Sheet Metal Duct with Ductwrap
At Ken Adams Mechanical, we use a minimum 26 gauge thick sheet metal to custom make our duct work and wrap it with an insulation duct wrap. We don't use lighter guage sheet metal, because it eliminates banging in the duct work when the furnace starts up and shuts down. WE DO NOT USE FIBERGLASS DUCTWORK, because of the exposure to fiberglass particles getting into the air stream of the home. This is why our company uses sheet metal duct work and wraps the outside of the sheet metal box with insulation duct wrap, so there is no insulation particles in the air stream of the home.
Ducts are integral parts of ventilation systems, including heating and air conditioning. They are the pathways for airflow and are important for indoor air quality. Ducts are usually not visible, being inside walls and ceilings, connected to furnaces and central air conditioning units. Sheet metal ducts are made from galvanized steel sheet metal. There are many kinds, sizes and shapes of sheet metal ducts, but some common duct pieces are plenums, dampers, duct sleeves, roof curbs, and squares to rounds.
Ducts are integral parts of ventilation systems, including heating and air conditioning. They are the pathways for airflow and are important for indoor air quality. Ducts are usually not visible, being inside walls and ceilings, connected to furnaces and central air conditioning units. Sheet metal ducts are made from galvanized steel sheet metal. There are many kinds, sizes and shapes of sheet metal ducts, but some common duct pieces are plenums, dampers, duct sleeves, roof curbs, and squares to rounds.
Spiral Duct
Spiral duct serves as an alternative to traditional square or rectangular ductwork in heating, cooling and ventilation, or HVAC systems. This product consists of sheet metal formed into a round or oval shape, with raised seams locking adjoining sections together. The raised seams on the exterior surface of spiral duct give it an attractive finish, making it the ductwork of choice for buildings with exposed ceilings. Spiral duct can be painted.
Takeoffs and Flex Ducting
Flexible ducts, known as flex, have a variety of configurations, but for HVAC applications, they are typically flexible plastic over a metal wire coil to make round, flexible duct. A protective layer surrounds the insulation, and is usually composed of polyethylene or metalised PET. Flexible duct is very convenient for attaching supply air outlets to the rigid ductwork. However, the pressure loss through flex is higher than for most other types of ducts. As such, designers and installers attempt to keep their installed lengths (runs) short, e.g., less than 15 feet or so, and to minimize turns. Kinks in flex must be avoided. Some flexible duct markets prefer to avoid using flexible duct on the return air portions of HVAC systems, however flexible duct can tolerate moderate negative pressures - the UL181 test requires a negative pressure of 200 Pa.
Studies have shown that heating and cooling systems can lose up to 30% of their efficiency due to leaks in the duct work.
Studies have shown that heating and cooling systems can lose up to 30% of their efficiency due to leaks in the duct work.
Fabrication
This is where the ideas on paper begin to take shape. A fabrication list is created and shop personnel build the ducting and fittings. Poorly designed, fabricated, or badly sealed ductwork reduces the system's efficiency by as much as 40%, costing the homeowner money and creating a drafty, uncomfortable home. Well sealed ducting begins in the shop, and continues through the installation. Rectangular tees, ells, take-offs, reducers should be rounded for best air flow. Square fittings of any sort in a duct system inhibit air flow.
