Setting The Gas/Air Ratio - Worcester GreenStart 25Si Instruction Manual

A
Please note: The flue gas test point can be
accessed on the appliance flue elbow by
removing cap D
D
INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 25Si/30Si
8 716 107 337b (11/05)
33.1
C
Inlet Test Nipple
33.2
33.3
+ –
B
33.4
33.5
–
+
C
SETTING THE GAS / AIR RATIO
THE SETTING OF THE GAS RATIO MUST BE
CARRIED OUT BY A COMPETENT PERSON.
SETTING OF THE GAS RATIO MUST NOT BE
AT T E M P T E D U N L E S S T H E
C A R R Y I N G O U T T H E C O N V E R S I O N I S
EQUIPPED WITH A COMBUSTION ANALYSER
C O N F O R M I N G TO B S 79 2 7
COMPETENT IN ITS USE.
33. Setting the CO
2
Note: When running in the service mode, the
boiler will operate both the central heating &
DHW circuits. This is to allow sufficient time for
the setting procedure. It will be necessary to run
water through the DHW circuit to ensure that
the boiler will not cycle on low heating demands.
33.1 Connect manometer to inlet pressure point
on the gas valve.
To adjust the CO it will be necessary to first
2
operate the boiler at maximum output.
Press and hold down the service button (A) for
10 seconds until illuminated. The blue power
indicator will flash.
33.2 Turn central heating control to maximum;
the boiler will then go to maximum output.
NOTE: The control will resume normal operation
after 15 minutes or if the service button is pressed
for over a second.
33.3 Using a flat blade screwdriver set the CO
via adjuster (B) using table below.
CO settings for Greenstar 25Si and 30Si
2
N . CO should be measured after 10 minutes
OTE
2
Gas type CO setting
2
maximum
Natural gas 9.8%
±0.2
LPG 11.0%
±0.2
Check CO is less than 200ppm.
Measure the inlet pressure; it should be no
less than 18.5mb for natural gas and 37mb
for LPG.
33.4 Set the central heating control to
minimum. This will make the boiler go to
minimum power.
33.5 Measure the CO ; it should now be at the
2
figure for minimum output. If not adjust (C)
on the gas valve until correct.
Return to maximum and re-check the CO
correct press and hold down the service
button for 2 seconds; the button will cease to
be illuminated and the blue power indicator will
be permanently illuminated.
Remove manometer and re-seal inlet pressure
point on gas valve.
Fit new plastic sealing cover on to outlet
adjuster (B).
Fit white cover over valve adjuster (C) and
secure with black security tag.
Remove red arrow from data plate and fit new
one in correct position for gas type.
Re-assemble and refit boiler case.
Re-connect mains electrical supply and
check boiler operation as stated in the
commissioning section.
Fit new label from kit over existing label on the
appliance bottom panel.

SETTING THE GAS/AIR RATIO

P E R S O N
A N D I S
2
CO setting
2
minimum
9.2%
±0.2
10.5%
±0.2
. If
2
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