Combustion Analysis Test; Checking The Expansion Vessel; External Faults; Electrical Checks - Benchmark UNICA HE Series Installation & Servicing Instructions Manual

Compensation
pipe connection
fig. 37
7.4.2 GAS VALVE MINIMUM SETTING
Locate and gently turn the HTG trimmer till the
minimum value fan speed (max) is obtained and
check that it corresponds with the appropriate CO
value (Minimum) for the respective appliance. If
the CO reading is correct, rotate the HTG trimmer
2
until the correct value is obtained for the respective
appliance (see fan speed table) and proceed to
7.4.3.
However, If the CO
minimum gas pressure must be adjusted as
follows:
• Using a suitable screwdriver, very slowly turn the
minimum adjustment screw (see fig. 38) –
clockwise to increase, counter clockwise to
decrease - until the correct value is displayed on
the CO analyser (allow time for the analyser to
2
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. Refit the 3-selector knobs
and move the mode selector to the OFF position.
Remove the test probe from the test point and refit
the sealing screw/s and/or cap.
IMPORTANT
A GAS SOUNDNESS 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).
• Insert the flue gas analyser probe into the flue
gas test point (see fig. 35).
• Operate the boiler in CO mode 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

CHECKING THE EXPANSION VESSEL

Carry out the component removal procedure as
described in 6.4. You must ensure that the boiler
is completely drained of water. Using a suitable
pressure gauge, remove dust cap on expansion
vessel and check the charge pressure. The
correct charge pressure should be 1.0 bar ± 0.1
bar. If the charge pressure is less, use a suitable
pump to increase the charge.
NOTE
You must ensure the drain valve is in the open
position whilst re-charging takes place. Replace
the dust cap and carry out the relevant
commissioning procedure (section 5).
7.7

EXTERNAL FAULTS

Before carrying out any faultfinding or component
replacement, ensure the fault is not attributable to
any aspect of the installation.
Maximum
screw
Minimum
screw
reading is incorrect, the
2
7.7.1 INSTALLATION FAULTS
Symptom
No display/ignition
No hot water
No heating
Fault code
10
7.8

ELECTRICAL CHECKS

Any electrical checks must be carried out by a
suitably qualified person.
2
7.8.1 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.
7.8.2 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 (fig.17). Repeat
above test on the Live & Earth connections at the
appliance terminal strip (fig.16)
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.
7.8.3 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
connections at the appliance terminal strip (fig.16).
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
connections at the appliance terminal strip (fig.16).
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 (fig.16).
The meter should read approximately 0 – 15Vac.
If so polarity is correct. If not, see 7.8.4.
7.8.4 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.
7.8.5 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 (fig. 16). If the meter reads other than infinity
there is a fault that must be isolated, carry out a
detailed continuity check to identify the location of
the fault.
Possible cause
Check wiring/check electrical
supply
Check pipe-work
Check external controls
Possible cause
Check gas supply, check flue
system, check polarity
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