To Clean The Condensate Trap; Setting The Air/Gas Ratio - Worcester 29CDi Classic Installation, Commissioning And Servicing Instructions

SERVICING AND SPARES
6.1.7

TO CLEAN THE CONDENSATE TRAP

1. Pull condensate hose out of the trap.
2. Remove trap from boiler.
▶ Clean trap and check that the heat exchanger connection is clear.
▶ Fill the condensate trap with approximately 1/4 litre of water and
refit in reverse order.
2.
1.
Fig. 70 Siphon removal
6.2

SETTING THE AIR/GAS RATIO

NOTICE: Air/Gas ratio
▶ The setting of the gas ratio must be carried out by a
competent person.
Setting the air/gas ratio must not be attempted
unless the person carrying out the operation is
equipped with a combustion analyser conforming to
BS 7927 and is competent in its use.
SETTING THE CO
2
When running in the Performance test mode, the boiler
will operate only the central heating circuit.
To avoid the boiler cycling on low heating demands,
remove the diverter valve motor from the valve body and
run the domestic hot water tap throughout the
Performance test mode.
Refit the diverter valve motor once all the tests are
completed,  page 47
1. Connect manometer to inlet test point on the gas valve.
▶ To adjust the CO it will be necessary to first operate the boiler at
2
maximum output.
▶ Press and hold down the Performance test mode button for 10
seconds until illuminated.
2. Turn central heating control to maximum; the boiler will then go to
maximum output.
The control will resume normal operation after 15
minutes or if the Performance test mode button is
pressed for over a second.
3. Using a flat blade screwdriver set the CO
referring to the table below.
CO should be measured 10 minutes after firing the
2
appliance.
42
6 720 815 725-13.1O
via the max adjuster
2
Gas type CO setting maximum CO
2
ErP
Greenstar 29CDi Classic and 34CDi Classic
Natural gas 9.6% ±0.4
LPG 11.5% ±0.4
ErP
Greenstar 38CDi Classic and 42CDi Classic
Natural gas 9.7% ±0.4
LPG 11.5% ±0.4
NOTE:
When checking an existing appliance the tolerance is 0.4%.
If checking after cleaning or component replacement or for adjustment
when the reading is outside the tolerance given above, then the
tolerance is 0.2%
CO - less than 200 ppm (0.002 ratio)
Table 13
▶ Check CO is less than 200 ppm.
▶ Measure the gas inlet pressure at the gas valve test point; it should be
no more than 2.5mbar less than the pressure at the meter for natural
gas and no more than 4mbar less than the pressure at the regulator
for LPG.
4. Set the central heating control to minimum. This will make the boiler
go to minimum power.
5. Measure the CO ; it should now be at the figure for minimum output.
2
▶ If not, use a 4mm Allen key to adjust the min adjustment on the gas
valve until correct.
▶ Return to maximum and re-check the CO
▶ If correct press and hold down the Performance test mode button for
two seconds; the button will cease to be illuminated.
▶ Remove manometer and re-seal inlet pressure point on gas valve.
▶ Fit new plastic sealing cover onto the max adjuster.
▶ Replace the brass screw over the min adjuster on the valve.
▶ Re-assemble and refit boiler case.
Max
adjust
Min
adjust
4mm
Inlet pressure
test point
Fig. 71 Setting the Air/Gas ratio
setting minimum
2
ErP
9.0% ±0.4
10.5% ±0.4
ErP
9.1% ±0.4
10.5% ±0.4
.
2
6720647361-48.1Wo
6 720 815 725 (2015/05)