Controls Quick Start; Variable Air Volume Units Using Return Air Sensor Or Space Temperature Sensor; Multi-Stage Constant Volume Units With; Mechanical Thermostat - United Technologies Carrier Weathermaker 48A2 Controls, Start-Up, Operation, Service, And Troubleshooting

UNIT
50A2,A3020
50A4,A5020
50A2,A3025
50A4,A5025
50A2,A4027
50A3,A5027
50A2,A4030
50A3,A5030
50A2,A4035
50A3,A5035
50A2,A4040
50A3,A5040
50A2,A4050
50A3,A5050
50A2,A4060
50A3,A5060
*Operation at these levels may be limited by entering evaporator air wet bulb temperatures.

CONTROLS QUICK START

The following section will provide a quick user guide to set-
ting up and configuring the A Series units with ComfortLink
controls. See Basic Control Usage section on page 4 for infor-
mation on operating the control. For wiring information, refer
to unit wiring diagrams in the Major System Components sec-
tion on page 103.
IMPORTANT: The ComfortLink controls provide the user
with numerous configuration options such as setpoints,
demand levels, reset, and many others. If the building
owner or design engineer has not provided specific recom-
mendations for these configuration settings, it is suggested
that the installer does not make changes to the default fac-
tory settings. The factory-configured default values are
appropriate for many applications.
IMPORTANT: The unit is shipped with the unit control
disabled. Enable the control by setting Local Machine

Disable (Service Test STOP) to No.
Variable Air Volume Units Using Return Air
Sensor or Space Temperature Sensor —
figure the unit, perform the following:
1. The type of control is configured under Configuration
 
UNIT C.TYP. Set C.TYP to 1 (VAV-RAT) for return
air sensor. Set C.TYP to 2 (VAV-SPT) for space tempera-
ture sensor.
NOTE: For VAV with a space sensor (VAV-SPT), under

Configuration UNIT
space sensor by setting SPT.S to ENBL.
2. Install jumpers between R-W2 and W2-W1 on TB4 in
the control box.
3. The space temperature setpoints and the supply air set-
points are configured under the Setpoints menu. The
heating and cooling setpoints must be configured. See the
Heating Control and Cooling Control sections for further
description on these configurations. Configure the
following setpoints:
OHSP Occupied Heat Setpoint
OCSP Occupied Cool Setpoint
UHSP Unoccupied Heat Setpoint
V.C.ON VAV Occupied Cool On Delta
V.C.OF VAV Occupied Cool Off Delta
SASP Supply Air Setpoint
Table 29 — Air Quantity Limits (50A2,A3,A4,A5)
COOLING
Min CFM
6,000
4,000
7,500
5,000
8,100
5,400
9,000
6,000
10,500
7,000
12,000
8,000
13,500
10,000
18,000
12,000
To con-
 
SENS SPT.S, enable
Max CFM*
10,000
10,000
12,500
12,500
13,500
13,500
15,000
15,000
17,500
17,500
20,000
20,000
20,000
20,000
27,000
27,000
4. To program time schedules, make sure SCH.N=1 under
Configuration
the control to use local schedules.
5. Under the Timeclock
sired schedule. See Time Clock Configuration section on
page 77 for further description of these configurations.
6. Under Configuration
static pressure setpoint should be configured.
SP.SP
7. If supply air temperature reset is desired, under the
Configuration
points should be configured:
RS.CF
RTIO
LIMT
RES.S
NOTE: Configure either RTIO and LIMT or RES.S. All three
are not used.
8. See the Economizer Options section on page 22 for addi-
tional economizer option configurations.
9. See the Exhaust Options section on page 22 for additional
exhaust option configurations.

Multi-Stage Constant Volume Units with

Mechanical Thermostat —
form the following:
1. Under Configuration
the
(TSTAT MULTI).
2. Remove jumpers from R-W2 and W2-W1 on TB4 in the
control box. Connect thermostat to TB4.
3. Under the
configurations:
SA.HI
SA.LO
4. See the Economizer Options section on page 22 for
additional economizer option configurations.
5. See the Exhaust Options section on page 22 for additional
exhaust option configurations.
Multi-Stage Constant Volume Units with
Space Sensor —
following:
1. Under Configuration
(SPT MULTI).
21
ELECTRIC HEAT
Min CFM
6,000
10,500
15,000
  
CCN SC.OV SCH.N to configure

SCH.L submenu, enter the de-
 
SP SP.SP, the supply duct
Static Pressure Setpoint

EDT.R submenu, the following set-
EDT Reset Configuration
Reset Ratio (if RS.CF = 1 or 2)
Reset Limit (if RS.CF = 1 or 2)
EDT 4-20 mA Reset Input (if RS.CF = 3)
To configure the unit, per-
 
UNIT C.TYP, set C.TYP to 3
Setpoints menu, set
Supply Air Setpoint Hi
Supply Air Setpoint Lo
To configure the unit, perform the
 
UNIT C.TYP, set C.TYP to 5
Max CFM
15,000
20,000
27,000
the following