Runtime sensor for small forced air handling units

摘要

Herein are disclosed devices and methods that can be used to provide an indication of the need to change a filter in a small forced air handling unit, based on the actual operating time (runtime) of the unit. The methods rely on the use of at least one vibration sensor that is placed in contact with a surface of an exterior component of the air handling unit and that can determine whether the unit is operating by sensing vibrations of the surface caused by operation of the unit.