk line too improve comfort levels even further getting cooled off slowly instead .

4. Supply/Return System: Finally, last but not least – supply & return systems – here we have rectangular panels made out of sheet metal attached together interconnecting one room from another along with outlets either featured at elbow joints specially designed tee pieces similar to what we’ve seen so far but utilizes loose fittings allowing faster installation speeds often found seen most commonly through homes where running time for installation matters greatly in order for customers have working home ac again quicker without having problems when cold winter months start to arrive this also works well at preventing any sound transmissions depending on media installed interiorly; insulation being highly recommended here as well if possible due lack space normally limitations presented inside closeness areas such basements tight crawl spaces etc reducing noise emissions annoying non family members while increasing operation efficiency movement related costs running cost wise overall helping customer save plenty money depending those areas.*

Introduction to duct systems

A duct system is the network of channels that distributes the heated or cooled air from a central heating and cooling system to other parts of a building. Duct systems are usually made of flexible materials such as metal, PVC, or fiberglass and run through ceilings, walls and floors. The four different types of duct systems include: single-duct, dual-duct, two-pipe fan-coil and variable air volume (VAV) systems.

Single duct systems use one pipe to distribute HVAC air throughout the building, with temperature control valves in each room regulating airflow separately. Dual-duct systems divide cold and hot air into separate pipes so airflow can be easily adjusted according to changing temperature needs in each room. Two-pipe fan-coil systems bring conditioned air directly to each room via dedicated pipes connected to individual fans in rooms, while VAV systems adjust the amount of conditioned air depending on occupancy levels in each space.

No matter what type of duct system you’re using, proper installation and maintenance is essential for optimal performance and efficiency. Make sure you’re following manufacturers’ instructions during installation to guarantee safety and quality results over time.

Overview of the 4 types of duct systems

The four different types of duct systems are spiral ducts, rectangular ducts, round ducts, and flexible duct systems.

Spiral duct systems use special dies to form round tubes that join together in an overlapping configuration. This type of system has the capability of withstanding large temperature fluctuations.

Rectangular ducts are easier to connect and allow for efficient installation as well as lower costs than other types of ducts, making it the most common choice for residential applications.

Round ducts require less air pressure than other types of systems and can be used for both commercial and residential applications. Round ducts tend to be quieter but also take up more space than other types due to their larger surface area.

Flexible duct systems are easy to install and are typically used in areas that don’t require frequent changes in direction or tight bends. They also reduce sound transmission which makes them ideal for spaces that need a quiet environment.

All these types of duct systems have advantages depending on the application, cost constraints, code requirements, and environmental factors.


Single-duct systems aren’t quite as efficient as other types of duct systems, but they are the most common. With a single-duct system, all the conditioned air is supplied through one duct and routed around your home or building. The temperature of the air is controlled by a thermostat and this system uses a blower to move air in and out of the ducts.

Advantages of single-duct systems include their affordability, ease of installation, and ability to control multiple zones in one home or building. Disadvantages include poorer quality air movement and less energy efficiency than other types of HVAC systems.


The dual-duct system is one of four types of duct systems used in HVAC systems. Dual-duct systems have two separate supply and return ducts installed for temperature control. In other words, each zone or section of the building will have its own supply and return air ducts. This allows the air conditioner to provide cooling or heating independently to different zones based on need.

One drawback to a dual-duct system is that it can become complex and costly if there are many zones that need heating or cooling. But the benefits include superior comfort since the temperature can be specifically controlled for each zone, improved efficiency since energy isn’t wasted on areas where it isn’t needed, and increased safety since volatile or hazardous fumes can be quickly vented away from occupants in specific areas if necessary.