PAGE 11
INSTALLER’S GUIDE
1
1
2
2
M9097
ENTHALPY CHANGEOVER
SETPOINT
LED LIGHTS WHEN
OUTDOOR AIR IS SUITABLE
FOR FREE COOLING
INSERT DC MILLIAMMETER BETWEEN SO AND S FOR CHECKOUT
AND TROUBLESHOOTING.
JUMPER USED FOR SINGLE ENTHALPY CONTROL.
TR
TR1
A
B
C
D
SO
SR
+
+
+
C7400
620 OHM
JUMPER
DC
MILLIMETER
W7459
S
+
1
1
M9098B
ENTHALPY
CHANGEOVER
SETPOINT
MINIMUM
DAMPER
POSITION
SETTING
LED LIGHTS
WHEN OUTDOOR
AIR IS SUITABLE
FOR FREE COOLING
MINIMUM DAMPER POSITION ADJUSTMENT
IS PRESENT ONLY ON W7459A,D MODELS.
Meter Location for Checkout and Troubleshooting
Location of Enthalpy Set Point, Minimum Posi-
tion and LED
Table 2. Enthalpy Checkout Procedure
Figure 13. Enthalpy LEDs and Checkout
Checkout Procedure
Response
A
1. Disconnect power at TR and TR1.
2. Disconnect jumper P to P1.
3. Jumper TR to 1.
4. Jumper T1 to T.
5. If connected, remove C7400 Solid State Enthalpy Sensor
from teminals S0 and +. Ensure factory-installed 620 ohm
resistor is connected to terminals Sr and +.
6. Apply power (24Vac) to terminals TR and TR1
LED is off.
Motor is in closed position.
B
1. Disconnect factory-installed 620 ohm resistor from
terminals Sr and +.
Led turns on, motor drives toward open.
C
1. To simulate high and low enthalpy (single enthalpy
sensor) reconnect factory-installed 620 ohm resistor from
termonals Sr and +. Connect 1.2K ohm 4074EJM Checkout
Resistor across terminals So and +.
__
2. Turn enthalpy setpoint potentiometer to "A".
LED turns on, indicating low enthalpy.
Motor drives toward open.
3. Turn enthalpy setpoint potentiometer to "D".
LED turns off, indicating high enthalpy.
Motor drives toward closed.
4. Disconnect the 1.2 K ohm checkout resistor.
__
D
1. To verify sensor operation, reconnect the + lead of the
outdoor enthalpy sensor to the + terminal of W7459.
__
2 Connect a DC millimeter between terminal So of the
W7459A and terminal S of the enthalpy sensor. See Fig. 10
(positive meter lead to terminal S of the enthalpy sensor).
Millimeter indication is between 3 and 25
mA if sensor is operating properly.
If millimeter indicates zero, the sensor may
be wired backward.
3. When using differential enthalpy, check the return air
enthalpy sensor by connecting a DC millimeter between
terminal Sr of the W7459A and terminal S of the return air
enthalpy sensor. (positve meter lead to terminal S of the
enthalpy sensor).
Millimeter indication is between 3 and 25
mA if sensor is operating properly.
If millimeter indicates zero, the sensor may
be wired backward.
