Bosch CONDENS 5000W - Flue Gas Analysis

Servicing and spares
Bosch Condens 5000W – 6 720 646 195 (2018/10)
38
▶ After measurement replace test point cover.
▶ The pressure will read negative, refer to the chart in figure 68.
Fig. 68 Fan pressure readings
If the boiler fails the fan pressure test then before adjusting the air/gas
ratio, try the following:
▶ Check the syphon is not blocked.
1. Remove the screws securing the sump cover.
2. Remove the sump cover.
3. Clean the sump and heat exchanger with a suitable brush
Fig. 69 Sump access
▶ Check the exhaust path and flue for restriction.
▶ Clean the heat exchanger with a suitable cleaning tool. refer to
section 6.7 "Checking the heat exchanger".
▶ Re-check the fan pressure readings
6.5 Flue gas analysis
Combustion test:
▶ Connect the flue gas analyser to the flue gas sampling point as shown
in the figure 70.
▶ Run the boiler at maximum output for at least 10 minutes.
▶ Check the CO/CO
2
readings against the information in table 18 CO/
CO
2
settings.
Fig. 70 Combustion test
[1] Air inlet sample point
[2] Flue gas sample point
If the boiler fails the combustion test, check:
▶ Air intake for restriction.
▶ Diaphragm in the fan, for correct operation.
▶ Cleanliness of the heat cell, plus blockages in the condensate
disposal.
NG Boiler
FAN PRESSURE TEST
Clean Heat Ex.
Heat Ex. ok
LPG Boiler
ZSB18-2A-23:
- 0.8
0
-0.6
-0.5
-0.4
-0.3
-0.2-0.1
-0.8
-0.7
kPa
ZSB18-2A-31:
- 0.74
0
-0.6
-0.5
-0.4
-0.3
-0.2-0.1
-0.8
-0.7
kPa
6720646195-13.1Wo
1.
1.
6720644743-24.1Wo
2.
3.
6720646195-12.1Wo
1
2