screen. The following conditions must be true for economizer operation:
•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 pro- vide 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 man- ner 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 operation.
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 |
controller (UC) open loop controller. Loop pump operation is automatically controlled by WSHP equipment occupancy schedules, 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
COMPLETE C AND DELUXE D BOARD
SYSTEM TEST
Test mode provides the ability to check the control opera- tion in a timely manner. The control enters a
Test Mode — To enter Test mode, cycle the power 3 times within 60 seconds. The LED will flash a code representing the last fault when entering the Test mode. The alarm relay will also power on and off during Test mode. See Tables 34 and 35. To exit Test mode, short the terminals for 3 seconds or cycle the power 3 times within 60 seconds.
NOTE: The flashing code and alarm relay cycling code will both have the same numerical label. For example, flashing code 1 will have an alarm relay cycling code 1. Code 1 indi- cates the control has not faulted since the last power off to power on sequence.
Table 34 — Complete C Control Current LED
Status and Alarm Relay Operations
LED STATUS | DESCRIPTION OF OPERATION | ALARM RELAY | ||||
|
|
| Normal Mode | Open | ||
| On | Normal Mode with PM Warning | Cycle (closed 5 sec., | |||
|
| open 25 sec.) | ||||
|
|
|
|
| ||
| Off | Complete C Control is | Open | |||
| Slow Flash |
| Fault Retry |
| Open | |
| Fast Flash |
| Lockout |
| Closed | |
| Slow Flash | Over/Under Voltage Shutdown | Open, (Closed after | |||
| 15 minutes) | |||||
|
|
|
|
| ||
Flashing Code 1 | Test Mode — No fault in memory | Cycling Code 1 | ||||
Flashing Code 2 | Test Mode — HP Fault in memory | Cycling Code 2 | ||||
Flashing Code 3 | Test Mode — LP Fault in memory | Cycling Code 3 | ||||
Flashing Code 4 | Test Mode — FP1 Fault in memory | Cycling Code 4 | ||||
Flashing Code 5 | Test Mode — FP2 Fault in memory | Cycling Code 5 | ||||
Flashing Code 6 | Test Mode — CO Fault in memory | Cycling Code 6 | ||||
Flashing Code 7 | Test Mode — Over/Under | Cycling Code 7 | ||||
shutdown in memory | ||||||
|
|
| ||||
Flashing Code 8 | Test Mode — PM in memory | Cycling Code 8 | ||||
Flashing Code 9 | Test Mode — FP1/FP2 | Cycling Code 9 | ||||
Swapped Fault in memory | ||||||
|
|
| ||||
|
| LEGEND |
|
| ||
CO | — Condensate Overflow | LED | — | |||
FP | — Freeze Protection | LP | — Low Pressure | |||
HP | — High Pressure | PM | — Performance Monitor |
NOTES:
1.Slow flash is 1 flash every 2 seconds.
2.Fast flash is 2 flashes every 1 second.
3.EXAMPLE: “Flashing Code 2” is represented by 2 fast flashes followed by a
46