Servicing
5
46
Installation and maintenance instructions for wall-mounted condensing gas boiler 600 - 28C • 01/2004
Subject to modifications resulting from technical improvements!
Boulter Buderus Ltd. • http://www.boulter-boilers.com
5.3
Checking and replacing parts
5.3.1
Checking and replacing the flue gas sensor
z
Shut the boiler down by setting the mains switch to "0".
z
Remove the casing.
z
Remove the ventilation cover.
z
Remove both plugs from the flue gas thermostat
(see fig. 58, item 1).
z
Measure the resistance of the flue gas thermostat
(see fig. 59).
z
Measure the temperature of the flue gas. Compare the
outcome to the measured resistance using the table below.
z
Remove the UBA 3 (see fig. 60) to test the cable's resist-
ance (see fig. 61).
z
Remove the flue gas sensor when necessary by turning it
to the left.
z
Install the new flue gas sensor in reverse order.
fig. 58 Remove plugs from flue gas thermostat
1
fig. 59 Measure flue gas thermostat resistance
Flue gas thermostat
Temperature
Position
Resistance in
Ω
≤
105 °C
open
0
> 105 °C
closed
endless high
Table 10 Flue gas thermostat
fig. 60 Remove UBA 3
