What does 'in-control' and 'out of control' fan coil of air conditioning thermostat mean?

The "in-control fan coil" and "out-of-control fan coil" mentioned in the air conditioning thermostat essentially refer to whether the thermostat controls the fan in the fan coil system. This is related to the degree of linkage between the thermostat and the fan coil unit (FCU, Fan Coil Unit), which has a significant impact on the energy saving, comfort and control strategy of the system.

I. Introduction to fan coil system:

Fan coil system is a common central air conditioning terminal equipment, and its core components include:

Fan: promotes air circulation

Coil: achieves cooling or heating through hot and cold water heat exchange

Controller (air conditioning thermostat): controls temperature setting, wind speed, switch status, etc.

II. The difference between fan coil "in-control" and "out-of -control" mode:

Project	In-control mode	Out-of-control mode
Fan Control	Thermostat controls the wind speed or switch	The fan is always running or automatically controlled by the system
Wind speed adjustment	Can be adjusted manually or automatically (high/medium/low/automatic)	Wind speed is usually fixed and does not change with temperature
Energy saving effect	Better, the fan starts and stops on demand to avoid idling	Poor, the fan may continue to run and cause energy waste
Comfort	Better, the wind speed can be adjusted intelligently according to temperature changes	Slightly lower, the wind may feel uncomfortable or hot and cold
Noise control	Quieter when the wind speed is low	Continuous operation of the fan may cause continuous noise
Typical scenarios	High-end residences, office buildings, hotels	Simple systems, public areas, old buildings

III. Differences in technical principles:

Fan coil "in-control":

Thermostat outputs wind speed control signal, usually three speeds: high, medium, low.

It can also output fan start and stop signal.

Thermostat will determine whether the room temperature reaches the set value, automatically start and stop the fan or adjust the wind speed.

Fan coil "out-of-control":

The fan is always powered on or controlled by the building central system.

Thermostat only controls the solenoid valve (adjusting the hot and cold water on and off), and cannot control the fan start and stop or wind speed.

Summary:

Fan coil "in-control": Thermostat can control the fan start and stop and wind speed adjustment, which is more energy-saving and comfortable;

Fan coil "out-of-control": Thermostat can only control the water valve, the fan is always running or controlled by the system, and the comfort and energy saving are slightly worse.