A typical HVAC system consists of a heating unit, an air conditioning unit and the ventilation fan or blower at the air handler unit. A thermostat is used to control the conditioning of the air in a desired space by sending control signals to the HVAC furnace or heater, the HVAC air conditioning and the HVAC blower or ventilation fan housed in a PCB located at the air handler unit. The HVAC fan controller typically operates the ventilation fan for 0 to 90 seconds after the furnace or air conditional compressor cycles off.
Studies show that even after this automatic 90 second extension, the furnace surface / air conditioner cooling coil still has latent energy left over. This wasted energy is not delivered to the desired space when the ventilation fan stops blowing.
HVAC systems need a secondary controller (H.E.R.S. Microprocessor) for recovery of remaining heating and/or cooling capacity and optimum HVAC equipment efficiency.
In systems where the air conditioning compressor runs continuously due to extreme outside temperatures, water will still condense onto the cooling coils. This water can be made to evaporate away and release additional latent cooling energy. The H.E.R.S. Microprocessor makes use of the condensation’s latent cooling capacity by leaving the fan running over the wet cooling coils -- pushing the air cooled by evaporation into the desired space.