Abstract: This invention is directed to a user-sizable filter grid and an adjustable interlocking filter frame and grid system suitable for use in heating and cooling systems. The user-sizable grid is adapted to interlock with an adjustable frame, thereby holding a filter in the grid/frame assembly, and includes at least one member extending across at least one of the length and width of the frame. The member has interlocks for engaging a flange on the frame, thereby securing the frame and grid together. Examples of different types of interlocks include indentations, pincher-like grippers and projections, with the indentations being the preferred form. In the preferred embodiment, the grid includes a plurality of horizontal and vertical members that intersect one another, with indentations being distributed along the intersecting members so that the adjustable frame may engage the interlocks while accommodating various standard filter sizes.

Abstract: An air cleaner with a smoke alarm unit for a forced air recirculating system is disclosed. The smoke alarm unit is housed within a module that fits within the frame of the air cleaner with minimal impact on the cleaning ability of the cleaner. In a preferred embodiment of the invention, a battery capacity tester and air cleaner functionality detector are included in the module. Signals from the battery tester and functionality detector are used by the smoke alarm unit to drive an alarm generator with different signals to produce distinguishable alarms for a smoke condition, low battery condition, and an air cleaner failure. A control unit may receive any of the alarm conditions to execute different control actions in the forced air system.

Abstract: An air cleaner with a smoke alarm unit for a forced air recirculating system is disclosed. The smoke alarm unit is housed within a module that fits within the frame of the air cleaner with minimal impact on the cleaning ability of the cleaner. In a preferred embodiment of the invention, a battery capacity tester and air cleaner functionality detector are included in the module. Signals from the battery tester and functionality detector are used by the smoke alarm unit to drive an alarm generator with different signals to produce distinguishable alarms for a smoke condition, low battery condition, and an air cleaner failure. A control unit may receive any of the alarm conditions to execute different control actions in the forced air system.