CO
2
% partial load
9.0 – 9.5
11.5 – 12.0
CO
2
% full load
8.5 – 8.8
15.5 – 11.0
C0 ppm partial load
<15
<20
C0 ppm full load
<50
<150
The measured CO
2
and Co values are for partial load (20%) and full load (100%) with
the casing removed. When the setting is correct press the flue emissions test button
once and the boiler will revert to normal operation.
31.1 Flue System Check
In order to examine the flue pipe sealing it is essential that an O
2
or CO
2
reading is taken
from the 8mm plastic pipe that should be positioned from the Grey Vent/Flue adapter led
down and through the bottom boiler plate.
The flue seal is satisfactory when the CO
2
value is no more than 0.2% and the O
2
value
no more than 20.6%
31.2
STB Test Button (Green).
This button is used to test the correct operation of the overheat thermostat (high limit
thermostat).
32. Diagnostics
32.1
Control panel
The control panel of the unit has a LCD screen displaying two lines of data. This screen
provides information about the operation of the boiler it displays operation messages
(non-flashing) and fault messages (flashing display).
The first line contains textual information on the operating status of the unit. It shows:
Table 16 – LCD Display
IDLE
This display shows that there is no heat
demand
CH OPERATION
The boiler is operating in central heating
mode
TAP WATER OPERATION
The boiler is operating to produce DHW
10MIN. PARTIAL LOAD
The boiler is operating in chimney sweep
mode for 10 minutes
In the following cases, there may be a heat demand, but the burner is not working, for
one of the following reasons:
