Abstract: A programmable timing device for use in combination with an existing thermostat housing is set forth wherein the apparatus effects actuation selectively or in combination of an audible and visual display to alert an individual to a need in maintenance of an associated furnace air filter. The apparatus may be secured to a wall surface or optionally, adhesively secured to the existing thermostat housing by means of a mounting bracket. The mounting bracket is provided with break-away orthogonally oriented grooves to accommodate the housing of the timing apparatus in regions of limited support wall surface area to accommodate the entire mounting bracket.