31
Use the CO
2
values for ‘casing-off’ when you are
making adjustments to the gas valve.
10.6.1 GAS VALVE MAXIMUM SETTING
Lower the controls fascia and remove the cap
(A)
on the
PCB cover (fi g. 44).
Locate and gently turn the HTG trimmer till the maximum
value (fan speed) is obtained and check that it corre-
sponds with the appropriate CO
2
value (Maximum) for
the respective appliance. If the CO
2
reading is correct,
proceed to gas valve minimum setting (7.4.2).
However, if the CO
2
reading is incorrect, the maximum
gas pressure must be adjusted as follows:
Using a suitable screwdriver, very slowly turn the
maximum adjustment screw (see fi g. 45) – clockwise
to decrease, counter clockwise to increase – until the
correct value is displayed on the CO
2
analyser (allow
time for the analyser to stabilise).
SECTION 10 LPG INSTRUCTIONS
10.3 CONVERTING THE APPLIANCE GAS TYPE
To convert the appliance to another gas type it is necessary
to change the burner injector and adjust the gas valve.
To change the injector see 6.12.1.
To adjust CO
2
value see 7.4.1-2-3.
10.4 GAS SUPPLY
The gas supply must be connected to the appliance by a
competent LPG installer and must be of suffi cient size to
supply the appliance at its maximum output. An existing
supply must be checked to ensure that it is of adequate
size to deal with the maximum rated input of this and any
other appliances that it serves.
10.5 GAS SUPPLY INSTALLATION
The entire installation including the meter must be purged
and checked for gas soundness.
10.6 CORRECTING THE CO2 VALUES/ADJUSTING
THE GAS VALVE
THE GAS VALVE MUST BE SET-UP OR ADJUSTED
WITH THE AID OF A PROPERLY CALIBRATED FLUE
GAS ANALYSER.
NOTE
To adjust the gas valve you must fi rst ensure that the
fan speed potentiometers (trimmers) have been set
correctly (see 7.3).
Isolate the appliance from the electrical supply and remove
the appliance casing as described in 4.7.1. Set the fl ue
gas analyser to read CO
2
and insert the probe into the
fl ue analysis test point (fi g. 37). Restore the electrical sup-
ply to the boiler and switch the boiler to the OFF mode.
Remove the PCB cover and the two selector knobs. .
Locate/identify the CO button (see fi g. 34). Press the
CO button; the appliance will now operate in CO mode
for approximately 15-minutes (see 7.9).
IMPORTANT
There are 2-sets of CO
2
values for the appliance,
i.e. a value for the casing ‘on’ and a value for the
casing ‘off’.
10.1 RELATED DOCUMENTS
BS 6798
BS 5449
BS 5446
BS 5440
BS 5482
PART 1
PART 1
PART 1
INSTALLATION OF BOILERS OF RATED INPUT NOT EXCEEDING 60 kW
FORCED CIRCULATION HOT WATER SYSTEMS
INSTALLATION OF GAS HOT WATER SUPPLIES FOR DOMESTIC PURPOSES
FLUES
DOMESTIC BUTANE & PROPANE GAS BURNERS IN PERMAMENT DWELLINGS
10.2 TECHNICAL DATA
Gas Pressures
15VHE
Inlet pressure
37.00
Maximum gas rate
1.16
kg/hr
Minimum gas rate
0.27
kg/hr
Injector
size
3.6
mm
Effi ciency
SEDBUK
(%)
92.5
Band
“A”
Emissions
CO max (p.p.m.)
200
p.p.m.
CO min (p.p.m.)
15
p.p.m.
NOx max (p.p.m.)
30
p.p.m.
NOx min p.p.m.)
20
p.p.m.
CO
2
max
10.0
%
CO
2
min
10.0
%
CO/CO
2
ratio (max)
0.002 to 1
CO/CO
2
ratio (min)
0.0005 to 1
CASING OFF CASING ON
CO
2
9.8%
10.0%
Fig. 42