For a long time, because of the flexibility to control the air-conditioning units of the start and stop and indoor temperature, and can save the construction space and engineering cost, fan Coil (FCU) plus new air conditioning system has been a room and business methods for rent-based hotel hotels and office buildings, such as the preferred semi-centralized air conditioning system style.

The room air conditioner thermostat is the key of controlling the end device-Fan coil unit (FCU) for cooling/heat, realizing the chamber temperature control and energy saving operation. General fan coil Air conditioning thermostat is basically a separate closed-loop temperature control system, mainly by the temperature sensor, the dual-position controller, temperature setting mechanism, manual three-speed switch and hot and cold switching device composition.

The control principle is that the air conditioning thermostat according to the temperature sensor measured by the room temperature and the set value of the comparison between the two-position control signal, the control of hot and cold water circulation electric valve (two-way valves or three-way valve) switch, that is, with the cut off and open the coil pipe flow circulation, adjust the air temperature (cooling) The first generation of air conditioning thermostat is mainly electrical products, air conditioning thermostat temperature sensor using bimetal or pneumatic temperature package, through the "given temperature plate" to adjust the preload force to set the temperature, fan three-speed switch and the season switch for the splash-type mechanical switch.

This kind of air-conditioning thermostat products are generally "too coarse temperature setting", "time constant is too big", "mechanical switch easily damaged" and so on. The second generation of air-conditioning thermostat for electronic products, temperature sensors using thermistors or thermal resistance, part of the product's temperature setting and wind speed switch through the touch key and LCD screen to achieve human-computer interface, hot and cold switching automatic completion, op-amp circuit and switch circuit to achieve double-position adjustment.

This kind of intelligent air conditioning thermostat products improve the human-computer interaction interface, solve the "temperature setting of the value of the coarse" and other problems, but there are still "control accuracy is not high", "time constant large", "Operation more complex" and so on. At present, domestic and foreign manufacturers are studying and developing the third generation of intelligent room temperature thermostat, applying new control model and NC chip to realize intelligent control. Now there are domestic manufacturers to produce a smart room temperature air conditioning thermostat, and has been applied to the actual project.