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

THIS PAGE SHOWS THE SETTING PROCEDURE FOR THE SIT VALVE
FOR ALTERNATIVE VALVE SEE PAGE 55 DUNGS.
A
Please note: The flue gas test point can be
accessed on the appliance flue elbow by
removing cap D
D
54
REPLACEMENT OF PARTS
Max
'B'
Min
'C'
Inlet Test Nipple
Max
INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 25Si/30Si
SETTING THE AIR / GAS RATIO
FOR THE SIT 848.093 SIGMA
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
30.1
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
COMPETENT IN ITS USE.
30. Setting the CO/CO
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
sufficient water through the DHW circuit to
ensure that the boiler will not cycle on low
heating demands.
30.1 Connect manometer to inlet pressure point
on the gas valve.
To adjust the CO/CO
30.2
first 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.
30.2 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.
30.3
30.3 Using a 2.5mm allen key set the CO/CO
via adjuster (B) using the table below.
'B'
CO/CO
2
N . CO/CO
OTE
Gas type
Natural gas
LPG
CO - less than 200ppm (0.002 ratio)
Check CO is less than 200ppm.
30.4
Measure the inlet pressure; it should be no
less than 18.5mb NG or 37mb for LPG.
30.4 Set the central heating control to minimum.
The boiler will go to minimum power.
30.5 Measure the CO/CO
table above. If required adjust (C) on the gas
valve until the correct measurement is set.
Remove brass dust cap with flat bladed
screw driver. Then using a 4mm allen key
30.5
adjust CO
Check that the CO is less than 200ppm.
Return to maximum and re-check the
CO/CO . If correct press and hold down the
2
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.
Re-assemble and refit boiler case.
Min
'C'
8 716 115 165a (06/2008)
U N L E S S T H E P E R S O N
TO B S 79 2 7 A N D I S
2
it will be necessary to
2
2
settings for Greenstar Si
should be measured
2
after 10 minutes
CO setting CO setting
2 2
maximum minimum
9.8% ± 0.5%
9.2% ± 0.5%
11.0% ± 0.5% 10.5% ± 0.5%
and check against the
2
. Replace dust cap.
2