Hvac blower motor with speed sensor

A blower motor assembly for an HVAC system, the blower motor assembly comprising:

• an electric motor having a rotatable shaft for coupling with an air-moving device;
• a speed sensor for sensing a rotational speed of the shaft and thus the air-moving device, the speed sensor comprising:
• a magnet coupled with the shaft of the motor for rotation therewith;
• and
• a coil assembly mounted concentrically over the magnet and operable to generate an alternating signal when the magnet rotates relative to the coil, the alternating signal having an electrical characteristic that is generally proportional to the rotational speed of the shaft so that the alternating signal may be used to monitor a minimum speed of the shaft.

An HVAC system comprising:

• a heating element;
• an electric motor having a rotatable shaft coupled with a blower wheel for blowing air over the heating element;
• a speed sensor for sensing a rotational speed of the shaft and thus the blower wheel, the speed sensor comprising:
• a magnet coupled with the shaft for rotation therewith;
• a coil assembly mounted concentrically over the magnet and operable to generate an alternating signal when the magnet rotates relative to the coil, the alternating signal having an electrical characteristic that is generally proportional to the rotational speed of the magnet;
• and
• a control device integrated into an HVAC control board for receiving the alternating signal from the speed sensor and for disabling operation of the heating element when the alternating signal indicates that the rotational speed of the shaft drops below 800 RPM.