Operating Sequences; Staged Air Volume (3- - Speed) Fan Motor; W7220 Economizer Control; Base Unit Controls - Carrier WeatherExpert 50LC Installation Instructions Manual

4-1/4 (108)
2-3/4 (70)
NOTE: Dimensions are in inches. Dimensions in ( ) are in mm.
Fig. 52 - - Enthalpy Control Sensor, Dimensions and
DIP Switch Location
Table 11 – Enthalpy Control Sensor
Wiring Terminations*
Terminal
Type
Nbr Label
1 S--- BUS S--- BUS
2 S--- BUS S--- BUS
* Terminals are polarity insensitive.
Table 12 – Enthalpy Control Sensor DIP Switch Settings
DIP Switch Positions for Switches 1, 2, and 3
Use
1
DA OFF
RA ON
OA OFF
Legend
DA = Discharge Air
RA = Return Air
OA = Outside Air
When a S- - bus sensor is connected to an existing network,
it will take 60 minutes for the network to recognize and
auto- - configure itself to use the new sensor. During the 60
minute setup period, no alarms for sensor failures (except
SAT) will be issued and no economizing function will be
available.

Operating Sequences

Staged Air Volume (3- - Speed) Fan Motor —
The Integrated Staging Control (ISC) Board in the main
unit determines the operating speed (LOW/MED/HIGH)
of the indoor fan based on space thermostat demand
conditions. See Table 13 for this logic.
51/64 (21)
2-1/64 (55)
a50--- 9614
Description
S--- Bus Communications
(Enthalpy Control Sensor Bus)
S--- Bus Communications
(Enthalpy Control Sensor Bus)
2 3
ON OFF
OFF OFF
OFF OFF
Table 13 – Supply Fan Speed Logic without Economizer
TSTAT
OUTPUT
G/OCC 0--- V
Y1 0--- V
Y2 0--- V
Y3 0--- V
W1 0--- V
W2 0--- V
SUPPLY
FAN
OFF
MOTOR
SPEED
W7220 Economizer Control —
Tables 14 and 15 provide the W7220 Input/Output Logic.
Table 14 describes economizer functions for a unit
without a CO sensor. Table 15 describes economizer
2
functions for a unit with Demand Controlled Ventilation
(CO sensor connected). The supply fan speed is included
2
in these tables for reference; this is neither an input or
output of the W7220 controller.
Base Unit Controls —
Base unit includes standard electromechanical controls,
Staged Air Volume (3- - speed supply fan motor with VFD),
R
EconoMi$er X (with W7220 controller) and thermostat
or unitary controller that energizes the G terminal in
cooling and heating to control the supply fan operation.
Cooling, Unit With EconoMi$er X Without CO
Sensor —
For Occupied mode operation of the EconoMi$er X
control, there must be a 24- - v signal at terminal G at the
unit's Integrated Staging Control Board from the
thermostat; supply fan motor will start and run in Low
Speed. The signal at G is connected to W7220 input OCC,
placing the EconoMi$er X control in Occupied mode; the
economizer actuator is commanded open to the MIN POS
L ventilation position. Removing the signal at OCC places
the EconoMi$er X control in Unoccupied mode; the
economizer actuator is driven back to full- - closed position.
When free cooling using outside air is not available, the
unit cooling sequence will be controlled directly by the
space thermostat. Thermostat call for Stage 1 Cooling
energizes ISC terminals G and Y1; supply fan motor starts
and runs in Low Speed. The Y1 demand is received at
W7220 terminal Y1- - I. Outside air damper position will be
at MIN POS L. W7220 output Y1- - O is energized; first
stage mechanical cooling starts.
As space temperature falls and space cooling load is
satisfied, the thermostat will remove its call for first stage
cooling; ISC terminal Y1 call is removed. The W7220
input Y1- - I is removed; output Y1- - O is de- - energized,
stopping first stage cooling.
When ISC terminal Y1 is de- - energized, terminal G may
remain energized, indicating Continuous Fan operation.
40
24---V 0--- V 0--- V
24---V 0--- V 0--- V
0--- V 24---V 0--- V
0--- V 0--- V 24---V
0--- V 0--- V 24---V
0--- V 0--- V 24---V
LOW MED HIGH
2