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SERVICE AND SPARES
When running at maximum output, and the water
temperature is 65°C or less, the boiler will operate both
the central heating and DHW circuits with the diverter
valve in the mid position. It will be necessary to run
sufficient water through the DHW circuit to ensure that
the boiler will not cycle on low heating demands.
This is to allow sufficient time for the setting procedure.
When the water temperature reaches 75°C the diverter
valve will switch to CH only.
7.5.2 Fan pressure
▶ Remove the combustion air intake pipe [1]
▶ Remove the cover [2] from the fan pressure test point [4]
▶ Connect the pipe [3] from the digital manometer to the fan pressure
test point [4]
▶ Refit the combustion air intake pipe
1
4
3
2
Fig. 69 Fan pressure test point
NOTICE: Fan pressure test
▶ The boiler must be run at maximum output for the
fan pressure test and flue gas analysis.
With the combustion air intake pipe fitted and the boiler running at
maximum output, measure the fan pressure:
▶ The pressure will read negative, refer to the chart in figure 70 below.
FAN PRESSURE TEST
Clean the Heat Ex.
NG Boilers
36kW:
32kW:
- 3.5
28kW:
0
-1
-2
-3
LPG Boilers
36kW:
32kW:
28kW:
- 3.5
0
-1
-2
-3
Fig. 70 Fan pressure readings
▶ If the manometer reading is in the white area of the chart the heat
exchanger/exhaust path/siphon 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 siphon is not blocked.
44
Heat Ex. ok
- 5.4
- 4.4
-4
-5
-6
-7
-8
mbar
- 5.4
- 4.4
-4
-5
-6
-7
-8
mbar
– Check the exhaust paths for restrictions.
– Clean the heat exchanger with a suitable cleaning tool, refer to
section 7.7 - 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.
▶ Remove the combustion air intake pipe.
▶ Disconnect the manometer and replace the test point cover.
▶ Replace the combustion air intake pipe.
7.6
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 Combustion Analyser
conforming to BS 7927 and is competent in its use.
NOTICE: Gas inlet pressure
▶ Ensure that the gas inlet pressure has been checked
and is satisfactory, refer to section 6.5.1
Combustion test
When running in maximum output, and the water
temperature is 65°C or less, the boiler will operate both
the central heating and DHW circuits with the diverter
valve in the mid position. It will be necessary to run
sufficient water through the DHW circuit to ensure that
the boiler will not cycle on low heating demands.
This is to allow sufficient time for the setting procedure.
When the water temperature reaches 75°C the diverter
valve will switch to CH only.
▶ Connect the flue gas analyser to the flue gas sampling point (1) as
shown in the figure below.
▶ Ensure that the probe reaches the centre of the flue gas exhaust,
adjust the cone on the probe so that it seals the sample point and
correctly positions the end of the probe.
▶ Press the
and
buttons together
eco
– The chimney sweep symbol will be displayed at the top of the
screen.
– "Max" will flash at the bottom of the screen.
– The boiler will ramp up to maximum output in approximately 30 to
35 seconds.
▶ Run the boiler at maximum output for at least 10 minutes.
▶ Check the CO/CO
readings against the information in table 27.
2
1
Fig. 71 Combustion test
CDi Compact
ErP
- 6 720 813 276 (2015/07)
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