Abstract: The present invention relates to a removable battery system for a smoke detector having a low battery detection circuitry and an audible alarm. The system includes a pair of battery receivers each adapted to receive a battery therein and being electrically coupled to the low battery detection circuitry and the audible alarm wherein at least one of the batteries provides constant power to the low battery detection circuitry and the audible alarm. The system further includes a cover that is selectively movable to provide access to the battery receivers and a locking mechanism coupled to the pair of battery receivers wherein upon failure of one of the batteries received in the pair of battery receivers that provides constant power to the low battery detection circuitry and the audible alarm, the low battery detection circuitry sounds the audible alarm and selectively activates the locking mechanism to prohibit movement of the cover.

Abstract: Multiple methods of supplying conditioned air to a room and components therefor are provided. A dual plenum system has a supply plenum for delivering supply air to the room and a return plenum for returning room air to an air handling unit. Conduits are provided to permit passage of the return air through the supply plenum without breaching the integrity of the supply plenum. Modular units permit a user to customize the supply and return apparatuses. A terminal unit having a controllable damper blade can be applied to a diffuser to permit the unit to be convertible between a constant volume unit and a variable volume unit. A thermostat generates signals that open and close the damper blade at determined intervals.