Fan Coil Units choose how much heating or cooling energy to produce using Proportional Integral Control.

As temperature gets further from setpoint, the fan works harder. This is the Proportional.

If the temperature is not getting close to setpoint after a time, the fan works harder. This is the Integral.

Deadband is the range around the setpoint where no heating or cooling occurs.

The balance of Proportional, Integral and Deadband is very important to comfort.

We analyse every temperature complaint, correlate it with the data at that particular time, whilst assessing the condition of the FCUs. This has given us an excellent understanding of how to set up a control system to be comfortable.