SERVICING AND SPARES
Greenstar FS CDi
ErP
6720818079 (2016/04)
31
6.5
Checking the flue integrity
The integrity of the flue system and performance of the appliance can be
checked via the sample points at the top left hand side of the combustion
chamber, refer to figure 44.
▶ With the combustion cover fitted and the appliance running at
maximum output, remove the cap from the air inlet sample point [1]
▶ Insert the analyser probe into the sample point
▶ Allow the readings to stabilise and check that:
– O
2
is equal to or greater than 20.6%
– CO
2
is less than 0.2%
▶ If the readings are outside these limits, then this indicates that there
could be a problem with the flue system or combustion circuit.
6.6
Flue gas analysis
Combustion test:
▶ Remove cap on the flue gas sample point [2], as shown below and
connect a flue gas combustion analyser. Replace the cap after use.
▶ Press the Service engineer button for more than 10 seconds
▶ Turn the temperature control to maximum and the boiler will go to
maximum output
▶ Run the boiler at maximum output for at least 10 minutes
▶ After 10 minutes, check the maximum CO/CO
2
readings against the
information in table 13 on page 35
▶ Turn the temperature control down to minimum and allow the boiler
to stabilise for 10 minutes
▶ After 10 minutes, check the minimum CO/CO
2
readings against the
information in table 13 on page 35
Fig. 44 Flue integrity test
[1]
Air inlet sample point
[2]
Flue gas sample point
If the boiler fails the combustion test, check the following possible
causes:
▶ Refer to section 5.5.1 and check the gas inlet pressure
▶ Confirm the correct fan pressure.
▶ Air intake for restrictions.
▶ Check the diaphragm in the fan for damage, replace if damaged.
▶ Check the diaphragm for correct operation, the diaphragm opens
towards the fan.
▶ Cleanliness of the heat cell, plus blockages in the condensate
disposal.
6.7
Heat exchanger
6.7.1
To clean the burner
▶ Check that the boiler is completely isolated from the gas supply.
▶ Disconnect the mixing chamber from the fan.
▶ Remove the connector and earth wire from the fan.
▶ Remove the clips [1], castellated nuts[2a] and springs [2b] from the
studs [2].
▶ Remove the rear nut [4a] from the rear stud [4].
▶ Remove the burner cover plate [5] and fan [7] from the top of the
heat exchanger.
▶ Remove the burner [6] and clean the components.
Do not use a wire brush.
Fig. 45 Burner removal
6.7.2
To check the flap valve in the fan intake
▶ Refer to section 6.9.3 on page 36 for access to the fan intake.
▶ Carefully withdraw the flap valve from fan intake tube and check for
soiling and splits, clean or replace as required.
▶ Take care when refitting the flap valve, the flaps must open upwards
into the fan intake tube.
▶ After re-assembly check CO/CO
2
levels as described in the section
“Setting the air/gas ratio” on page 34.
The appliance combustion cover must be fitted whilst
this test is being performed.
Refit the test point caps after the test has been
performed.
Ensure that the gas inlet pressure is correct before
continuing, refer to section 5.5.1
6720648568-40.1W
o
2
1
WARNING:
Burner
▶ Do not remove the burner unless a new burner head
gasket is available for re-assembly.
6720818079-25.1W
o
2
4
6
8
5
7
2a
2b
1
4a
