28
HVAC Mode Numerical Form (H.NUM)
This is a numerical representation of the HVAC modes which
may be read via a point read.
SYSTEM MODES (OPERATING MODES
SYS.M)
System Mode Off
When the system mode is OFF, all outputs are to be shut down
and no machine control is possible. The following list displays
the text assigned to the System Mode when in the OFF mode
and the conditions that may cause this mode are checked in the
following hierarchal order:
1. Wake up timer on a power reset.
(“Initializing System ...”)
2. System in the process of shutting down compressors and
waiting for timeguards to expire.
(“Shutting Down ...”)
3. Factory shut down (internal factory control level — SHUT-
DOWN).
(“Factory Shut Down”)
4. Unit stop (software application level variable that acts as a
hard shut down — Service Test
STOP).
(“Local Machine Stop”)
5. Fire shut down (traumatic fire shutdown condition based on
the Fire Shutdown Input — Inputs
FIRE
FSD).
(“Fire-Shutdown Mode”)
6. Emergency stop, which is forced over the CCN through the
Emergency Stop Variable (EMSTOP).
(“CCN Emergency Stop”)
7. Startup delay.
(“Startup delay = 0 to 900 secs”)
8. Service test ending transition timer.
(“Service Test Ending”)
9. Unexplained internal software failure.
(“Internal Failure”)
System Mode Test
When the system mode is Test, the control is limited to the Test
mode and is controllable via the local displays (scrolling mar-
quee and Navigator™ display) or through the factory service
test control. The System Test modes are Factory Test Enabled
and Service Test Enabled. See the Service Test Mode section
for details on test control in this mode.
1. Factory Test mode
(“Factory test enabled”)
2. Service Test mode
(“Service test enabled”)
System Mode Run
When the system mode is Run, the software application in the
control is free to run the HVAC control routines by which cool-
ing, heating, IAQ, etc., is possible. There are two possible text
displays for this mode, one is normal run mode and the other
occurs if one of the following fire-smoke modes is present:
smoke purge, pressurization or evacuation.
1. Normal run time state
(“Unit Operation Enabled”)
2. Fire-Smoke control mode
(“Fire-Smoke Control”)
HVAC MODES (OPERATING MODE
HVAC)
The system mode must be selected before the unit controls can
select the HVAC mode of the rooftop unit. The selection of an
HVAC mode is based on a hierarchal decision making process.
Certain overrides may interfere with this process and the nor-
mal temperature/humidity control operation of the unit. The
decision making process that determines the HVAC mode is
shown in Fig. 3 and Appendix D.
Each HVAC Mode is described below. The HVAC mode num-
ber is shown in parenthesis after the mode.
HVAC Mode — STARTING UP (0)
The unit is transitioning from the OFF mode to a different
mode.
HVAC Mode — DISABLED (1)
The unit is shut down due to a software command disable
through the scrolling marquee, a CCN emergency stop com-
mand, a service test end, or a control-type change delay.
HVAC Mode — SHUTTING DOWN (2)
The unit is transitioning from a mode to the OFF mode.
HVAC Mode — SOFTSTOP REQUEST (3)
The unit is off due to a soft stop request from the control.
HVAC Mode — REM SW.DISABLE (4)
The unit is off due to the remote switch.
HVAC Mode — FAN STATUS FAIL (5)
The unit is off due to failure of the fan status switch.
HVAC Mode — STATIC PRESSURE FAIL (6)
The unit is off due to failure of the static pressure sensor.
HVAC Mode — COMP.STUCK ON (7)
The unit is shut down because there is an indication that a com-
pressor is running even though it has been commanded off.
HVAC Mode — OFF (8)
The unit is off and no operating modes are active.
HVAC Mode — TEST (9)
The unit is in the self test mode which is entered through the
Service Test menu.
HVAC Mode — TEMPERING VENT (10)
The economizer is at minimum vent position but the supply-air
temperature has dropped below the tempering vent setpoint.
Staged gas heat is used to temper the ventilation air.
HVAC Mode — TEMPERING LOCOOL (11)
The economizer is at minimum vent position but the combina-
tion of the outside-air temperature and the economizer position
has dropped the supply-air temperature below the tempering
cool setpoint. Staged gas heat is used to temper the ventilation
air.
HVAC Mode — TEMPERING HICOOL (12)
The economizer is at minimum vent position but the combina-
tion of the outside-air temperature and the economizer position
has dropped the supply-air temperature below the tempering
cool setpoint. Staged gas heat is used to temper the ventilation
air.
HVAC Mode — VENT (13)
This is a normal operation mode where no heating or cooling is
required and outside air is being delivered to the space to con-
trol IAQ levels.
HVAC Mode — LOW COOL (14)
This is a normal cooling mode where a low cooling demand is
required.
HVAC Mode — HIGH COOL (15)
This is a normal cooling mode where a high cooling demand is
required.
To Next Page
Loading...
