Instruction manual

SETTING THE AIR / GAS RATIO
FOR DUNGS GB-ND 055 DO1 S20
THE SETTING OF THE GAS RATIO MUST BE
CARRIED OUT BY A COMPETENT PERSON.
SETTING OF THE GAS RATIO MUST NOT BE
ATTEMPTED UNLESS THE PERSON
CARRYING OUT THE CONVERSION IS
EQUIPPED WITH A COMBUSTION ANALYSER
CONFORMING TO BS 7927 AND IS
COMPETENT IN ITS USE.
THIS PAGE SHOWS THE SETTING PROCEDURE FOR THE DUNGS
VALVE FOR ALTERNATIVE VALVES SEE PAGE 53 FOR SIT VALVE.
26. Setting the CO/CO
2
Note: When running in 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.
 To adjust the CO/CO
2
it will be necessary to
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.
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 2mm hexagonal ball driver set the
max CO
2
via adjuster (B) using table below.
 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
2
and check against the
table above. If required adjust (C) on the gas
valve, using a 2mm hexagonal ball driver,
until the correct measurement is set.
 Check that the CO is less than 200ppm.
 Return to maximum and re-check the
CO/CO
2
. 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.
26.1
26.3
26.5
26.4
Inlet Test Nipple
+
I
C
B
C
+
I
26.2
A
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.
D
Gas type
CO/CO
2
settings for Greenstar i System
NOTE. CO/CO
2
should be measured
after 10 minutes
Natural gas
LPG
9.8% ± 0.5%
11.0% ± 0.5%
9.2% ± 0.5%
10.5% ± 0.5%
CO
2
setting
maximum
CO
2
setting
minimum
CO - less than 200ppm (0.002 ratio)
REPLACEMENT OF PARTS
INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 12i/24i System
8 716 115 167b (03/2009)
54
SERVICING
& SPARES