SELF CONTAINED HEATING/COOLING ROOF TOP UNIT WITH TWO-STAGE RELIEF HOOD

摘要

A self-contained air unit for installation on a roof top of a building has a pressure relief opening that is independent of the air circulation system of the unit. The air circulation system has a first blower and the pressure relief opening has a damper system that connects the pressure relief opening to ambient air through two passages. One of the passages contains a second blower to exhaust air from the air circulation system and from the independent pressure relief opening simultaneously. A two-stage pressure relief hood is provided for use with a self-contained air unit.