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Maintenance and service
29
adjusting CO
2
until pressure is at or above these levels,
but not to exceed 10.5” WC for Natural Gas and 13”
WC for Propane.
A. Once Gas Pressure is adequate
B Press ON/OFF button to turn off the heater.
B Remove brass flat head screw on the exhaust collar
as seen in Fig. 53.
B Insert CO
2
analyzer probe into the measuring port.
The tip of the probe should be in the center of the flue
pipe (approx 1.5" inserted). Avoid air gaps between
probe and measuring port as they can alter readings.
Fig. 53 Measuring port
B While holding the Program (P) button in, press the
ON/OFF button to turn ON the heater (see Fig. 54).
As soon as ‘188’ flashes on the display, release the
Program button. The display should now read P2.
Press button until “P1” appears on display.
Fig. 54
B. Measuring CO
2
(combustion cover must be
installed):
B Open all hot water taps to achieve a flow rate of at
least 6 gallons per minute. (1 tub and 2 sinks should
be sufficient). If heater display reverts to P2, open
more hot water fixtures to allow sufficient flow. Press
‘ ’ until P1 reappears on the display.
B Record the CO
2
reading in P1 below. (Analyzer
reading may take several minutes to stabilize).
B Press the ‘ ’ button until P2 appears. Unit will
ramp down to low fire and the flow should decrease.
B Record the CO
2
reading in P1 and P2 below.
P2 CO
2
Reading: % CO
2
P1 CO
2
Reading: % CO
2
C. Adjusting CO
2
:
Note: P1 adjustment will change the P2 reading.
Confirm the P1 value BEFORE adjusting the P2 level.
1. If P1 CO
2
level is off:
B Loosen yellow painted philips screw (1) and cover
should rotate down (2) revealing a recessed brass
slotted screw. Fig. 55.
B Turning the slotted screw counter clockwise will
raise P1 CO
2
levels and clockwise will lower P1
CO
2
levels. Adjustments to the slotted screw will
also change P2 CO
2
levels.
B After bringing the P1 CO
2
readings in proper range,
press the button to enter the P2 mode. Verify
CO
2
readings in P2 mode.
2. If P2 CO
2
level is off:
B Remove yellow painted #40 Torx cover from the front
of the gas valve. (Fig. 56) A plastic #40 Torx screw
will be revealed.
B Turning the plastic #40 Torx screw counter
clockwise will lower P2 CO
2
levels and clockwise
will raise P2 CO
2
levels.
Note: This screw adjustment is very sensitive and
should be made in small increments. It may take several
minutes for readings to stabilize.
3. Verify both P1 and P2 CO
2
readings are within the
ranges specified in table 14. Repeat steps 1 and 2 as
necesssary until CO
2
values are within the specified
ranges.
4. Once CO
2
values are within the specified ranges,
verify the CO readings on P1 and P2 do not exceed
values shown in table 14. If values exceed this limit,
inspect vent system and fin coils (chapter 6.1, page 27)
for blockage.
D. Returning to Service:
1. Return slotted screw cover to original position and
tighten philips screw.
2. Reinstall Torx cover.
3. Remove CO
2
analyzer probe and reinstall flathead
screw with gasket in exhaust collar.
4. Press ON/OFF button to turn OFF the heater and
then turn ON the heater.
5. Heater is ready for normal operation.