Low performance in fan coils or underfloor systems: organized troubleshooting instead of random adjustments

When a space is not being heated or cooled correctly, the diagnosis must follow a specific order rather than random setpoint changes.

1. Supply temperature

Check if the water is reaching the correct temperature for the specific operation.

2. Water flow

Check the circulator, filters, valves, flow meters, and any trapped air.

3. Fan coil

Check the air filter, fan, coil, and valve actuator.

4. Underfloor heating

Check loop flow rates, actuators, and supply-return temperatures.

5. Load comparison

If everything is operating correctly but the space is not comfortable, evaluate whether the terminal units have sufficient capacity for the actual heat losses of the room.