Remote Controls Group; Space Temperature Offset (Cv Only); Special Systems Group - Carrier 48FP Controls Operation And Troubleshooting

Remote Controls Group —
mote Start (Occupied/Unoccupied status control) and Space
Temperature Offset (CV only).
REMOTE START — The Remote Start function allows a
general-purpose building/energy management system to signal
the unit to switch between Unoccupied and Occupied modes
from a remote location. This function will also override a
Standby command status by initiating an Occupied mode.
Upon removal of remote signal, unit will switch to Unoccupied
mode. An external control signal (24-vac) is required.
NOTE: Unit cannot be returned to Standby mode from
a remote signal. Standby can only be re-entered via HSIO
command.
Application of the 24-v signal will switch the unit from cur-
rent mode (Standby or Unoccupied) to Occupied. The unit will
initiate Occupied modes as determined by set points. Removal
of the 24-v signal will return control to Unoccupied mode.
Install a LOCAL/REMOTE (SPST-OFF/ON) manual
switch in the 24-v signal input. A setting of LOCAL (OFF)
prevents accidental start caused by remote control system dur-
ing service or maintenance. A setting of REMOTE (ON) al-
lows the remote system to start unit with a 24-v signal.
Configuration — Connect remote signal leads to Channel 49
(DSIO no. 2, J3-1, J3-2). To ensure unit returns to Unoccupied
mode whenever signal is removed, provide Time Schedule for
Unoccupied periods as 24 hr per day (zero hours for Occupied
period).
SPACE TEMPERATURE OFFSET (CV Only) — The
Space Temperature Offset (STO) function permits occupants to
adjust the space temperature set point by ±5 F, using a T-56
sensor (equipped with sliding scale adjustment).
A T-56 Space Sensor (field-supplied and -installed) is
required.
Sequence of Operation — The STO channel provides analog
input to the control, indicating desired shift in space set point.
The control scales the voltage to –5 to +5 F range. The config-
ured Space Temperature Set Point is altered by the offset value.
Configuration — To configure, connect the T-56 lead from
"SW" terminal to PSIO1 Terminal 33 (via TB3-3).
Special Systems Group —
dronic Heating Control, Freezestat, Lead/Lag, Head Pressure
Control (Motormaster® Control), and Transducers and Ther-
mistors feature.
HYDRONIC HEATING — The Hydronic Heating function
will modulate a control valve in a steam or hydronic heat sys-
tem (field-supplied and -installed), to maintain building tem-
perature at user configured set point. Analog output is 4 to
20 mA. See Table 38.
Table 38 — Hydronic Heating Definitions
ITEM
HCFO Heating Coil Fan Off Value
HCSCV Heating Coil Submaster Center Value
HCSMG Heating Coil Submaster Gain
HCSR Heating Coil Submaster Reference
HCV Heating Coil Value (Analog)
IAQ Indoor Air Quality Function
OHEN Occupied Heating Enable/Disable
OHSP Occupied Heating Set Point
RAT Return-Air Temperature
SAT Supply-Air Temperature
SPT Space Temperature
UHSP Unoccupied Heating Set Point
A heating coil with proportional control valve (field-
supplied and -installed) is required. A field-supplied
This group includes Re-
This group includes Hy-
DEFINITION
connection from the control valve to Channel 43 is also re-
quired. The control options module (available as a factory-in-
stalled option or field-installed accessory on size 034-074 units
and is standard on 078-104 units) is required for hydronic heat-
ing.
Sequence of Operation
1. If the supply fan is OFF, or if Unoccupied Free Cool-
ing is active, the heating value is modulated to main-
tain desired minimum supply-air temperature (HCFO).
2. If the supply fan is on, unit is in Occupied mode, or
Optimal Start or Unoccupied heat modes are active:
VAV Units — The Control will determine if heating is
required. Heating is required if the return-air tempera-
ture (RAT) is less than the heating set point and the
unit is one of the following: in Unoccupied mode, per-
forming warm-up, or Occupied Heating is enabled.
When heating is required, control will modulate heat-
ing coil control valve to maintain desired supply-air
temperature.
CV Units — The control reads the space temperature
sensor value and calculates the required heating coil
control value (the supply-air temperature required to
satisfy load conditions). The control will modulate
heating coil control valve to maintain desired SAT
control value.
3. When heating is activated, the HIR relay will be
energized.
4. A possible override of the Hydronic Heating function
may occur if the IAQ Reheat function is active.
Configuration — See Table 39. To configure:
1. Select Heat Type. Press
tion. Scroll down to HEAT. Set Type to 1 (water/
steam). Enable Data Reset.
2. Enable Occupied Heating (optional). Press
enter the subfunction. Scroll down to OHEN. Press
to enable Occupied heating.
ENTER
3. Select Heating set points. Press
subfunction.
a. Set the Occupied Heating Set Point. Scroll down to
OHSP. The default is 68 F. The range is 55 to 80 F.
b. Set the Unoccupied Heating Set Point. Scroll down
to UHSP. The default is 55 F. The range is 40 to
80 F.
4. Select Heat Coil Fan Off set point. Use the
ComfortWORKS® software to select the Heat Coil
Fan Off set point. The default is 40 F. The range is 35
to 65 F.
Algorithms
HCSR = PID function on (Demand term)
where:
VAV: (Demand term)
= Heating set point – Return Air Temperature
CV: (Demand term)
= Heating set point – Space Temperature
FREEZESTAT — The Freezestat function will attempt to pre-
vent freezing at the Hydronic Coil by raising temperature in the
coil (by opening control valve on low temperature signal). The
function also turns the supply fan off and returns economizer
dampers to minimum position.
A contact set (Normally Open, 24-vac pilot duty) is re-
quired. Contact set will close on fall in temperature at freezestat
set point. The control options module (available as a factory-in-
stalled option or field-installed accessory on size 034-074 units
and is standard on 078-104 units) is required for operation.
31
to enter the subfunc-
to
to enter the