Table of Contents
Inspection and maintenance
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
Appliance
Cleaning required
output
-4.7 mbar -4.8 mbar -12 mbar
30kW
0 mbar
-3.2 mbar -3.3 mbar -12 mbar
25kW
0 mbar
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.
52
0010015926-001
No cleaning required
Value
▶ 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
maximum and minimum CO
2
Appliance combustion contents settings
CO
Reading
2
Natural Gas - Maximum rated Output
Between 9.0 and 10.8%
Natural Gas - Minimum rated Output
A minimum of 0.6 lower than the
maximum reading taken but above 8.2%
1) Should be measured 10 minutes after firing the appliance
Table 29 CO
and O
settings
2
2
If the CO
is out of tolerance then please check:
2
▶ 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
then contact Worcester, Bosch Group helpline 0330 123 3366.
Worcester 2000 – 6 721 814 551 (2019/09)
ratio checks also check the
2
percentage reading.
CO Reading O
Reading
2
1)
<250ppm
4.0 %
1)
<250ppm
5.5 %
is still out of tolerance
2
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