Fig. 2
Worked example of equivalent flue height
5.1.12 Special consideration must be given to external flues with a view to prevention of condensation and weathering
problems.
5.1.13 An approved terminal should always be used; a ridge terminal or “GC1” terminal is specifically recommended.
The latter should be positioned in a free air space where it is not shielded by any structure. A minimum of 1m
(3ft.) from any vertical or inclined roof structure must be allowed for.
5.1.14 Where flue blocks are used, builders should ensure that no obstruction is created during erection. The installer
should ensure that the connection flue does not project beyond the internal wall of the flue blocks and that there
is provision for examination and servicing.
1.6m
4.6m
H
a
= 6.2m
Ridge Terminal
2 x 300 mm lengths
4 x 1000 mm lengths
45
O
bend
45
O
bend
2 x 300 mm lengths
300 mm length
Flue spigot
100 mm dia flue pipe
6
15
9.
DEFECT DIAGNOSIS
9.1
IMPORTANT: If an electrical defect occurs after installation of the appliance; preliminary earth continuity,
polarity, and resistance to earth checks should be carried out with a multimeter. On completion of any
maintenance/fault-finding task that has required the breaking and remaking of electrical connections, then
checks of continuity, polarity, and resistance to earth must be repeated.
9.2
WARNING:
When purging or checking gas supplies, ensure that the ventilation to the room or cupboard is adequate, and
that all naked lights are extinguished.
SYMPTOM
POSSIBLE CAUSE
REMEDY
a.
Pilot will not light.
i.
No gas supply to heater.
Check for gas at inlet pressure test
point on Multifunctional Control.
ii. Gas supply pipe not purged.
Purge gas supply pipe in accordance
with BS 6891.
iii Pilot orifice restricted.
Clear pilot orifice or replace pilot injector.
iv. Piezo system faulty.
Check igniter, lead, and electrode.
v. Excessive gas supply pressure.
Check that mains gas pressure is 37mbar,
and reduce if necessary.
b.
Pilot lights but goes
i.
Connection between thermo-
Check connection is secure.
out on releasing START
couple and Multifunctional
button during initial
Control not secure.
light-up, or after
normal operation.
ii. Faulty Multifunctional
Replace Multifunctional Control.
Control.
iii. Faulty Thermocouple.
Replace Thermocouple.
c.
Main burner opera-
i.
Gas rate or burner pressure
Check gas rate and burner pressure
ting intermittently
setting high.
setting.
with fan running.
ii. Temperature rise excessive.
Adjust fan speed or gas rate accordingly.
iii. Air filter or return air path
Check filter is clean and air path is clear.
restricted.
iv. Excessive number of outlets
Open additional outlets.
closed.
v. Spillage of flue gases.
Carry out spillage test and rectify.
vi. Spillage monitor device (TTB)
Replace Spillage device (TTB)
faulty.
d.
Pilot alight but main
i.
Mains electrical supply not
Check mains supply.
burner not igniting.
connected to heater.
ii. Controls not demanding heat
Check that time control and
room thermostat are operating correctly.
iii. T3.15A fuse failed.
Replace. If failure occurs again, check
wiring for short circuits.
iv. Loose connection to room thermo-
Check connections.
stat, Limit Switch, gas control lead,
time control, or transformer.
v. 230V/24V transformer failure.
Check 24V side with test meter, if voltage
missing, replace transformer.
vi. Faulty relay module
Check 230V at white wire from switch S5
vii. Multifunctional Control faulty.
Replace Multifunctional Control.
viii.Limit Switch faulty.
Short circuit control and replace Fan Delay/
Limit control if necessary.
ix. Room thermostat or external
Fit temporary loop in heater thermostat
wiring faulty.
socket. If heater ignites, external circuit
or room thermostat is faulty.
x. Spillage device faulty
Check Spillage device and wiring for open
circuit.
