Inspection and maintenance
Worcester 2000 – 6 721 814 551 (2019/09)
52
9.4 Fan pressure test
NOTICE:
Fan pressure test
▶ The appliance must be running at maximum output in chimney sweep
mode for the fan pressure test, ( Setting the appliance to
maximum).
This test is to determine if the heat exchanger requires cleaning or
additional actions.
Fan pressure test reading.
▶ The pressure reading will be in negative values.
9.4.1 Checking heating block
▶ Remove the front casing.
▶ Remove the cap from the test nipple, and connect a pressure gauge.
Fig. 61 Test nipple at the mixing device
Appliance fan pressure test values
Natural Gas appliances
Table 28 Natural Gas values
If the manometer reading is within tolerance, in the white area of the
table values.
▶ The heat exchanger/exhaust path/siphon does not require attention.
If the manometer reading is out of tolerance, in the shaded area of the
table values then carry out the following checks.
▶ Check that the siphon is not restricted or blocked.
▶ Check the exhaust paths for restrictions.
▶ Clean the heat exchanger with a suitable cleaning tool, refer to
cleaning section.
▶ Re-check the fan pressure readings.
If the appliance, after completing the above checks, fails the fan
pressure test then contact Worcester, Bosch Group for advice.
▶ Switch the appliance off after completing pressure check.
▶ Disconnect the digital manometer and replace the test point cover.
▶ Replace the combustion air intake pipe after completing pressure
check.
9.5 Check working gas inlet pressure
NOTICE:
Gas inlet pressure
▶ Do not continue with the other checks if the correct gas inlet pressure
can not be achieved.
▶ Check the gas supply working pressures in the system conform to the
readings shown in the table shown in section 6.6 "Checking gas inlet
pressure".
9.6 Flue gas analysis
NOTICE:
Combustion testing
▶ Combustion testing must be carried out by a competent person.
Testing must not be attempted unless the person carrying out the
combustion check is equipped with a calibrated flue gas analyser
conforming to BS 7967 and is competent in its use.
Flue gas analysis
▶ Ensure that the gas inlet pressure has been checked and is
satisfactory.
▶ Refit the test point plugs after the test has been completed.
▶ Set the appliance to maximum and minimum output in chimney
sweep mode ( 6.5 "Chimney sweep mode") for the flue gas
analysis checks.
▶ Check that the readings conform to those given in the following
tables. In addition to CO and CO/CO
2
ratio checks also check the
maximum and minimum CO
2
percentage reading.
Appliance combustion contents settings
Table 29 CO
2
and O
2
settings
If the CO
2
is out of tolerance then please check:
▶ The gas inlet pressure.
▶ The gas rate.
▶ The fan test pressure.
▶ The flue and air intake, plus any possible blockages in the condensate
disposal.
▶ The condition of burner.
▶ For leaks or obstructions in the exhaust paths.
▶ That the injector is clean.
After all checks have been completed and the CO
2
is still out of tolerance
then contact Worcester, Bosch Group helpline 0330 123 3366.
Appliance
output
Cleaning required No cleaning required
Value
30kW 0 mbar -4.7 mbar -4.8 mbar -12 mbar
25kW
0 mbar -3.2 mbar -3.3 mbar -12 mbar
0010015926-001
CO
2
Reading CO Reading O
2
Reading
Natural Gas - Maximum rated Output
1)
1) Should be measured 10 minutes after firing the appliance
Between 9.0 and 10.8% <250ppm 4.0 %
Natural Gas - Minimum rated Output
1)
A minimum of 0.6 lower than the
maximum reading taken but above 8.2%
<250ppm 5.5 %
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