Description of Operation
Occupancy Modes
The UVC is provided with four occupancy modes: Occupied, Standby, Unoccupied, and Bypass. The occupancy mode affects which heating and cooling temperature set points are used, affects IAF operation, and affects OAD operation. The Manual Adjust Occupancy and Networked Occupancy Sensor network variables, along with the Unoccupied and Tenant Override binary inputs, are used to determine the Effective Occupancy. The term “Don’t care” in Table 12 implies that another network variable or binary input to the left has a higher priority.
Note – The Occupancy Override Input is provided as a way for a network connection to manually force the UVC into a particular occupancy mode. The Occupancy Override Input can override the tenant override feature. For example, if the network uses the Occupancy Override Input to force the unit into unoccupied mode, then the tenant override switch does not operate as expected. Therefore, McQuay strongly recommends using the Occupancy Sensor Input to control occupancy modes over a network and only using the Occupancy Override Input if there is reason to ensure tenant override does not occur.
Table 12: Occupancy mode priority
|
|
|
| Priority result |
|
Occupancy | Occupancy | Unoccupied binary input |
| Effective |
|
| occupancy |
| |||
Override input | sensor input1 |
|
| ||
|
| output2 |
| ||
|
|
|
|
| |
Occupied | Don’t care | Don’t care |
| Occupied |
|
Unoccupied | Don’t care | Don’t care |
| Unoccupied |
|
| Occupied | Don’t care |
| Occupied |
|
Bypass | Unoccupied | Don’t care |
| Bypass |
|
Null (default) | Contacts open (Occupied) |
| Occupied |
| |
|
|
| |||
| Contacts Closed (Unoccupied) |
| Bypass |
| |
|
|
|
| ||
Standby | Don’t care | Don’t care |
| Standby |
|
| Occupied | Don’t care |
| Occupied |
|
Null (default)3 | Unoccupied | Don’t care |
| Unoccupied4 |
|
Null (default) | Contacts open (Occupied) |
| Occupied |
| |
|
|
| |||
| Contacts closed (Unoccupied) |
| Unoccupied4 |
| |
|
|
|
|
1.Network input.
2.Network output.
3.Typical operation is defined in this row of the table.
4.The tenant override switch (unit or wall sensor mounted) can be used here to force the UVC into bypass.
Occupied Mode
The occupied mode is the normal day time mode of UVC operation. During occupied mode the UVC uses the occupied heating and cooling set points, the OAD operates normally, and by default the IAF remains on.
Unoccupied Mode
The unoccupied occupancy mode is the normal night time mode of UVC operation. During unoccupied mode the UVC uses the unoccupied heating and cooling set points, the OAD remains closed, and the IAF cycles as needed for heating or cooling. The IAF remains off when there is no need for heating or cooling.
Standby Mode
The standby mode is a special purpose daytime mode of UVC operation. During standby, mode the UVC uses the standby heating and cooling set points, the OAD remains closed, and by default the IAF remains on.
24 | McQuay OM 751 |
