43
A = air probe
B = flue gases probe
C = O-ring gaskets
D = probes cap
E = fixing screw
Figure 38
- Combustion
analysis probes
11 - OPERATING
11.9 - Checking and
adjusting CO2
levels
Section 14 lists the correct CO2
ranges for a boiler running at normal
operating conditions at an altitude
below 3000 ft
(1000m)
. CO2 values
outside of the ranges given in section
14 may lead to malfunctioning of the
boiler and cause it to prematurely fail.
To check the CO2 value, carry out a
combustion analysis as follows while
referencing figure 38:
carefully remove items “E”, “D” and
“C” from the combustion air/ vent
fitting:
generate a call for heat or, if this is
not possible, fully open a hot water
faucet;
press the
and
keys
for more than 10 seconds, the
display will show a blinking
;
press the
key until the
display shows
if a call for heat
has been generated or until
is
displayed if a domestic hot water
demand has been generated. The
boiler will now run for 10 minutes at
low fire input.
wait 2 to 3 minutes for the CO2 to
stabilize;
insert the probe of a calibrated
combustion analyzer into port “B”
and take a flue gas sample;
compare the CO2 reading with the
low fire range given in section 14
making sure to use the range for the
gas type in use. If the CO2 reading
is outside the specified range, it
must be adjusted.
To adjust the CO2 proceed as follows:
use a screwdriver to remove the gas
valve cap, item “F” in figure 35;
turn the regulator screw found under
cap “F” clockwise to increase the
CO2, counter-clockwise to decrease
the CO2;
turn the regulator screw in small
increments and wait for the CO2 to
stabilize to prevent overshooting the
desired value:
replace the gas valve cap, item “F” in
figure 35;
seal screw “F” with red paint or nail
polish to discourage tampering.
press the
key until the
display shows
if a call for
heat has been generated or until
is displayed if a domestic hot
water demand has been generated.
The boiler will now run for 10
minutes at high fire input;
wait 2 to 3 minutes for the CO2 to
stabilize;
insert the probe of a calibrated
combustion analyzer into port “B”
and take a flue gas sample;
compare the CO2 reading with the
high fire range given in section 14
making sure to use the range for the
gas type in use. If the CO2 reading
is outside the specified range, it
must be adjusted.
To adjust the CO2 proceed as follows:
use a screwdriver to turn screw “E”
shown in figure 35;
turn screw “E” clockwise to reduce
the CO2, counter-clockwise to
increase the CO2;
turn screw “E” in small increments
and wait for the CO2 to stabilize to
prevent overshooting the desired
value:
seal screw “E” with red paint or nail
polish to discourage tampering.
press the
button to return the
boiler to its normal operating mode.
NOTE: During the 10 minutes
override mode, error code L06 may
appear if the demand on the boiler
is low causing the flue gas
temperature to increase rapidly,
see section 12.12.1.
11.9.1 - Checking
and adjusting CO2
levels without CO2
meter
The ionisation current value is directly
related to the CO2 value. Therefore,If
you are not in possession of a CO2
meter, you can use the ionisation
current value to correctly adjust the
CO2 value.
To do so, follow exactly the step of
section 11.9 and instead of comparing
the CO2 value you must compare the
right side of the display (ionisation
current value) with the corrisponding
“ionisation current” value in section 14.
Because the reading of the ionisation
current is not a fixed value but can vary
±
3, you must compare the average
value of the fluctuation, with the value
in section 14 (see also section
13.13.4).
Summary of Contents for ONEX
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