14
INSTALLER’S GUIDE
18-HE39D8-13A-EN
1
1
2
2
M9097
ENTHALPY CHANGEOVER
SETPOINT
LED LIGHTS WHEN
OUTDOOR AIR IS SUITABLE
FOR FREE COOLING
JUMPER USED FOR SINGLE ENTHALPY CONTROL.
TR
INSERT DC MULTIMETER BETWEEN S
O
AND S FOR CHECKOUT
AND TROUBLESHOOTING.
TR1
A
B C
D
SO
+
SR
+
+
C7400
620 OHM
JUMPER
DC
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.
MULTIMETER
Meter Location for Checkout and Troubleshooting
Location of Enthalpy Set Point, Minimum
Position and LED
Table 2. Enthalpy Checkout Procedure - W7459 Control
Figure 13. Enthalpy LEDs and Checkout
Checkout Procedure
Response
A
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. 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 ter-
minals S0 and +. Ensure factory-installed 620 ohm resistor is connect-
ed to terminals Sr and +.
6. Apply power (24Vac) to terminals TR and TR1
―
1. To simulate high and low enthalpy (single enthalpy sensor) re-
connect factory-installed 620 ohm resistor from terminals 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 1.2K 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 multimeter between terminal So of the W7459A and
terminal S of the enthalpy sensor. See Fig. 13 (positive meter lead to
terminal S of the enthalpy sensor).
Multimeter indication is between 3 and 25 mA if
sensor is operating properly.
If multimeter indicates zero, the sensor may be
wired backward.
3. When using differential enthalpy, check the return air enthalpy
sensor by connecting a DC multimeter between terminal Sr of the
W7459A and terminal S of the return air enthalpy sensor. (positive
meter lead to terminal S of the enthalpy sensor).
Multimeter indication is between 3 and 25 mA if
sensor is operating properly.
If multimeter indicates zero, the sensor may be
wired backward.
