will not be interrupted to the burners and heating will continue. Once modified, the fan on delay will not change back to 45 seconds unless power is reset to the control. When the indoor fan turns on after the 40 or 45 second delay the indoor fan will run at 100% fan speed.
Gas Heat Staging
When additional heat is required, power is supplied to the second stage of the main gas valve. When the space temperature is 0.5F above the Occupied Heat Set Point (Setpoint→OHSP) or Unoccupied Heat Set Point (Setpoint→UHSP) power is removed from the second stage of the main gas valve and to the IGC W1 terminal. Both stage 1 and stage 2 of the gas valve closes, interrupting the flow of gas to the main burners.
Gas Heat Shut Down
If power to the IGC W1 terminal lasted less than 1 minute, the heating cycle will not terminate until 1 minute after power is applied to the W1 terminal of the IGC board. If the over temperature limit opens after the indoor motor is stopped within 10 minutes of W1 becoming inactive, on the next cycle the time will be extended by 15 seconds. The maximum delay is 3 minutes. Once modified, the fan off delay will not change back to 45 seconds unless power is reset to the control. A LED indicator is provided on the IGC to monitor operation. The IGC is located in the gas burner section and can be accessed by opening the gas access door. During normal operation, the LED is continuously on.
Gas Heat with Economizer
When there is a call for heat as described above the indoor fan will operate at the Supply Fan Maximum Speed (Configuration→UNIT→FS.MX) configuration setting and the economizer outdoor air damper will move to the Econ Min at Max Fan Speed (Configuration→ECON→MP.MX) position. The economizer outdoor air damper is closed when the indoor fan is not operating.
Electric Heating Mode Using Space Temperature Sensor T55, T56, or T58 (50PD Units Only)
For electric heat units with factory installed electric heat, the Type of Heat Installed (Configuration→HEAT→HT.TY) will be factory set to a value of 2 and the Number of Heat Stages (Configuration→HEAT→N.HTR) will be factory set to match the installed heater. If electric heat is installed in the field the value for Number of Heat Stages (Configuration→HEAT→N.HTR) must be changed to match the number of heat stages installed.
Heat will not operate if the outdoor temperature is greater that the value configured for the Heating Lockout Temperature (Configuration→HEAT→HT.LO), Heat Minimum On Time (Configuration→HEAT→MRT.H) and Heat Minimum Off Time (Configuration→HEAT→MOT.H). Timeguards apply to both stages of heating. Factory defaults values are 2 minute s ON and 2 minutes OFF.
If the indoor fan control is configured to cycle with the heating demand by setting Fan ON When Occupied Heat Minimum On Time (Configuration→UNIT→OC.FN) to NO, the fan will stop after a delay configured by Fan-off Delay, Elect Heat (Configuration→HEAT→FOD.E). The factory default for Fan-off Delay, Elect Heat (Configuration→HEAT→FOD.E) is 30 seconds.
The electronic control uses information from the space sensor to determine the number of heat stages required. Once the number of stages needed for heating is determined, either Heat Stage 1 Relay (Outputs→HEAT→HT.1), or Heat Stage 1 Relay
(Outputs→HEAT→HT.1) and Heat Stage 2 Relay
(Outputs→HEAT→HT.2) outputs will be turned on. See Gas Heating Mode Using Space Temperature Sensor for more information.
Supply-Air Temperature Sensor (SAT)
The SAT Heat Mode Sensing (Configuration→HEAT→SAT→SAT.H) affects the Supply Air Temperature (Temperatures→AIR.T→SAT) value displayed. This configuration is accessible via the Scrolling Marquee on the SAT Heat Mode Sensing (Configuration→HEAT→SAT→SAT.H).
When the SAT Heat Mode Sensing (Configuration→HEAT→SAT→SAT.H) =DSBL, the Supply Air Temperature (Temperatures→AIR.T→SAT) value on the Scrolling Marquee and the CCN tables will be forced to zero when heat outputs come ON and for 5 minutes after. The default Supply Air Temperature (Temperatures→AIR.T→SAT) location is at the fan inlet, upstream of the heat section.
When the SAT Heat Mode Sensing (Configuration→HEAT→SAT→SAT.H) = ENBL, the Supply Air Temperature (Temperatures→AIR.T→SAT) sensor reading is displayed at the Scrolling Marquee and the CCN tables during heating mode. This setting should only be used if the original SAT sensor wires are removed from the Main Base Board (MBB) and replaced by an accessory SAT sensor located in the supply duct downstream of the heat section. There are then two supply air temperature limits that become active, the Maximum SAT Lower Level (Configuration→HEAT→SAT→SAM.L) the Maximum SAT Upper Level (Configuration→HEAT→SAT→SAM.U). Any time the supply air temperature rises above the Maximum SAT Lower Level (Configuration→HEAT→SAT→SAM.L) the heat staging will be limited to what is currently on and no additional stages can be added until the supply air temperature falls
below the Maximum SAT Lower Level (Configuration→HEAT→SAT→SAM.L). If the supply air temperature rises above the Maximum SAT Upper Level (Configuration→HEAT→SAT→SAM.U), then heating will be reduced by removing a heat stage. That stage can not be added
again until the Supply Air Temperature (Temperatures→AIR.T→SAT) falls below the Maximum SAT Lower Level (Configuration→HEAT→SAT→SAM.L). If the supply air temperature stays above the Maximum SAT Upper Level (Configuration→HEAT→SAT→SAM.U), then another stage will be removed after the Heat Stage Decrease Time (Configuration→HEAT→H.DEC).
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.
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.
IMPORTANT: Temperature compensated start is disabled when these factors are set to 0.
