Unit installation

Controls
SCXF-SVX01K-EN 65
a. diagnostic and mode status signals to the remote
panel (LEDs) and to the Human Interface.
b. control of the binary alarm output on the RTM.
c. control of the binary outputs on the GBAS module
to inform the customer of the operational status
and/or diagnostic conditions.
Occupied/Unoccupied Inputs
There are four ways to switch to occupied/unoccupied:
1. Field-supplied contact closure hard wired binary input
to the RTM
2. Programmable night setback zone sensor
3. Tracer Summit
4. Factory-mounted time clock
VAV Changeover Contacts
These contacts are connected to the RTM when daytime
heating on VAV units with internal or external hydronic
heat is required. Daytime (occupied) heating switches the
system to a CV unit operation. Refer to the unit wiring
diagram for the field connection terminals in the unit
control panel.The switch must be rated at 12 ma @ 24VDC
minimum.
External Auto/Stop Switch
A field-supplied switch may be used to shut down unit
operation.This switch is a binary input wired to the RTM.
When opened, the unit shuts down immediately and can
be cancelled by closing the switch. Refer to the unit wiring
diagrams (attached to the unit control panel) for proper
connection terminals.The switch must be rated for 12 ma
@ 24 VDC minimum. This input will override all VOM
inputs, if the VOM option is on the unit.
Occupied/Unoccupied Contacts
To provide night setback control if a remote panel with
night setback was not ordered, install a field-supplied
contact.This binary input provides the building’s
occupied/unoccupied status to the RTM. It can be initiated
by a time clock, or a building automation system control
output.The relay’s contacts must be rated for 12 ma @ 24
VDC minimum. Refer to the appropriate wiring diagrams
(attached to the unit control panel for the proper
connection terminals in the unit control panel.
Emergency Stop Input
A binary input is provided on the RTM board for
installation of a field-supplied normally closed (N.C.)
switch to use during emergency situations to shut down all
unit operations. When open, an immediate shutdown
occurs. An emergency stop diagnostic enters the human
interface and the unit will require a manual reset. Refer to
the unit wiring diagrams (attached to the unit control panel
for the proper connection terminals.The switch must be
rated for 12 ma @ 24 VDC minimum.This input will
override all VOM inputs, if the VOM option is on the unit.
VAV Box Option
To interlock VAV box operation with evaporator fan and
heat/cool modes, wire theVAV boxes/air valves toVAV box
control connections on the terminal block.
Supply Duct Static Pressure Control
The RTM relies on input from the duct pressure transducer
when a unit is equipped with VFD to set the supply fan
speed to maintain the supply duct static pressure to within
the static pressure setpoint deadband.
RTM Sensors
RTM sensors include: zone sensors with or without
setpoint inputs and modes, supply air sensor, duct static
pressure, outside air temperature, outside air humidity,
airflow proving, and dirty filter.
Table 40. RTM sensor resistance vs. temperature
Temperature
°F
Resistance
V ohms
Temperature
°F
Resistance
V ohms
-40 346.1 71 11.60
-30 241.7 72 11.31
-20 170.1 73 11.03
-10 121.4 74 10.76
-5 103.0 75 10.50
0 87.56 76 10.25
5 74.65 77 10.00
10 63.8 78 9.76
15 54.66 79 6.53
20 46.94 80 9.30
25 40.40 85 8.25
30 34.85 90 7.33
35 30.18 100 5.82
40 26.22 105 5.21
45 22.85 110 4.66
50 19.96 120 3.76
55 17.47 130 3.05
60 15.33 140 2.50
65 13.49 150 2.05
66 13.15 160 1.69
67 12.82 170 1.40
68 12.50 180 1.17
69 12.19 190 0.985
70 11.89 200 0.830
Table 41. RTM setpoint analog inputs
Cooling or Heating
Setpoint Input, °F
(using RTM as zone
temp. source) ohms
Cooling Setpoint Input, °F
(using RTM as supply air temp.
source) resistance,
V
40 40 1084
45 45 992