Occupancy Determination
The building’s occupancy is affected by a number of different factors. When the unit is operating with a space temperature sensor (T−55, T−56, T−58 or T−59), occupancy affects the unit set points and the operation of the economizer. If the unit is operating under thermostat control, occupancy only affects the operation of the economizer. If the unit’s Humidi−MiZer is being controlled by a relative humidity sensor, then occupancy will affect the RH setpoints. The factors affecting occupancy are listed below from highest to lowest priority.
Level 1 Priority
Level 1 classification is a force/write to occupancy and can occur three ways. Listed in order of priority: force on OCCUPIED, a write to NVI_OCC, and a Linkage write. The CCN point OCCUPIED is forced via an external device such as a ComfortIDt controller or a service tool. When OCCUPIED is forced to YES, the unit is considered occupied, when OCCUPIED is forced to NO, the unit is considered unoccupied. If the 3rd party protocol LON is writing to NVI_OCC, the control maps it to OCCUPIED as an input. If the unit is being controlled by Linkage, the occupancy is communicated and mapped to OCCUPIED as an input. LON and Linkage do not force the point, only write to it, therefore a force applied to OCCUPIED will override them.
If OCCUPIED is not being forced or written to, proceed to the level 2 priority.
Level 2 Priority
Remote Occupancy Switch should be configured to either Normally Open or Normally Closed when the user would like to control the occupancy with an external switch. This switch is field−supplied (24v, single pole, single throw [SPST]). There are three possible configurations for the remote occupancy switch:
1.(Configuration→UNIT→RM.SW = 0) No Switch
2.(Configuration→UNIT→RM.SW = 1) Normally Open Switch
3.(Configuration→UNIT→RM.SW = 2) Normally Closed Switch
If the switch is configured to No Switch (0), the switch input value will be ignored and software will proceed to level 3 priority. For each type of switch, the appropriate configuration and states are
listed in the table below. The Remote Occupancy Switch (INPUTS→GEN.I→RM.OC) point will show the status of the switch.
| SWITCH | STATE OF SWITCH | |
TYPE OF SWITCH | AND STATE OF | ||
CONFIGURATION | |||
| OCCUPANCY | ||
|
| ||
Occupied when Closed |
| Open and Unoccupied | |
or Unoccupied when | Normal Open (1) | Closed and Occupied | |
Open |
| ||
Occupied when Open or |
| Open and Occupied | |
Unoccupied when | Normal Closed (2) | Closed and Unoccupied | |
Closed |
|
NOTE: To perform remote occupancy, an Economizer Control Board must be installed in the unit.
Level 3 Priority
The following occupancy options are determined by the state of Occupancy Schedule Number (Configuration→CCN→SCH.O →SCH.N) and the Global Schedule Broadcast (Configuration →CCN→ BROD→B.GS).
1.(Configuration→CCN→SCH.O→SCH.N = 0)
The unit is always considered occupied and the programmed schedule is ignored. This is the factory default.
2.(Configuration→CCN→SCH.O→SCH.N = 1−64) Follow the local programmed schedule. Schedules 1 to 64 are local within the controller. The unit can only store one
local schedule and therefore changing this number only changes the title of the schedule table.
3. (Configuration→CCN→SCH.O→SCH.N = 65−99) Follow the global programmed schedule. If the unit is configured as a Global Schedule Broadcaster (Configuration→CCN→BROD→B.GS = YES), the unit will follow the unit’s programmed schedule and broadcast the schedule so that other devices programmed to follow this schedule number can receive the schedule. If the unit is not programmed as a Global Schedule Broadcaster (Configuration→CCN→BROD→B.GS = NO), the unit will receive broadcasted schedules from a unit programmed to broadcast this schedule number. While using the programmed schedule, occupancy can be temporarily switched from unoccupied to occupied by pressing the override button for approximately 3 seconds on the T−55, T−56, T−58 or T−59 space temperature sensor. Override will only occur if SPT Override Enabled (Configuration →CCN→SCH.O→OV.SP) is set to YES. The length of the override period when pressing the override button is determined by the Override Time Limit (Configuration →CCN→SCH.O→OV.TL). The hours remaining in override is displayed as Timed Override Hours (Configuration→CCN→SCH.O→OV.EX). This point can also be changed from the local display or network to set or change the override period length.
Indoor Fan Operation
The indoor fan is controlled by the Indoor Fan Relay (Outputs →FANS→IDF) on the MBB (main base board) control, which then operates the indoor fan contactor (IFC). For gas heating units, the IGC control fan output is also monitored by the MBB control. This can result in additional modification of fan delays or other operation due to safety functions of the IGC control. The Humidi−MiZert gas heating units do not monitor the IGC fan output; instead an indoor fan on relay (IFOR) is used to allow the IGC to turn the fan on. If configured for IAQ fan operation, the fan may be turned on to satisfy air quality demands. See the Indoor Air Quality section if using IAQ (indoor air quality) accessory sensors. The fan can only be turned on under thermostat or space sensor control if the System Mode (SYS) status is enabled. The fan will remain on if compressors or heat relays are ever stuck on. If configured for fan status switch (FN.SW) and Shut Down on IDF Failure (Configuration→UNIT→IDF.F = Yes) is enabled, the fan and unit will be shutdown on alarm. See the Adaptive Fan section for information on its operation.
Thermostat Control
In thermostat mode, the IDF relay will be on in the following situations: fan request G in ON, cooling request Y1 or Y2 is ON, or heating request W1 or W2 is ON. If G is dropped or never on with an Y1, Y2, W1, or W2 call, the IDF relay will turn off after a configurable time delay with respect to the HVAC mode that is ending. The Fan−off Delay delays are as follows: Mech Cool (Configuration→COOL→FOD.C), Elect Heat (Configuration →HEAT→FOD.E), and Gas Heat (Configuration→HEAT →FOD.G).
Space Sensor Control
In Space Sensor mode, the IDF relay will be on if the unit is in Occupied mode and the indoor fan is configured to always run while occupied (Configuration→UNIT→OC.FN = YES). If the indoor fan is configured for intermittent fan (Configuration →UNIT→OC.FN = No), the fan will only be on when there are cooling, heating, or dehumidification stages running; or if there is an air quality demand. During the unoccupied period, the fan will operate intermittent. With intermittent fan, the IDF relay will turn off after a configurable time delay with respect to the HVAC mode that is ending. The Fan−off Delay delays are as follows: Mech Cool (Configuration→COOL →FOD.C), Elect Heat
(Configuration→HEAT→FOD.E), and Gas Heat (Configuration→HEAT→FOD.G).
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