Patent ID: 8185246

Claim:
A method of controlling an air-conditioning system of the type having a system operator, a building management system, a heat exchanger coil with a coolant fluid flowing therethrough, and a flow of air being circulated therethrough, comprising: determining if the system is in a cooling mode; determining a supply air temperature; establishing a low supply side component temperature limit; comparing said supply air temperature with said low supply side component temperature limit; responsively raising the supply side coolant fluid temperature; obtaining a coolant fluid supply temperature of a supply coolant fluid entering said coil; obtaining a coolant fluid return temperature of a return coolant fluid exiting said coil; comparing said coolant fluid supply temperature with said coolant fluid return temperature to obtain a coolant fluid delta temperature; establishing a coolant fluid delta temperature setpoint; comparing said coolant fluid delta temperature with said coolant fluid delta temperature setpoint to obtain a coolant fluid delta temperature error; providing at least one valve for controlling the flow of coolant fluid through said coil; and actuating said valve in response to said coolant fluid delta temperature error.