The following table describes the attributes used by this module.
|
Name |
Description |
Default Value |
|---|---|---|
|
Cooling Required |
Indicates cooling demand. When this input is True, the Start/Stop module initiates a start up sequence. |
False |
|
Damper Close Delay |
Time required to close the dampers before turning the fan off. |
90 Seconds |
|
Duct Static Pressure |
Contains the value of the duct static pressure used by this module and passed to the Supply Fan Output controller. |
Display Units: Pa, in. W.C. |
|
Duct Static Pressure 1 |
Supply air duct static pressure. The unit may have two pressure sensors. When the application has one pressure sensor, it must be connected to both Duct Static Pressure 1 and Duct Static Pressure 2. |
0 Pa, 0.00 in. W.C. |
|
Duct Static Pressure 2 |
Supply air duct static pressure. The unit may have two pressure sensors. When the application has one pressure sensor, it must be connected to both Duct Static Pressure 1 and Duct Static Pressure 2. |
0 Pa, 0.00 in. W.C. |
|
Duct Static Pressure Setpoint |
Contains the supply air static pressure setpoint. This input is used to trigger a state change if the supply fan type is variable speed and static pressure control is used. |
250 Pa, 1.00 in. W.C. |
|
Fan Ready |
Indicates that the Start/Stop sequencer has reached the On State. The temperature control sequencers (such as the MA SD Sequencer or the MA CD Sequencer) use this information to allow DAT temperature sequencing. This output is delayed one operational cycle after the State output to ensure the Fan Ready output is in sync with the control status inputs (Damper CS, Cooling CS, Preheat CS, and so on) on the lower level sequencers. |
|
|
Fan Sequence |
Indicates which fan must start first. The module supports three cases, supply fan first (SF First), return fan first (RF/EF First), and supply fan only (SF Only) for the case where there is no return fan. |
SF First Set Name: AHU Fan Sequence |
|
Fan Start Delay |
Time delay between starting the first fan and starting the second fan. |
10 Seconds |
|
Fan Stop Delay |
Serves a dual purpose. It is the time delay between stopping the first and second fan, and it is the time delay between stopping the second fan and allowing the system to restart. |
30 Seconds |
|
Heating Required |
Indicates heating demand. When this input is True, the Start/Stop module initiates a start up sequence depending on the status of the Preheat Bonnet Switch, Preheat Percent Cmd, Reheat Bonnet Switch, and Reheat Percent Cmd. |
False |
|
Minimum OA Position |
Defines the minimum position for the OAD and the EAD. It is used to calculate the Ramp OA delay time used by the FSM. |
0% |
|
Occupancy |
Contains the occupancy status for the unit. |
Occupied Set Name: Occ Effective |
|
Preheat Bonnet Switch |
Contains the bonnet switch input from the preheat device. It indicates whether preheat is hot enough for the fan to start. The bonnet switch is used to provide a supply fan on delay when the AHU has gas heat. The bonnet switch is only supported in systems with a single speed supply fan which starts first. |
Hot Set Name: Cold/Hot |
|
Preheat Percent Cmd |
Contains the heating command to the preheat device. This input is used to determine if the unit is heating and if heating or cooling are required. |
1.0% |
|
Proof of Airflow |
Shows the current airflow status. The output may be either True, False, or Fault. True means the fan was commanded on and airflow has been detected. False means the fan was not commanded on. Fault means the fan is commanded on, but airflow proof has not been detected. This input is used to restart the supply fan after a fan status fault. |
False Set Name: False/True/Fault |
|
Ramp Rate |
Defines the rate of change in damper position. It is used to calculate the Ramp OA delay time used by the FSM. |
50 Change per Minute |
|
Reheat Bonnet Switch |
Bonnet switch input from the reheat device. It indicates reheat is hot enough for the fan to start. The bonnet switch is used to provide a supply fan on delay when the AHU has gas heat. The bonnet switch is only supported in systems with a single speed supply fan which starts first. |
Hot Set Name: Cold/Hot |
|
Reheat Percent Cmd |
Contains the heating command to the reheat device. This input is used to determine if the unit is heating and if heating or cooling are required. |
1.0% |
|
Stabilize Delay |
Defines the amount of time it takes to circulate air within the AHU to stabilize temperatures before opening the dampers. |
60 Seconds |
|
STARTSTOP-STATE (State) |
Current state of the finite state machine. This output is connected to the state selection matrix. |
Set Name: AHU MA StartStop States |
|
Supply Fan OnOff |
Indicates if the supply fan is responding to this sequencer. This input is the control signal for the supply fan. The enumeration set only has two values, Off and On. |
Off Set Name: Off/On |
|
Supply Fan Percent Cmd |
Contains the current value of the supply fan output. |
0% |
|
Supply fan Type |
Indicates the air handler supply fan type. The module supports two supply fan types, variable capacity and constant capacity. |
Variable Capacity Set Name: AHU Supply Fan Type |