Ducting In HVAC...
If your HVAC equipment is the heart of your home, then the ducts make up its circulatory system.
Air ducts are used to distribute air through out a building, or to exhaust air outside of a building.The most common are:Sheet metal,Fiberglass lined,Fiberboard, and Flex-line air ducts.
Ducts are classified based on the load on duct due to air pressure and turbulence.The classification varies from application to application, such as for Residences,Commercial systems,Industrial systems etc. For example, one such classification is given below:
Low pressure systems: Velocity = 10 m/s,static pressure = 5 cm H2O (g)
Medium pressure systems: Velocity = 10 m/s, static pressure = 15 cm H2O (g)
High pressure systems: Velocity > 10 m/s, static pressure 15
Faulty Electrical Connections
Another prevalent reason why Air Conditioners fail to perform is because the Outdoor unit isn't getting enough power to operate to its rated capacity. This could be due to Faulty wiring, a result of electrical overload, a short circuit or because simply the fuse has blown up.
Types Of Ducts
- Flexible Ductwork
Flexible ducts are typically tube-shaped, made of a wire coil covered with a bendable, durable plastic, and surrounded by insulation. This kind of ducting is best in tricky spaces where rigid ducts are just not possible to install, or used to attach non-flexible ductwork to an air supply outlet.
- Rigid Ductwork
They come in a variety of materials and sizes, and can be either cylindrical or rectangular. They are also often insulated. They are hardy, enduring, and reliable.The most common types of rigid ductwork are:
- Sheet Metal Air Ducts
The most common type of ridged air duct is constructed of galvanized steel or aluminum.They may be round, rectangular, or in the form of a spiral oval. Sheet metal air ducts are the most durable type of air duct construction, and because their non-porous surface, are the least likely to have mold or biological growth.
- Fiberglass Lined Air Ducts
Some sheet metal air ducts air ducts are lined with an external or internal fiberglass duct liner. Fiberglass lining is used to insulate air ducts from heat loss or to avoid condensation in cases where the supply air is very cold, or there is a high ambient humidity in the plenum. Fiberglass lining also provides sound attenuation, reducing the noise of the HVAC system.
- Fiberboard Air Ducts
Fiberboard air ducts are constructed with boards of compressed resin bonded inorganic glass fibers. They have a foil face on the outside that serves as the air barrier and water vapor retarder. The interior of fiberboard air duct is sealed to prevent fiberglass fibers from entering the air stream. Fiberboard air duct also provide acoustical and thermal benefits, and are typically the most inexpensive air duct systems to install.
- Flexible Air Ducts
Flexible air ducts are constructed with a spring steel wire helix, encapsulated in a 2-ply, polymer plastic. Flexible air ducts are inexpensive, lightweight, and easy to install. It is important that the lengths of the flexible air ducts be kept as short as possible as the length of flexible, and numbers bends within the flexible greatly effects system performance.
- Necessary of Ducting
Ductwork channels conditioned air to vents, takes return air back into the system and transports exhaust air and waste heat to the exterior of your home. Ducts serve a triple purpose: They carry warmth in winter, hold cool air in summer and provide ventilation for better indoor air quality throughout the year. Because they're in use almost every day, your ducts need occasional maintenance to improve the longevity of your heating and air conditioning equipment.
