Fan Speed − Reheat2 (FS.RH)
This configuration defines the fan speed used when Hot Gas Reheat (reheat2) is being requested. Fan speed is based on how many cooling stages the unit has, how many cooling stages are being requested, and how many reheat stages are being requested. If only reheat stages are being requested, then the fan speed will be set to FS.RH. If the unit only has one circuit of cooling, then the fan speed will be 100% when dehumidification and cooling is being requested. If the unit has more then one circuit of cooling and only one cooling stage is being requested, the fan speed will be set to FS.CL. Any time more then one cooling stage is requested the fan speed will be set to 100%. If only one cooling stage is requested and reheat is requested, then the fan speed will be set to the greater of the two configurations (FS.CL or FS.RH). (See Table 11.)
Fan Speed − Heating (FS.HT)
This configuration defines the intermediate fan speed used when in heating mode. Fan speed is based on how many heating stages the unit has and how many heating stages are actually on. If the unit only has one stage of heat, then the fan speed is set to 100% anytime the heat stage is on. If the unit has more than one stage of heat but only one heat stage is on, then the fan speed will be set to FS.HT. Any time more than one stage of heat is on, the fan speed is set to 100%.
Table 11 – Cooling Fan Speed Determination
Number | Cooling | Reheat |
| Fan | |
of | Stages | Stages | HVAC Mode | ||
Speed | |||||
Circuits | Requested | Requested |
| ||
|
| ||||
| 1 | 0 | Cooling | 100% | |
1 | 1 | >0 | Reheat1 | 100% | |
| 0 | >0 | Reheat2 | FS.RH | |
| 1 | 0 | Cooling | FS.CL | |
| >1 | 0 | Cooling | 100% | |
| >1 | >0 | Reheat1 | 100% | |
>1 |
|
| Reheat1/ | FS.CL | |
| 1 | >0 | or | ||
| Reheat2 | ||||
|
|
| FS.RH | ||
|
|
|
| ||
| 0 | >0 | Reheat2 | FS.RH |
Temperature Compensated Start
This logic is used when the unit is in the unoccupied state. The control will calculate early Start Bias time based on Space Temperature deviation from the occupied cooling and heating set points. This will allow the control to start the unit so that the space is at conditioned levels when the occupied period starts. This is required for ASHRAE 90.1 compliance. A space sensor is required for
Setting Up the System
The settings for temperature compensated start can be found in the local display under Configuration→UNIT.
ITEM | EXPANSION | RANGE UNITS CCN POINT | ||
TCS.C | Temp.Cmp.Strt.Cool Factr | 0 ‐ 60 | min | TCSTCOOL |
TCS.H | Temp.Cmp.Strt.Heat Factr | 0 ‐ 60 | min | TCSTHEAT |
Temp Comp Strt Cool Factr (TCS.C)
This is the factor for the start time bias equation for cooling.
Temp Comp Strt Heat Factr (TCS.H)
This is the factor for the start time bias equation for heating.
NOTE: Temperature compensated start is disabled when these factors are set to 0.
Temperature Compensated Start Logic
The following conditions must be met for the algorithm to run:
SUnit is in unoccupied state.
SNext occupied time is valid.
SCurrent time of day is valid.
SValid space temperature reading is available (sensor or CCN network).
The algorithm will calculate a Start Bias time in minutes using the following equations:
If (space temperature > occupied cooling set point)
Start Bias Time = (space temperature – occupied cooling set point)* TCS.C
If (space temperature < occupied heating set point)
Start Bias Time = (occupied heating set point – space temperature)*TCS.H
When the Start Bias Time is greater than zero the algorithm will subtract it from the next occupied time to calculate the new start time. When the new start time is reached, the Temperature Compensated Start mode is set, the fan is started and the unit controlled as in an occupied state. Once set, Temperature Compensated mode will stay on until the unit goes into the Occupied mode. The Start Bias Time will be written into the CCN Linkage Equipment Table if the unit is controlled in DAV mode. If the Unoccupied Economizer Free Cool mode is active when temperature compensated start begins, the Unoccupied Free Cool mode will be stopped.
NOTE: The maximum minutes Start Bias can be is 180.
Carrier Comfort Network (CCN)R Configuration
It is possible to configure the ComfortLink control to participate as an element of the Carrier Comfort Network (CCN) system directly from the local display. This section will deal with explaining the various programmable options which are found under the CCN
The major configurations for CCN programming are located in the local displays at Configuration→CCN. See Appendix A.
CCN Address (CCN.A)
This configuration is the CCN address the rooftop is assigned.
CCN Address (CCN.B)
This configuration is the CCN bus the rooftop is assigned.
CCN Baud Rate (BAUD)
This configuration is the CCN baud rate.
CCN Time/Date Broadcast (BROD"B.TIM)
If this configuration is set to ON, the control will periodically send the time and date out onto the CCN bus once a minute. If this device is on a CCN network then it will be important to make sure that only one device on the bus has this configuration set to ON. If more than one time broadcaster is present, problems with the time will occur.
NOTE: Only the time and date broadcaster can perform daylight savings time adjustments. Even if the rooftop is stand alone, the user may want to set this to ON to accomplish the daylight/savings function.
CCN OAT Broadcast (BROD"B.OAT)
If this configuration is set to ON, the control will periodically broadcast its
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