Checking And Replacing Parts - Boulter Buderus Benchmark 600-28C Installation And Servicing Instruction

5 Servicing
5.3

Checking and replacing parts

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