Abstract: A monitoring apparatus for alerting an operator to the need to change a temperature control system filter includes a mechanism for selecting and setting a primary period of filter use to assure replacement before the filter becomes clogged; a mechanism for counting out the selected primary period; a mechanism for activating a signalling device to signal the operator to replace the filter, absent replacement of the filter; a mechanism for sensing replacement of the filter; a mechanism for resetting the mechanism for counting to begin the counting out the selected primary period again upon replacement of the filter; a mechanism for counting out a secondary period measured from the end of the primary period; a mechanism for shutting down the system at the end of the secondary period absent replacement of the filter; and a mechanism for detecting a fire within the building. The apparatus preferably additionally includes a mechanism for shutting down the temperature control system upon detection of a fire.

Abstract: A monitoring apparatus for alerting an operator to the need to change a temperature control system filter includes a mechanism for selecting and setting a primary period of filter use to assure replacement before the filter becomes clogged; a mechanism for counting out the selected primary period; a mechanism for activating a signalling device to signal the operator to replace the filter, absent replacement of the filter; a mechanism for sensing replacement of the filter; and a mechanism for resetting the mechanism for counting to begin the counting out the selected primary period again upon replacement of the filter. The apparatus preferably additionally includes a mechanism for counting out a secondary period measured from the end of the primary period; and a mechanism for shutting down the system at the end of the secondary period absent replacement of the filter.