HVAC Controller controls the temperature and humidity of the air conditioning equipment. From a small air conditioner to a big air handling unit, this HVAC controller can meet each needs by just changing set points. It consists of various display standard temperature and humidity sensors. STHAV series, HVAC controller line-up of Seungil Electronics can be used for cooling/heating air conditioners and for various HVAC equipment, including thermo-hygrostat since it equipped with 5 step heating, 2 step cooling(dehumidifying), and 1 or 2 step humidifying(2 step: fan type, 1 step: evaporative/electrode type) controller. If the communication board is added, remote display control and PC monitoring functions can be provided. It is designed to accommodate free voltage usage by adopting SMPS power structure and to have string resistance to external noises.