Setting The Air/Gas Ratio - Worcester GREENSTAR 12i Instruction Manual

THIS PAGE SHOWS THE SETTING PROCEDURE FOR THE SIT VALVE
FOR ALTERNATIVE VALVES SEE PAGE 54 FOR DUNGS VALVE.
A
D
WHEN RUNNING IN SERVICE MODE
NOTE: When fitted with the optional
diverter valve (not supplied) and
running in service mode, the boiler
will operate both central heating and
hot water circuits.
If fitted to an S or Y plan system, the
system must only be run in central
heating mode.
INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 12i/24i System
8 716 115 167b (03/2009)
Max
'B'
Min
'C'
Inlet Test Nipple
Max
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
26.1
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.
26. Setting the CO/CO
Note: When running in the service mode, when an
integral diverter valve is fitted, 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.
26.1 Connect manometer to inlet pressure point
on the gas valve.
26.2
To adjust the CO/CO
first operate the boiler at maximum output.
26.3
Press and hold down the service button (A) for
10 seconds until illuminated. The blue power
indicator will flash.
26.2 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.
26.3 Using a 2.5mm allen key set the max
CO/CO via adjuster (B) using the table
2
below.
'B'
CO/CO settings for Greenstar i System
2
N . CO/CO
OTE
after 10 minutes
Gas type CO
Natural gas 9.8% ± 0.5%
LPG 11.0% ± 0.5%
CO - less than 200ppm (0.002 ratio)
26.4
Check CO is less than 200ppm.
Measure the inlet pressure; it should be
no less than 18.5mb NG or 37mb for LPG.
26.4 Set the central heating control to
minimum. The boiler will go to minimum
power.
26.5 Measure the CO/CO
26.5 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
adjust CO . Replace dust cap.
2
Check that the CO is less than 200ppm.
Return to maximum and re-check the CO/CO
If 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.
Re-assemble and refit boiler case.
Min
'C'
REPLACEMENT OF PARTS
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
should be measured
2
setting CO setting
2 2
maximum minimum
9.2% ± 0.5%
10.5% ± 0.5%
and check against the
2
.
2
53