To measure CO
2
levels in the Keston boiler remove the 1/8" plug from the flue outlet pipe spigot
(Figure 6.7.4 item 17). Insert the probe of a calibrated combustion analysis meter and sample the
gases as instructed in the test equipment's instructions.
When firing the boiler for the first time since installation, the CO level at high rate may be between
100 & 220 ppm and between 50 & 80 ppm at low rate. This is due to compounds used during
manufacture curing within the combustion chamber. On boilers which have been fired for more than
one hour since installation, the CO levels should not exceed 150 ppm at high rate and 50 ppm at low
rate. If CO levels above these values are experienced, the combustion chamber and flue system
should be investigated.
The Qudos 28s is factory set for combustion and should need no adjustment. However, in the
event adjustment is required.
Check combustion errors are not a result of incorrectly installed flue and/or air system, terminal
location or damage or debris on the burner. If all these factors are found to be in order precede as
follows:
1) Set any controls to call for heat.
2) Press the “
” button repeatedly until the display shows “SEr”, then press “ENTER”. Press
the “
” until the display shows “100%”. Press “ENTER” and the boiler will be locked on at Maximum
rate. If no further buttons are pressed for 10 minutes the boiler will automatically revert to normal
operation.
3) Measure the CO
2
reading in the flue gases and adjust, if necessary, the adjustment screw
(pos 4) to produce a CO
2
reading of 8.9 - 9.3% with a corresponding CO level of 50 - 150 ppm.
4) Press the “RESET” button once and then press the “ENTER” button. Use the “
” button until
the display shows “32%”. Press the “ENTER” button and the boiler will be locked on at Minimum rate.
If no further buttons are pressed for 10 minutes the boiler will automatically revert to normal operation.
5) Measure the CO
2
reading in the flue gases. The CO
2
reading must be 8.4% to 8.8% with a
corresponding CO level of 5 to 20 ppm for natural gas. THE CO
2
LEVEL AT LOW RATE MUST
ALWAYS BE LESS THAN THE CO
2
LEVEL AT HIGH RATE.
6) Press the “RESET” button once and then use the “
” button until the display shows “100%”.
Press the “ENTER” button and the boiler will be locked on at Maximum rate. Check the setting is
within the range established in step 3. If not, repeat the process again from step 3.
If following the above procedure, combustion levels described above at both high and
low rate could not be obtained, please turn off the appliance and isolate the gas to the appli-
ance. Telephone KESTON BOILERS technical support (phone no. 0208 462 0262)
8) Press the “RESET” button twice to return to the normal operation mode and display.
vi)
Note the original appliance serial number band production date on the new data badge
vii)
Stick the new data badge Q.10S.1.00.04.0 ( for the Qudos 28s - Fig. 6.7.4 item 8) or
Q.10H.1.00.03.0 (for the Qudos 28h - Fig. 6.7.4 item 7) into the appliance in place of the
original NG database.
viii)
Reassemble (Section 8.3).
Keston Condensing Boilers NG Specifications
Supply pressure:
High
25 mbar
Normal
20 mbar
Low
17 mbar
WD480/0/2008
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