26
pressure must be adjusted as follows:
Using a 2,5mm Allen key, very slowly turn the minimum
adjustment screw (see fi g. 36) – clockwise to increase,
counter clockwise to decrease - until the correct value
is displayed on the CO
2
analyser (allow time for the
analyser to stabilise).
7.4.3 COMPLETION
On completion of the combustion analysis check and/or
any gas valve adjustment, set the HTG trimmer to the
corresponding value as detailed in the fan speed table.
Move the mode selector to the OFF position. Remove
the test probe from the test point and refi t the sealing
screw/s and/or cap.
Refi t the cap on PCB cover, the knobs, the control panel
with screws and refi t the appliance casing as detailed
in 4.7.
IMPORTANT
A GAS TIGHTNESS CHECK MUST BE CARRIED OUT
IF ANY GAS CARRYING COMPONENTS HAVE BEEN
REMOVED, REPLACED, OR DISTURBED .
7.5 COMBUSTION ANALYSIS TEST
A combustion analysis check can easily be carried out
on the appliance via the test points located on the top of
the appliance (see 7.4).
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’.
Use the CO
2
values for ‘casing-on’ when you are car-
rying out a combustion analysis check.
Insert the fl ue gas analyser probe into the fl ue gas test
point (see fi g. 37).
Operate the boiler at full output and compare the values
with those shown in section 2 (Nat. Gas) or section 10
(LPG). If different adjust the gas valve according to
7.4.1, 7.4.2, & 7.4.3.
7.6 EXTERNAL FAULTS
Before carrying out any faultfi nding or component replace-
ment, ensure the fault is not attributable to any aspect
of the installation.
7.6.1 INSTALLATION FAULTS
7.7 ELECTRICAL CHECKS
Any electrical checks must be carried out by a suitably
qualifi ed person.
7.7.1 EARTH CONTINUITY TEST
Isolate the appliance from the electrical supply, and using
a suitable multi-meter carry out a resistance test. Connect
test leads between an appliance earth point and the earth
wire of the appliance supply cable. The resistance should
be less than 1 OHM. If the resistance is greater than 1
OHM check all earth wires and connectors for continuity
and integrity.
7.7.2 SHORT CIRCUIT CHECK
Isolate the appliance from the electrical supply, and
using a suitable multi-meter, carry out a short circuit test
between the Live & Neutral connections at the appliance
terminal strip (fi g.21). Repeat above test on the Live &
Earth connections at the appliance terminal strip (fi g.21).
NOTE
Should it be found that the fuse has failed but no fault is
indicated, a detailed continuity check will be required to
trace the fault. A visual inspection of components may
also assist in locating the fault.
7.7.3 POLARITY CHECK
With the appliance connected to the electrical supply
and using a suitable multimeter, carry out the following
voltage tests:
●
Connect test leads between the Live & Neutral connec-
tions at the appliance terminal strip (fi g. 21). The meter
should read approximately 230V ac. If so proceed to
next stage. If not, see 7.8.4.
●
Connect test leads between the Live & Earth connec-
tions at the appliance terminal strip (fi g.21). The meter
should read approximately 230V ac. If so proceed to
next stage. If not, see 7.8.4.
●
Connect test leads between the Neutral & Earth
connections at the appliance terminal strip (fi g.21).
The meter should read approximately 0 – 15Vac. If so
polarity is correct. If not, see 7.8.4.
7.7.4 REVERSED POLARITY OR SUPPLY FAULT
Repeat the above tests at the appliance isolator, if testing
reveals correct polarity and/or supply at the isolator, re-
check wiring and connections between the isolator and
the appliance. If tests on the isolator also reveal reversed
polarity or a supply fault, consult the local electricity
supplier for advice.
7.7.5 RESISTANCE TO EARTH CHECK
Isolate the appliance from the electrical supply, and using
a suitable multi-meter carry out a resistance test. Connect
test leads between the Live & Earth connections at the
appliance terminal strip (fi g. 21). If the meter reads other
than infi nity there is a fault that must be isolated, carry
out a detailed continuity check to identify the location of
the fault.
These series of checks must be carried out before at-
tempting any faultfi nding procedures on the appliance.
On completion of any task that required the disconnection
and re-connection of any electrical wiring or component,
these checks must be repeated.
7.8 FAULT FINDING
Before attempting any faultfi nding, the electrical checks
as detailed in 7.8 must be carried out. Isolate the applian-
ce from the electrical supply.
Disconnect any external controls from terminal plug M5
(fi g. 16), and insert a link-wire between the two wires at
the ‘TA’ connections (fi g. 21).
Symptom
Possible
cause
No display/ignition
Check wiring/check
electrical
supply
No hot water
Check external controls
No heating
Check external controls
Fault code
Possible cause
10
Check gas supply, check
fl ue system, check polarity
CASING OFF CASING ON
CO
2
8.8%
9.0%
Fig. 37
Internal fl ue
gas analysis
test point
External fl ue gas
analysis test point
