Servicing and spares
39
Bosch Condens 5000W – 6 720 646 195 (2018/10)
6.6 Setting the air/gas ratio
NOTICE:
Combustion testing
▶ Setting of the gas ratio must be carried out by an authorised person.
Setting of the gas ratio must not be attempted unless the person
carrying out the test is equipped with a calibrated combustion
analyser and is competent in it‘s use.
6.6.1 Setting the CO/CO
2
When running in the service mode, the boiler will operate the central
heating. This is to allow sufficient time for the setting procedure.
▶ Refer to section 6.2 "Check the gas inlet pressure" and ensure that
the gas inlet pressure is correct before continuing.
▶ To adjust the CO/CO
2
it will be necessary to first operate the boiler at
maximum output.
1. Press and hold down the service button for more than 10 seconds
until illuminated (refer to figure 71).
– The blue power indicator will pulse 5 times.
2. Turn central heating control to maximum (refer to figure 71).
– The boiler will then go to maximum output.
▶ Refer to table 18 and check the CO/CO
2
at maximum and if required
adjust for maximum via adjuster [1] figure 72 using a 2.5mm Allen
key.
▶ Check CO is less than 200ppm for Natural Gas and less than 250ppm
for LPG.
3. Set the central heating control to minimum (refer to figure 71).
– The boiler will go to minimum output.
▶ Measure the CO/CO
2
and check against table 18.
If required set the minimum CO/CO
2
via adjuster [2] figure 72 on the
gas valve until the correct measurement is set:
– Remove dust cap with flat bladed screw driver.
– Using a 4mm Allen key adjust CO
2
.
– Replace the dust cap.
Fig. 71 Setting the boiler to minimum or maximum
▶ Check that the CO is less than 200ppm for Natural Gas and less than
250ppm for LPG.
▶ Return to maximum and re-check the CO/CO
2
.
If correct, press the service button;
the button will cease to be illuminated and the blue power indicator
will be permanently illuminated.
▶ Re-assemble and refit boiler case.
Fig. 72 Gas valve adjustment
CO/CO2 settings for Condens 5000W
Table 18 CO/CO
2
settings
1.
2.
3.
6720643895-120.1Wo
CO/CO
2
should be measured after 10 minutes
Gas type CO
2
maximum CO
2
minimum
Natural Gas 9.8% ± 0.5 9.2% ± 0.5
LPG (Propane)
Set by manufacturer
10.8% ± 0.2 10.2% ± 0.2
NOTES:
▶ Appliances intended for use with LP gas (Propane or Universal)
must intially be set on propane at 10.8% (max.) and 10.2% (min.)
and at these CO
2
settings the appliance will operate satisfactorily
on Unviversal LP gas.
The exhaust of an appliance operating on Universal LP gas will
however indicate a CO
2
concentration of up to 12.8% but will need
no adjustment.
▶ When checking an existing boiler the tolerance is ± 0.5.
▶ If checking after cleaning or component replacement or for
adjustment when the reading obtained is outside the tolerances
given above, then the tolerance is ± 0.2.
CO - less than 200 ppm (0.002 ratio) Natural Gas.
CO - less than 250 ppm (0.0025 ratio) LPG.
6720643895-66.1Wo
2
1
MAX
MIN
2.5 mm
4 mm
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