Sizing and balancing air duct systems.


Equal area vs. Log-Tchebycheff.


Balancing air flow in ventilating duct systems.

The paper is concerned with the procedure for regulating or balancing a ventilation· system, so as to ensure that each outlet supplies or extracts its proper quantity. It deals with methods, organisation instrumentation and recording of results; it also discusses the accuracy required and attainable in ordinary practice. The advocated method of regulating consists of balancing the proportions of air flow at the junctions of a system, dealt with in a routine order, followed by the adjustment of the complete system to design volume by a final setting at the fan.

Tooled up for cleaning.

When do you know your ventilation ductwork needs cleaning, how do you go about it and what does hygienic mean? A new set of practical guides .. looks at addressing these issues.

Should you have the air ducts in your home cleaned?


Those wild ducts in your walls.

More than three-fifths of the households in the U.S. heat or cool their homes with ducted forced air systems, so chances are good that air ducts are lurking within your walls, floors, or ceilings. These air ducts move conditioned air to warm and cool your family. They can be a great source of comfort-but more likely they are wasting energy and costing you money. Typical duct systems lose 25 to 40 percent of the heating or cooling energy put out by the central furnace, heat pump, or air conditioner.

Compact heat exchanger integrated into air duct system.

A Japanese electronics company has developed a new type of gas-to-gas heat exchanger, called the Ductron. The heat exchanger has a simple structure composed of aluminium or stainless steel pass partition plates stacked with a gas passage (1 cm wide) between each plate, Heat exchange duct- Ductron and can be installed as part of an air duct system. It is applicable not only to HVAC systems but also to various industrial applications. The efficiency level is over 5 0%.