Maintenance and service
830 ES – 6 720 644 936 (2021/08)
54
CO
2
adjustment is required in Natural Gas installations where
energy content is less than 900 BTU/cuft, and in installations
with repeated unresolved EA and EC errors (ref. to chapter 9
“Problem solving”).
CAUTION:
▶ One factor that may affect CO
2
levels is improper gas
pressure. Please see chapter 4.14 for the procedure to
measure gas pressure and record your findings below:
Static Gas Pressure: “ WC
P1 Operating Pressure: “ WC
The P1 minimum operating gas pressure is 3.5" WC for Natural
Gas and 8" WC for Propane. Do not proceed in 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
▶ Press ON/OFF button to turn OFF the heater.
▶ Remove brass flat head screw on the exhaust collar as seen
in fig. 60.
▶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. 60 Measuring port
▶ Push and hold the button.
▶ Turn power back on by pushing the power button .
▶ Continue to hold the button until all symbols on the
screen light up and the temperature reads 188 °C.
▶ When display reads 188, immediately release the
button.
The display should now read P2.
▶ Press button until “P1” appears on display.
B. Measuring CO
2
(Combustion cover Installed):
▶ 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 back to P2, open more hot water
fixtures to allow sufficient flow. Press + until P1 reappears
on the display.
▶Record the CO
2
reading in P1 below. (Analyzer reading may
take several minutes to stabilize).
▶ Press the ‘+’ button until P2 appears. Unit will ramp down to
low fire and the water flow should decrease.
▶Record the CO
2
reading in P2 below.
P1 CO
2
Reading: % CO
2
P2 CO
2
Reading: % CO
2
Note: When making adjustments, make sure combustion cover
is installed.
Table 36 CO & CO target numbers
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:
▶ Loosen yellow painted Phillips screw (1) and cover should
rotate down (2) revealing a recessed brass slotted screw,
fig. 61.
CO
2
range (%) Max. CO level
(measured)
Nat. Gas
max. input P1 6.3 % - 6.9 % < 250 ppm
min. input P2 2.3 % - 2.6 % < 60 ppm
LP Gas
max. input P1 8.3 % - 8.9 % < 250 ppm
min. input P2 2.6 % - 2.9 % < 60 ppm
* Values above are for climate controlled conditions.
Inputs such as gas pressure, heating value of the gas,
humidity and temperature of combustion air all impact CO
and CO
2
values. Changes in these inputs can result in
different CO and CO
2
values on the same appliance.
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