Variable frequency constant temperature and humidity air-conditioning units are applied to air-conditioned rooms with accuracy Δt=±1℃ and Δφ=10%. In summer, the unit's ability to control humidity is low, so the adjustment of the unit's cooling capacity is usually only two or three steps. Therefore, it is only suitable for air-conditioned rooms with small changes in humidity load. If the air-conditioned room does not need high humidity control, the unit can be used in occasions with high temperature control requirements (e.g. ±0.5℃). However, if the frequency conversion constant temperature and humidity air-conditioning unit adopts frequency conversion to control the compressor speed, the humidity control accuracy can reach ±2%.
The constant air volume all-air system constant temperature and humidity air-conditioning system with chilled water as the cooling medium adopts the reheat system. In summer, the amount of reheat is adjusted to control the temperature, and the cooling amount of air-cooled equipment is adjusted to control the humidity. Air cooling equipment, such as surface cooler systems, is suitable for occasions where humidity does not vary much. Where annual humidity variations are large or humidity control accuracy is high, thermal humidity treatment equipment should use water spray chambers. All water spray chambers are open. Chilled water systems may be open when the chilled water system is used primarily for water spray chamber equipment; closed systems should be preferred when the system has spray chambers and surface coolers, fan coils and other equipment.