Hollow core door apparatus for preventing the build up of pressure in a room having a register through which air flows into the room and the door includes an inside door skin and an outside door skin, and the door skins includes openings through which air flows and a center panel between the skins and spaced part from the skins. The center panel has an outer perimeter greater than the inner perimeter of the openings. The center panel is spaced apart from the skins, and also from the adjacent stiles and rails. A chamber is formed about the panel and between the adjacent stiles and rails and the openings in the skins. Air flow from the room is through the opening in the inside skin into the chamber, around the outer periphery of the panel, and outwardly through the opening in the outside skin in a non-linear manner.

Hollow core door apparatus for preventing the build up of pressure in a room having a register through which air flows into the room and the door includes an inside door skin and an outer door skin, and the door skins includes openings through which air flows and panels disposed in the openings to define the amount of air flowing through the openings in the skins. The door also includes at least a single fixed panel and a movable panel, both of which panels include openings through which air flows when the openings in the panels are aligned and which air flow is restricted when the openings are misaligned. The inside and outside panels have peripheral openings defined between the openings in the skins and the panels disposed in the openings and which peripheral openings define areas at least as great as the area of the openings in the fixed and movable panels, and the openings in the fixed and movable panels are offset from the peripheral openings to provide for a non-linear flow of air through the door to prevent the build up of pressure in the room and to restrict the non-linear air flow through the door when the openings in the fixed and movable panels are misaligned. An embodiment combining a noxious gas absorbent material with the pressure build up prevention capability is also illustrated.

A control system, comprising one or more smoke sensors, each configured to measure a level of smoke at a location within a building and to output a smoke level signal based at least in part upon the measured level of smoke. A controller configured to receive the smoke level signals and to control an operation of one or more energy recovery ventilation systems in a first mode of operation to recover energy when the smoke level signal is below a predetermined value and in a second mode of operation to evacuate smoke when the smoke level signal is above the predetermined value.

A regulating flap reduction gear for an electrically driven regulating flap for regulating a gas or liquid volume flow includes two parallel bearing plates between which gear parts are rotatably arranged. A plurality of spacers keep the two bearing plates at a distance from one another. The plurality of spacers are designed as tabs of one, first bearing plate, which are bent by 90° from the plane of the first bearing plate and have at least one lateral projection. The tabs are inserted with their free tab ends into plug-in openings of the other second bearing plate until their at least one lateral projection rests against the second bearing plate.

A regulating flap reduction gear for an electrically driven regulating flap for regulating a gas or liquid volume flow includes two parallel bearing plates between which gear parts are rotatably arranged. A plurality of spacers keep the two bearing plates at a distance from one another. The plurality of spacers are designed as tabs of one, first bearing plate, which are bent by 90° from the plane of the first bearing plate and have at least one lateral projection. The tabs are inserted with their free tab ends into plug-in openings of the other second bearing plate until their at least one lateral projection rests against the second bearing plate.

An access control system receives a trigger command for controlling a ventilation system; determines that the trigger command includes a lock trigger to hold an entrance door in a closed position; and induces a locking differential air pressure between opposite sides of the entrance door in response to the lock trigger, where the locking differential air pressure is sufficient to bias the entrance door to contact or to increase contact with a door frame in the closed position. The access control system may also determine that the trigger command includes an open assist trigger to ease an opening of the entrance door; and may induce an opening differential air pressure between the opposite sides of the entrance door in response to the open assist trigger, where the opening differential air pressure is sufficient to bias the entrance door to reduce contact with the door frame in the closed position.

An access control system receives a trigger command for controlling a ventilation system; determines that the trigger command includes a lock trigger to hold an entrance door in a closed position; and induces a locking differential air pressure between opposite sides of the entrance door in response to the lock trigger, where the locking differential air pressure is sufficient to bias the entrance door to contact or to increase contact with a door frame in the closed position. The access control system may also determine that the trigger command includes an open assist trigger to ease an opening of the entrance door; and may induce an opening differential air pressure between the opposite sides of the entrance door in response to the open assist trigger, where the opening differential air pressure is sufficient to bias the entrance door to reduce contact with the door frame in the closed position.

A fire damper for an air distribution system includes a body defining a flow path and a closure means adapted to close the flow path when a temperature within the flow path exceeds a predetermined maximum temperature. A first flange is fixed to the body and a mounting means comprising a second flange is slidably engageable with and removable from the body. The mounting means comprises securing means for securing the mounting means to the body such that a building element through which the fire damper extends, in use, can be clamped between the first and second flanges. A flexible insulating sleeve configured for use with a fire damper, and a method of installing a fire damper, are also disclosed.

A fire damper for an air distribution system includes a body defining a flow path and a closure means adapted to close the flow path when a temperature within the flow path exceeds a predetermined maximum temperature. A first flange is fixed to the body and a mounting means comprising a second flange is slidably engageable with and removable from the body. The mounting means comprises securing means for securing the mounting means to the body such that a building element through which the fire damper extends, in use, can be clamped between the first and second flanges. A flexible insulating sleeve configured for use with a fire damper, and a method of installing a fire damper, are also disclosed.

A damper of a heating, ventilation, and/or air conditioning (HVAC) system includes a crank configured to rotate about an axis of a shaft relative to a support, a reset arm configured to rotate about the axis of the shaft relative to the support, a spring coupled to the crank and the reset arm, and a fuse link configured to be coupled to the reset arm and the support in a set configuration and to release the reset arm from the support in response to a temperature exceeding a threshold temperature. The crank and the reset arm are configured to rotate away from the support in a first circumferential direction toward a closed configuration in response to the fuse link releasing the reset arm from the support. A spring force of the spring is configured to increase to enable the reset arm to rotate in a second circumferential direction opposite to the first circumferential direction beyond the set configuration and into a reset configuration.