Tech Corner: Air Balancing

In virtually all condominiums, fresh air is introduced into the building from the outside through one or more main air handlers, typically located on the roof or in the basement of the building.

The fresh air is air-conditioned at the central source and is then ducted to individual floors terminating at a grille or supply vent located in the hallway.

The typical supply vent will have one or more components. In all cases, the vent will include a directional louver, designed to direct the air down the hallways in a horizontal stream. On the majority of condominiums built within the last 25 years, a set of balancing dampers will be found immediately behind the directional louvers. There may also be a fire damper located behind the balancing dampers, designed to close on a rise in temperature (using gravity or a spring loaded arrangement held in the open position by a fusible link). The fusible link is simply two pieces of metal that are fused together with a metal that has a low melting point. The fire dampers may also be equipped with a damper actuator or motor that is engaged when the fire alarm system sends a signal to the actuators or motors.

Since the air going to individual floors comes from central air handlers, it is necessary to balance the amount of air that is delivered to each floor.

The balancing dampers are equipped with an adjustment screw to control the amount of air delivered to the floor.  Specialized companies provide these air balancing services. Using a measurement device called a velometer, the technician can check the speed of the air coming out of the vent and using a calculation based on the size of the vent can determine the volume of air delivered in litres per second (l/s) or cubic feet per minute (CFM).

Fresh air is used to pressurize the building (to prevent infiltration of outdoor air through the building envelope). It is also used to ‘make up’ for air that is exhausted from the building (bathroom and kitchen exhaust) and to provide fresh air for respiration.

Provident Energy recommends air balancing every two to three years.

~~ Dave Muffitt, Operations Manager