The control has four user adjustable set points: DCV start control set point, DCV maximum control set point, minimum damper position, and DCV maximum damper position.
WATERSIDE ECONOMIZER — The WSHP Open control- ler has the capability of providing modulating or
•SAT reading is available.
•LWT reading is available.
•If occupied, the SPT is greater than the occupied cooling set point or less than the occupied heating set point and the condenser water is suitable.
•Space temperature reading is valid.
•If unoccupied, the SPT is greater than the unoccupied cooling set point or less than the unoccupied heating set point and the condenser water is suitable.
Modulating Water Economizer Control — The control has the capability to modulate a water valve to control condenser water flowing through a coil on the entering air side of the unit.
Cooling — The purpose is to provide an economizer cooling function by using the water loop when the entering water loop temperature is suitable (at least 5° F below space temperature). If the water loop conditions are suitable, then the valve will modulate open as required to maintain a
Heating — Additionally, the control will modulate the water valve should the entering water loop temperature be suitable for heating (at least 5° F above space temperature) and heat is required. The valve will be controlled in a similar manner ex- cept to satisfy the heating requirement. Should the economizer coil capacity alone be insufficient to satisfy the space load con- ditions for more than 5 minutes, then the compressor will be started to satisfy the load. Should the SAT approach the maxi- mum heating SAT limit, the economizer valve will modulate closed during compressor operation.
Cooling — The purpose is to provide a cooling economizer function directly from the condenser water loop when the en- tering water loop temperature is suitable (at least 5° F below space temperature). If the optional coil is provided and the wa- ter loop conditions are suitable, then the valve will open to provide cooling to the space when required. Should the capacity be insufficient for a period greater than 5 minutes, or should a high humidity condition occur, then the compressor will be started to satisfy the load. Should the SAT reach the minimum cooling SAT limit, the economizer valve will close during compressor operation.
Heating — Additionally, the economizer control will open the water valve should the entering water loop temperature be suit- able for heating (at least 5° F above space temperature) and heat is required. The valve will be controlled in a similar
manner except to satisfy the heating requirement. Should the coil capacity be insufficient to satisfy the space load for more than 5 minutes, then the compressor will be started to satisfy the load. Should the SAT reach the maximum heating SAT limit, the economizer valve will close during compressor oper- ation.
DEMAND LIMIT — The WSHP Open controller has the ability to accept three levels of demand limit from the network. In response to a demand limit, the unit will decrease its heating set point and increase its cooling set point to widen the range in order to immediately lower the electrical demand. The amount of temperature adjustment in response is user adjustable for both heating and cooling and for each demand level. The re- sponse to a particular demand level may also be set to zero.
CONDENSER WATER LINKAGE — The control pro- vides optimized water loop operation using an universal con- troller (UC) open loop controller. Loop pump operation is auto- matically controlled by WSHP equipment occupancy sched- ules, unoccupied demand and tenant override conditions. Positive pump status feedback prevents nuisance fault trips. The condenser water linkage operates when a request for con- denser water pump operation is sent from each WSHP to the loop controller. This request is generated whenever any WSHP is scheduled to be occupied, is starting during optimal start (for
SYSTEM TEST
System testing provides the ability to check the control operation. The control enters a
Test Mode — To enter Test mode on Complete C or De- luxe D controls, cycle the fan 3 times within 60 seconds. The LED
NOTE: The Deluxe D control has a flashing code and alarm relay cycling code that will both have the same numerical label. For example, flashing code 1 will have an alarm relay cycling code 1. Code 1 indicates the control has not faulted since the last power off to power on sequence.
Retry Mode — In Retry mode, the status LED will start to flash slowly to signal that the control is trying to recover from an input fault. The control will stage off the outputs and try to again satisfy the thermostat used to terminal Y. Once the ther- mostat input calls are satisfied, the control will continue normal operation.
NOTE: If 3 consecutive faults occur without satisfying the thermostat input call to terminal Y, the control will go into lockout mode. The last fault causing the lockout is stored in memory and can be viewed by entering Test mode.
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