5
DI RECT MOUNT ECONOMIZER OP ER A TION
GENERAL
This accessory economizer package is designed to save
energy costs by using outdoor air for cooling and
ventilation in place of mechanical cooling whenever
possible. The economizer continuously monitors indoor
and outdoor air conditions and compares them to a
user-selected setpoint to determine if free cooling is
available. The economizer utilizes a fully-modulating
damper actuator, which will control the outside air damper
and return air damper in order to maintain a factory-set
mixed air/discharge air temperature.
ACCESSORIES
(-)XRX-AV04 - Dual Enthalpy Upgrade Kit
For maximum energy savings, this upgrade kit will allow
the economizer to compare the outdoor air enthalpy to the
return air enthalpy, instead of a user-selected setpoint to
determine if "free cooling" is available. This Sylk Bus
Sensor is a combination temperature and humidity sensor
which is powered by and communicates on the two-wire
communication bus of the W7220 economizer logic
module. All OA (Outside Air) and RA (Return Air) sensors
are the same. Sensor must be set for the type of sensing
using the three DIP switches located on the sensor during
INSTALLATION.
Dip Switch Set ting
C1
C2
C3
Re turn Air Enthalpy Sen sor
ON
OFF
OFF
Out side Air Enthalpy Sen sor
OFF
OFF
OFF
(-)XRX-AR02 - Wall-Mounted Carbon Dioxide Sensor
For installations requiring Demand Control Ventilation
(DCV) based upon indoor air levels of carbon dioxide
(CO
2
). When the unit supply fan is running, the CO
2
sensor
modulates the outside air damper to maintain a
user-selected CO
2
level inside the occupied space.
Energy savings are achieved by not bringing in excessive
amounts of outdoor air when the indoor air conditions are
suitable. Energy savings can be substantial on buildings
with highly variable occupancy rates.
NOTE: The (-)XRX-AR02 has a default setting of a 2-10
Vdc output for a 500-1500 ppm CO
2
input. The W7220
economizer controller requires jumper pins on the
sensor to be relocated to provide a 0-2000 ppm input.
SW2
SW1
AN (ppm)
Re lay (ppm)
ON
ON
0 to 1000
1000
OFF
ON
0 to 2000
¬
1200
ON
OFF
500 to 1500
800
OFF
OFF
500 to 2000
1200
DIP SWITCH LABEL
DIP SWITCHES (3)
SYLK BUS 2 PIN *EURO"
CONNECTOR
SYLK BUS TERMINALS
(1 AND 2)
Wiring Schematic for (-)XRX-AR02
Note: Black & brown wire common.
O
FF
O
N
O
FF
O
N
OUT
AN
)C
u
rr
en
t
SW2
SW1
0
-1
0
0
%
2
0
-1
0
0
%
)V
ol
ta
ge
RXRX-AR02 NEW JUMPER POSITION
(-)XRX-BFF02C, (-)XRX-BFF02D, (-)XRX-BFF02Y
Power Exhaust Kit
For installations requiring more space static pressure relief
than can be obtained with the standard barometric relief
damper included with the economizer, a power exhaust kit
can be added.
