| System Control Options (contd.)
OCCUPIED
COOLING MODE — The occupied cooling mode state
begins when the conditioned zone temperature rises 2 degrees F plus maximum control overshoot above the morning
warm-up setpoint setting. The unit control module
conditions are as follows:
- The heat/cool mode output is de-energized.
- The economizer and mechanical cooling functions are permitted to operate in
response to limit controls and supply air temperature.
- The cooling tower/condenser water pump interlock output cycles on and off based
on the need for cooling.
- The supply air fan is on continuously.
- The airside economizer fresh air damper (if provided) is open to its minimum
position or greater.
NIGHT HEAT/MORNING WARM-UP OVERRIDE — This feature consists of a
switch which is mounted on the side of the night heat
zone sensor. To initiate the override, the switch
button must be pushed for 1 second. The unit will then return to the occupied mode
for two hours. This time period is remotely adjustable
from the Tracer® with the Integrated Comfort™
system interface control option.
Night Heat Morning Warmup Control
This control option is identical to the Programmable Night Heat Morning Warmup
Control described above except that the programmable
timer is not provided. Therefore, an unoccupied input (a set of terminals) is provided to switch the unit into the
unoccupied mode. The unit control is accomplished as
follows:
- The Night Heat Mode is activated by a switch or contact closure to the unoccupied input.
- The Morning Warm-up Mode is initiated by a switch or contact opening to
the unoccupied input.
- When the morning warm-up temperature
setpoint is reached, the unit will switch over to the
Occupied Heating Mode.
- The Occupied Cooling Mode state begins when the conditioned zone temperature
rises 2 degrees F above the morning warm-up setpoint
setting. The system must progress through the unoccupied mode to return to the
occupied heating mode.
Integrated Comfort™ System Interface
This option allows interface between the Tracer® Building Automation System and
the self-contained unit through a two wire serial data
link. The Tracer system provides external signals to the unit control module in a supervisory role to coordinate the operation
of the self-contained unit with the rest of the
building HVAC system.
SYSTEM OPERATION – In order for the Tracer system to act in a supervisory
role the unit switch must be in the Auto Remote
position. If the unit switch is in either the Auto
Local or Stop/Reset positions, the Tracer system can interrogate the unit and
gather information but cannot control the unit. Tracer
system inputs to the unit will be stored but not used.
This option includes a non-volatile memory to hold in storage certain setpoints,
data, and diagnostic codes in the event of a power
outage or failure of the serial data link.
COMMUNICATIONS LINK – The communication link between a Tracer and the
self-contained units is by a single twisted pair of
wires. The self-contained units can be "daisychained" together with this single shielded twisted pair of wires resulting in substantially less installation
cost than conventional "hardwired" energy
management systems. The Tracer 100 system will accommodate a maximum of 12 self-contained
units and up to eight Tracer 100 units can be linked to
form a system capable of handling up to 96 self-contained units. A single Tracer
1000 system can accommodate up to 80 self-contained units.
OPERATING MODES – The following modes can be initiated or changed by
the Tracer system:
Auto/Stop — Auto puts the self-contained unit into operation responding to internal (unit control module)
and external (Tracer) control inputs. Stop shuts the
unit down. In addition, a hardwired input to the
External Interlock Auto/Stop may also be used.
Occupied/Unoccupied — The Tracer system directs the unit control module
to operate in the Programmable Night Heat Morning
Warmup mode. The unit will operate in the manner described above in the Programmable
Night Heat Morning Warmup Control section with the
Tracer system acting as the time clock. The Night Heat/Morning Warmup Override
function is available but the unit control module
will not respond to the override signal unless authorized by the Tracer system.
Fan On Ventilate — In this mode the fan is started, the ventilate output energized and the airside economizer fresh air
damper (if present) driven full open. The cooling and
heating functions are locked out. A hardwired Fan On Ventilate input may also be used.
SETPOINTS — With the Integrated Comfort Systems InterFace option, the
following setpoints can be set from the Tracer system:
a. Supply air temperature on VAV units
b. Day cooling on non-VAV units
c. Supply air pressure on VAV units
with inlet guide vanes
d. Morning warmup or day heat
c. Airside economizer minimum position
d. Night heat
e. Default supply air temperature on
VAV units
f. Default day cooling on non-VAV units
g. Default supply air pressure on VAV
unit with inlet guide vanes
All of the above items are stored in non-volatile memory.
STATUS MONITORING – The Integrated Comfort systems interface option
provides an extensive monitoring capability which
allows building operators and maintenance personnel easy access to a host of unit status and operating information at the
Tracer computer. All of the diagnostic and operating
state displays that are available at the unit |
