The Aprilaire 8191 Ventilator with Dehumidification brings in fresh air to meet ventilation needs while removing the high humidity that comes in with the outdoor air. Fresh air is brought in when the air conditioning is running to allow the cooling equipment to remove humidity from the air. If ventilation needs cannot be met when the air conditioning is running the Model 8191 brings in fresh air and removes the humidity with the integral dehumidification system. The desired amount of ventilation and the maximum allowable humidity level is set using the built-in control which then measures the humidity of the air to determine if dehumidification is needed. Energy savings, while meeting the ventilation need, is optimized by using high and low-temperature limits to bring in outdoor air when temperatures are more moderate.