iQe COMFORT 30, Installation And Servicing Instructions

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25
If an electrical fault occurs on the
appliance the preliminary electrical
system checks must be carried out first.
When any service or replacement of
electrical components which has
required the breaking and re-making of
electrical connections has taken place,
the following tests must be repeated:
– earth continuity;
– short circuit;
– polarity;
– resistance to earth.
5.1 EARTH CONTINUITY CHECK
Appliances must be electrically
disconnected, meter set on Ω (ohm)
x 1 scale and adjust zero if necessary.
Tests leads from any appliance earth
point (e.g. inside control box) see wiring
diagrams (section 7) to earth pin on
plug. Resistance should be less than
1 Ω (ohm). If the resistance is greater
than 1 Ω (ohm) check all earth wires for
continuity and all contacts are clean and
tight. If the resistance to earth is still
greater than 1 Ω (ohm) then this should
be investigated futher.
5.2 SHORT CIRCUIT CHECK
Switches turned FULL ON - meter set on
Ω (ohms) x 1 scale. Test leads from L to
N on appliance terminal block, if meter
reads 0 then there is a short circuit.
Meter set on Ω (ohm) x 100 scale. Repeat
it with leads from L to E. If meter reads
less than infinity (
∞
) there is a fault.
NOTE: Should it be found that the fuse
has failed but no fault is indicated,
a detailed continuity check (i.e. by
disconnecting and checking each
component) is required to trace the
faulty component. It is possible that
a fault could occur as a result of local
burning/arcing but no fault could be
found under test. However, a detailed
visual inspection should reveal evidence
of burning around the fault.
5.3 POLARITY CHECK
Appliance reconnected to mains supply
and meter set on 300 V ac scale. Test at
appliance terminal block.
– Test leads from L to N meter reads
approx.: 240 V ac.
– Test leads from L to E “ ” meter
reads approx. 240 V ac.
– Test leads from N to E “ ” meter
reads from 0 to 15 V ac.
5.4 RESISTANCE TO
EARTH CHECK
Appliance must be disconnected from
main supply and meter on Ω (ohm) x 100
scale. All switches including thermostat
on test leads from L to E - if meter reads
other than infinity (
∞
) there is a fault
which should be isolated.
A detailed continuity check is required
to trace the faulty component.
IMPORTANT: These series of checks are
the first electrical checks to be carried
out during a fault finding procedure.
On completion of the service/fault
finding task which has required the
breaking and remaking of electrical
connections then the checks 5.1
Earth continuity, 5.3 Polarity and 5.4
Resistance to earth must be repeated.
5 FAULT FINDING
6.1 REMOVAL OF
BURNER ASSEMBLY
– Isolate from mains
– Remove case cover
– Isolate gas
– Drop down control case
– Remove ignition and ionisation lead
– Disconnect gas pipe from gas valve
to burner mixing arm,
– Disconnect air sensing tube
– Remove air inlet to fan and disconnect
fan wiring
– Remove the four nuts securing the
burner to the heat exchanger
– Carefully remove the burner
assembly
– Check seals and replace if necessary
– Replace in reverse order
– Test for gas tightness
6.2 REMOVAL OF FAN UNIT
– Isolate from mains
– Remove case cover
– Isolate gas supply
– Drop down control cover
– Remove the burner as described in 6.1
– Loosen 2 x 8mm bolts from fan and
remove 2
– Remove fan
– Transfer air hose connector and
restrictor if fitted to now fan
– Refit in reverse order
– Re commission boiler
– Test for gas tightness
6.3 C.H. THERMISTOR
(SM SENSOR)
– Remove case cover
– Unclip thermistor from flow pipe
– Disconnect cable
– Refit in reverse order
6.4 D.H.W. THERMISTOR
(SS SENSOR)
– Remove case cover
– Unclip thermistor from flow pipe
– Disconnect cable
– Refit in reverse order
6.5 SAFETY STAT
– Isolate from mains
– Remove case cover
– Pull clip forwards slide stat upwards
– Remove 2 black wires connected
– Apply heat sink compound to new stat
– Replace in reverse order
6.6 EXHAUST TEMPERATURE
SENSOR
– Isolate from mains
– Remove case cover
– Unplug cable from sensor
– Unscrew sensor
– Refit in reverse order
6.7 IGNITION ELECTRODE
– Turn off power supply
– Remove case cover
– Disconnect electrode from the PCB
– Pull lead through grommet
– Remove electrode fixing screw
– Carefully remove electrode from
burner
– Replace in reverse order.
6.8 IONISATION ELECTRODE
– Turn off power supply
– Remove case cover
6 REPLACEMENT OF PARTS