3563 -- Laboratory Tests of the Nonlinearity of Outdoor Air Percentage as a Function of Damper Position and Induced Inlet Pressure PDF

Describes testing in a HVAC laboratory of the effects of damper position and inlet pressure on the ratio of outside to total supply air. States it was found that the ratio varies non-linearly with the damper position at low outdoor air flows. With induced pressure at the inlet to the main air-handling unit (simulating a windy outdoor air condition), significantly more outdoor air was taken in than the damper position might suggest. The relationship between flow and damper actuator signal or position is key to the proper control of the outside air damper.

KEYWORDS: Laboratory testing, outdoor air, dampers, air inlets, air flow, supply air, testing, pressure, winds, controls