Method and apparatus for optimizing latent capacity of a variable speed compressor system

A method of optimizing latent capacity of an HVAC system, the method comprising:

• measuring, using a controller, a speed of a variable-speed compressor;
• calculating, using the controller, a normal cooling CFM from the measured speed of the variable-speed compressor;
• measuring, using the controller, a speed of a variable-speed circulation fan;
• determining if the speed of the variable-speed circulation fan exceeds the normal cooling CFM;
• responsive to a determination that a speed of the variable-speed circulation fan exceeds the normal cooling CFM, determining if the variable-speed circulation fan is operating at a minimum operating speed below which the variable-speed circulation fan becomes unstable;
• and
• responsive to a determination that the variable-speed circulation fan is operating at the minimum operating speed, increasing, using the controller, a speed of the variable-speed compressor.

A heating, ventilation, and air conditioning (HVAC) system comprising:

• an evaporator coil;
• a metering device fluidly coupled to the evaporator coil;
• a variable-speed circulation fan for circulating air around the evaporator coil;
• a condenser coil fluidly coupled to the metering device;
• a variable-speed compressor fluidly coupled to the condenser coil and the evaporator coil;
• a controller operatively coupled to the variable-speed compressor and the variable-speed circulation fan;
• and
• wherein the controller is configured to:
• measure a speed of the variable-speed compressor;
• calculate a normal cooling CFM;
• measure a speed of the variable-speed circulation fan;
• determine if the speed of the variable-speed circulation fan exceeds the normal cooling CFM;
• responsive to a determination that the speed of the variable-speed circulation fan exceeds the normal cooling CFM, determine if the variable-speed circulation fan is operating at a minimum operating speed below which the variable-speed circulation fan becomes unstable;
• and
• responsive to a determination that the variable-speed circulation fan is operating at the minimum operating speed, increase a speed of the variable-speed compressor.