Abstract: A fresh air heating system includes air intake and discharge chambers, a direct-fired gas burner mounted in a burner chamber in fluid communication with intake and discharge chambers therebetween, and a bypass opening between the air intake and discharge chambers that is selectively closed by a hatch cover having a panel and a peripheral wall extending from the panel.

Abstract: A fresh air heating system includes air intake and discharge chambers, a direct-fired gas burner mounted in a burner chamber in fluid communication with intake and discharge chambers therebetween, and a bypass opening between the air intake and discharge chambers that is selectively closed by a hatch cover having a panel and a peripheral wall extending from the panel.

Abstract: A terminal unit for an air handling system and comprised of a housing having a conditioned air inlet for receiving forced conditioned air in the housing. A main outlet opening and a by-pass air outlet opening are provided in the housing. An air flow path is defined between the air inlet and the outlet openings. An air divider gate is slidingly displaceable transverse to the air flow path to deflect air entering the inlet to one or both of the outlet openings. The divider gate has an outlet obstructing rear end and an upstream deflecting face. A linkage assembly is connected to the divider gate to displace the gate across the flow path to simultaneously open one of the outlet openings and close the other, in equal proportions, as desired, while maintaining a substantially constant total outlet opening area as well as maintaining substantially constant inlet air flow conditions.

Abstract: A constant air pressure unit for an air handling system. The unit comprises a housing having an air inlet opening for admitting pressurized air into the housing. The housing has a top wall with a by-pass opening therein and a door is displaceably retained over the by-pass opening. The door has a predetermined load whereby the door is caused to lift away from the by-pass opening when the pressure of the air in the housing is equal to the pressure required to lift the load. The door load defines a maximum housing pressure. In the case where the pressure at the inlet opening starts to increase above the predetermined maximum housing pressure, the door lifts and by-passes the excess pressurized air and thus limits the inlet and housing pressures. In a corollary unit, an air outlet opening for releasing air is included. A pressurized airflow path is defined between the inlet opening and the outlet opening.