Carrier 38APS025 - C.TYP=1 (VAV) Required Configuration; Space Temperature Control Mode Response for C.TYP=1 (VAV)

66
Table 25 — C.TYP=1 (VAV) Required Configuration
LEGEND
Sequence of Operation — The MBB uses Cooling Setpoint 1
(Setpoints
o
COOL
o
CSP.1) as the basis for the Active Set
Point (Run Status
o
VIEW
o
SETP). The Control Point (Run
Status
o
VIEW
o
CTPT) is the Active Set Point (SETP) or
Cooling Set Point 1 (CSP.1) adjusted for any temperature reset
that is applied. See Temperature Reset on page 129 for addi-
tional information.
For mechanical cooling, the unit’s Control Method
(Configuration
o
OPT2
o
CTRL) and inputs must allow the
machine to run. See Control Methods on page 60 for addition-
al information.
On power up or changing from Off to Enabled, the machine
will remain off until Minutes Off Time (Configuration
o
OPT2
o
DELY) timer has expired. See Minutes Off Time on
page 128 for additional information. Liquid Line Solenoid
Valve operation is as described in Liquid Line Solenoid Valves
on page 40. Time Guard is honored for all compressors. For
specific information on Time Guard, see MDTG - Time Guard
Active on page 135.
In this Control Type, Space Temp Control Mode, Run Sta-
tus
o
VIEW
o
SPT.M=0 (Off Cool) as long as Run Sta-
tus
o
VIEW
o
STAT=1 (Off Local), 2 (Off CCN), 3 (Off Time)
or 4 (Off Emrgcy). SPT.M=3 (Cool On) exists when Control
Mode, STAT=5 (On Local), 6 (On CCN), or 7 (On Time). In
this Control Type, if the Indoor Fan Status Switch opens, In-
puts
o
GEN.I
o
ID.F.A=OFF, Control Mode (STAT) will
change to 8 (IDFS Not On); the unit will alarm and switch to 4
(Off Emrgcy). Table 26 shows the space temperature control
mode response for C.TYP=1.
Table 26 — Space Temperature Control Mode
Response for C.TYP=1 (VAV)
38APD Units — On a call for cooling, the Indoor Fan Status
Cir A (Inputs
o
GEN.I
o
ID.F.A) is checked. The switch must
be closed before the capacity routine will start. The lead circuit
is determined (see Lead/Lag Determination on page 112). The
lead compressor will be determined and started (see Circuit
Compressor Staging on page 112). If the lead compressor is a
digital compressor and is enabled, the compressor will start
fully loaded for 90 seconds prior to starting to cycle between
loaded and unloaded. Compressors will be staged until the
unit’s supply air temperature meets the Control Point (CTPT)
as described in Supply Air Temperature Control on page 110.
If additional capacity requires the lag circuit to start, the lag
circuit’s lead compressor will be determined and started. Dur-
ing operation, the controls will stage the condenser fans to
maintain head pressure. See Head Pressure Control on
page 117.
As part of normal operation, if a single compressor in a mul-
tiple compressor circuit (38APD040-130) operates for the cu-
mulative time of 60 minutes without an increase in circuit ca-
pacity, an oil recovery routine is initiated. When this routine is
initiated, a second compressor in the circuit is started. Once
started, the normal capacity control routine takes priority and
will turn off the compressor if needed.
As the capacity requirement begins to decrease, the ma-
chine controls will reduce the unit’s capacity to maintain the
Control Point. If the unit is equipped with Minimum Load
Control, it will not be active until the unit is on its last stage of
capacity.
38APS Units — On a call for cooling, the Indoor Fan Status
Cir A (Inputs
o
GEN.I
o
ID.F.A) is checked. The switch must
be closed before the capacity routine will start. The lead com-
pressor will be determined and started. See Circuit Compressor
Staging on page 112. If the lead compressor is a digital com-
pressor and is enabled, the compressor will start fully loaded
for 90 seconds prior to starting to cycle between loaded and
unloaded. Compressors will be staged until the unit’s capacity
meets the Control Point (CTPT) as described in Supply Air
Temperature Control on page 110. During operation, the con-
trols will stage the condenser fans to maintain head pressure.
See Head Pressure Control on page 117.
As part of normal operation, if a single compressor operates
for the cumulative time of 60 minutes without an increase in
circuit capacity, an oil recovery routine is initiated. When this
routine is initiated, a second compressor in the circuit is started.
Once started, the normal capacity control routine takes priority
and will turn off the compressor if needed.
CONFIGURATION MODE
SUBMODE ITEM DISPLAY ITEM DESCRIPTION COMMENT
OPT1
RAT.T X RAT Thermistor Type
Default: 0
Range: 0 to 2
Must be set for appropriate value:
0 = 5 k:
1 = 10 k:
2 = None
SAT.T X SAT Thermistor Type
Default: 0
Range: 0-2
Must be set for appropriate value:
0 = 5 k:
1 = 10 k:
2 = None
OPT2 C.TYP X Machine Control Type
Default: 4
Range: 1 to 9
Set Item to 1 (VAV)
SETPOINTS MODE
COOL CSP.1 XX.X Cooling Setpoint 1
Range: 40.0 to 80.0 °F (4.4 to 26.7 °C)
Default: 60.0 °F (15.6 °C)
RAT — Return Air Thermistor
SAT — Supply Air Thermistor
VAV — Variable Air Volume
CONTROL MODE
STAT
INDOOR
FAN
STATUS
CIR A
ID.F.A
SPACE TEMPERATURE
CONTROL MODE
SPT.M
1 (Off Local) Off or On 0 (Cool Off)
2 (Off CCN) Off or On 0 (Cool Off)
3 (Off Time) Off or On 0 (Cool Off)
4 (Off Emrgcy) Off or On 0 (Cool Off)
5 (On Local) On 3 (Cool On)
6 (On CCN) On 3 (Cool On)
7 (On Time) On 3 (Cool On)
8 (IDFS Not On) Off 3 (Cool On)
9 (SPT Satisfied) Not Applicable