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▶ If the manometer reading is in the white area of the chart the heat
exchanger/exhaust path/condensate trap does not require
attention.
▶ If the manometer reading is in the black area of the chart then carry
out the following checks:
– Check that the condensate trap is not blocked.
– Check the exhaust paths for restrictions.
– Clean the heat exchanger with a suitable cleaning tool, refer to
section 6.7.4 - Cleaning the heat exchanger.
▶ Re-check the fan pressure readings.
If the boiler, after completing the above checks, fails the fan pressure
test then contact Worcester, Bosch Group for advice.
▶ After the measurements are taken switch the boiler off.
▶ Disconnect the manometer and replace the test point cover.
6.5
Checking the flue integrity
The appliance combustion cover must be fitted whilst
this test is being performed.
Refit the test point caps after the test has been
performed.
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 47.
▶ With the combustion cover fitted and the appliance running at
maximum output for at least 10 minutes, remove the cap from the air
inlet sample point [2]
▶ Attach the analyser probe to the sample point
▶ Allow the readings to stabilise and check that:
– O
is equal to or greater than 20.6%
2
– CO
is less than 0.2%
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
Ensure that the gas inlet pressure is correct before
continuing, refer to section 5.5.1
Combustion test:
▶ Remove cap on the flue gas sample point [1], as shown in figure 47
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 CO/CO
table 15 - CO/CO
settings, on page 37
2
▶ Turn the temperature control down to minimum and allow the boiler
to stabilise for ten minutes
▶ Check the CO/CO reading for minimum output against those in
table 15 - CO/CO
settings, on page 37
2
6720818077 (2016/04) -
Greenstar Highflow CDi
readings against those in
2
ErP
1
Fig. 47 Flue integrity test
[1]
Flue gas sample point
[2]
Combustion air sample point
If the boiler fails the combustion test, check the following possible
causes:
1. Refer to section 5.5.1 and check the gas inlet pressure
2. Confirm the correct fan pressure.
3. Air intake for restrictions.
4. Check the diaphragm in the fan for damage, replace if damaged.
5. Check the diaphragm for correct operation, the diaphragm opens
towards the fan.
6. Cleanliness of the heat cell, plus blockages in the condensate
disposal.
6.7
Heat exchanger
6.7.1
To clean the burner
WARNING: Burner
▶ Do not remove the burner unless a new burner head
gasket is available for re-assembly.
▶ 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.
SERVICING AND SPARES
2
33
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