SETTING THE AIR/GAS RATIO
SER
VICING
& SP
ARES
INSTALLATION & SERVICING INSTRUCTIONS
46
SETTING THE GAS/AIR RATIO
8 716 115 219b (09.2008)
GAS TYPE
CO
2
setting
maximum.
Natural Gas
Type H (G20)
LPG (propane)
(G31)
9.4 ±0.5%
8.6 ±0.5%
10.8 ±0.5%
10.4 ±0.5%
E
A
B
D
C
1
2
3
4
5
C
Greenstar Highflow 440CDi
CO
2
setting
minimum.
GAS TYPE
CO
2
setting
maximum.
Natural Gas
Type H (G20)
LPG (propane)
(G31)
9.4 ±0.5%
9.0 ±0.5%
10.8 ±0.5%
10.4 ±0.5%
Greenstar Highflow 550CDi
CO
2
setting
minimum.
IMPORTANT: The appliance is set at the
factory and adjustment to the CO
2
settings (air/gas ratio) is only required
where the appliance has been stripped
down and assembled or if the fan, burner
or gas valve are replaced or the appliance
has been converted to a different gas
type.
The air/gas ratio may only be adjusted on
the basis of a CO
2
measurement at
maximum and minimum heat output using
an electronic tester.
Setting the gas ratio MUST ONLY be
carried out by a competent person
equipped with a combustion analyser
conforming to BS 7927 and competent in
its use.
1
Connect manometer to the inlet pressure
point (A) on the gas valve.
2 To adjust the CO
2
it will be necessary to
first operate the boiler at maximum output.
Press and hold down the boost button
(B) for 10 seconds.
Turn temperature control (C) to
maximum, the boiler will then go to
maximum output.
Note: the control will resume normal
operation after 15 minutes or if the boost
button (B) is pressed for more than 1 second.
3
Remove plastic cap and using a flat
bladed screwdriver, set the CO
2
via adjuster
(D) referring the table opposite.
Note: CO
2
should be measured 10 minutes
after firing the boiler.
Check the CO is less than 200ppm.
Measure the inlet pressure, it should be
between 17 - 19mbar (nominally 18 mbar)
for Natural Gas and between 35 - 39mbar
(nominally 37mbar) for LPG.
4
Turn the temperature control (C) to
minimum. This will make the boiler go to
minimum output.
5
Measure the CO
2
it should now be at the
figure for minimum output shown on the
table opposite. If not, remove cap and
adjust (E) on the gas valve until correct.
Check the CO is less than 200ppm.
Turn temperature control to maximum
output and recheck the CO
2
. If correct,
hold down the boost button (B) for two
seconds, the boiler should return to normal
operating mode with the blue power
indicator permanently illuminated.
Remove manometer and re-seal the inlet
pressure point on the gas valve.
Fit a new plastic sealing cover to outlet
adjuster (D) and replace the cap on the
gas valve.
Remove red arrow from data plate and
fit a new one in the correct position for
gas type.
