48 18-CD30D1-20-EN
Installer’s Guide
the 40% manifold pressure. This will insure that the
learning routine is complete and that the heat rise is
stable.
j. Read the 40% manifold pressure.
k. If needed, remove the low heat manifold adjustment
cover and adjust to obtain the correct manifold pres-
sure. See Figure 59.
40% (LOW) HEAT ADJUSTMENT: TURN CLOCKWISE TO DE-
CREASE MANIFOLD PRESSURE OR COUNTERCLOCKWISE TO
INCREASE MANIFOLD PRESSURE.
l. Use Manifold Pressure Settings Table 21 for the correct
manifold pressure setting in Inches of Water Column.
m. Once the 40% manifold pressure has been adjusted;
push the Enter button on the user interface. This will
stop the gas valve setup mode and take you back to
the home screen.
3) Setting “MAX” manifold gas pressure
To enter the Gas Valve Setup mode:
a. Scroll down on the user interface to Unit Test.
b. Scroll to the right and select “Gas Val Setup”.
c. Push the Enter button.
d. Scroll to the right and select MAX; then push the Enter
button.
e. Select “MAX” and push the Enter button.
f. When asked “Are You Sure”, select Yes, and push the
Enter button.
g. The furnace will now begin another ignition sequence.
h. If pressure switch 2 & 3 learning routines have not
been performed; after successful ignition, the inducer
will go through this operation. (see Inducer Learning
Routine section).
i. Allow 5 minutes to pass before attempting to adjust
the 100% manifold pressure. This will insure that the
learning routine is complete and that the heat rise is
stable.
j. Read the 100% manifold pressure.
k. If needed, remove the high heat manifold adjustment
cover and adjust to obtain the correct manifold pres-
sure. See Figure 59.
100% (HIGH) HEAT ADJUSTMENT: COUNTERCLOCKWISE TO
DECREASE MANIFOLD PRESSURE OR CLOCKWISE TO IN-
CREASE MANIFOLD PRESSURE.
l. Use Manifold Pressure Settings Table 22 for the correct
manifold pressure setting in Inches of Water Column.
m. Replace and tighten the adjustment cover for the high
heat and read the manifold pressure again. This
procedure may need to be repeated until the correct
manifold pressure is obtained.
NOTE: The adjustment cover over the high heat must
be in place during manifold gas pressure readings.
See Figure 53.
n. If the firing rate cannot be obtained with the manifold
pressures specified in Table 22, the orifices must be
changed. If a change of orifices is required to correct
the furnace input rating, refer to Table 17 on page 37.
o. Once the 100% manifold pressure has been adjusted;
push the Enter button on the user interface. This will
stop the gas valve setup mode and take you back to
the home screen.
s
s
WARNING
!
EXPLOSION HAZARD
REPLACE AND/OR TIGHTEN ALL PLUGS REMOVED OR
LOOSENED WHEN ADJUSTING GAS PRESSURE. LEAK CHECK
THE FITTINGS BEFORE PLACING INTO REGULAR SERVICE.
FAILURE TO FOLLOW THIS WARNING COULD RESULT IN
SERIOUS PERSONAL INJURY, PROPERTY DAMAGE, OR
DEATH.
p. Remove all field supplied tubing and measurement
devices. Reinstall and tighten all covers and outlet
pressure tap screw.
q. Leak test all gas fittings using a leak detection solution
or soap suds.
r. Turn comfort control to home owners desired
temperature.
