Control device for HVAC fan coil units

A method of operating a control device controlling an HVAC device of a unit of a building, the HVAC device comprising at least a first coil supplied with a first working fluid and a fan, the method comprising:

• (a) determining with a sensor at a supply pipe of the first coil the temperature of the first working fluid supplied to the first coil;
• (b) if the determined temperature is above a preselected temperature, the control device operating in a heating configuration to maintain the temperature of the environment served by the control device at a target temperature, wherein the first coil is connected to a shared heating and chilling plant by the supply pipe to deliver the first working fluid with a first temperature that serves the building that contains a plurality of units that include a plurality of HVAC devices, including the unit that includes the HVAC device served by the control device;
• and
• (c) if the determined temperature is below the preselected temperature, the control device operating in a cooling configuration to maintain the temperature of the environment served by the control device at a target temperature.

A control device comprising:

• a first sensor connectable to a heating fluid supply pipe of a fan coil unit (FCU) that includes a heating coil to circulate heated working fluid and a fan to force air over the heating coil, wherein the heating fluid supply pipe is to supply the heated working fluid from a plant shared by a plurality of FCUs to the heating coil of the FCU, wherein the first sensor is to sense a first temperature of the heated working fluid in the heating fluid supply pipe;
• a second sensor connectable to a cooling fluid supply pipe of the FCU, which further includes a cooling coil to circulate chilled working fluid, wherein the cooling fluid supply pipe is to supply the chilled working fluid from the plant shared by the plurality of FCUs to the cooling coil of the FCU, wherein the second sensor is to sense a second temperature of the chilled working fluid in the cooling fluid supply pipe;
• and
• a processor connected to the first sensor and the second sensor, the processor configured to operate the FCU by controlling air flow by the fan over the heating coil or the cooling coil based on the first temperature or the second temperature, wherein:
• when the processor determines that the temperature of the heated working fluid exceeds a preset value, then the processor controls the FCU to operate in a heating mode.