0108MLOOGBEN
17
SECTION 11 FAULT FINDING
11.1 Air heater will not light :
A) Read lighting instructions;
B) Check gas supply is turned on;
C) Check electricity supply is switched on;
D) Check burner control lockout condition: Fig.10
Key 9 local or remote. Reset as applicable
E) Check thermal overheat control lockout condition:
Fig.10 Key 7. Reset local
F)Combustion air fan not rotating: check free to run
G) Combustion air fan running air flow not being
sensed:
Check connections to reference ports on heater
and pressure switch - check connection tubes not
perforated - check no condensation in tubes -
check flue is not blocked - check combustion air
inlet duct is not blocked - check flue length &
combustion air duct length Re. section 4 - check
operation of pressure switch by: disconnecting
tube and gently blowing into tube, switch should
be heard to click or metered to indicate switch
opening/ closing
N.B. Terminals 1 & 2 normally closed position no air
flow.
Terminals 1 & 3 normally open and close on positive
air flow 6.5 - 7.5 mbar.
Faulty pressure switch! renew.
H) Faulty burner control! renew.
J)Faulty ignition device or wire connection: check
earth potential/continuity, Faulty! Renew
K) Faulty gas valve : renew.
11.2 Heater tries to light igniter glows brightly
Gas turned off ?
Air in gas supply - check purged supply.
Gas pressure inlet too low/high - check, if necessary
call gas supplier.
Gas valve not operating: check wiring - check valve
- check burner control renew as appropriate.
11.3 Burner lights & goes out immediately :
Insufficient flame proving current: check ignition
device & wiring measure flame current 7.6: faulty
burner control - flame sensor electrode incorrectly
located!
11.4 Cool air during operation - continuously when burner
is off:
A) Ensure specification is not for constant run fan
(CRF);
B) Low gas pressure - check, adjust if not in
accordance with data plate;
C) Manual fan override switch if fitted set to on -
check and switch off;
11.5 Air circulation fan will not run:
A) Open circuit - check wiring;
B) Faulty thermal fan control switch - check renew;
C) Defective capacitor - check renew;
D) Defective motor - check renew;
E) Fan blocked - check it rotates freely.
11.6 Air circulation fan runs and stops while gas burner
remains alight:
A) Thermal fan control switch faulty or incorrectly
wired - check circuit against wiring diagram;
B) Faulty fan control switch - renew;
C) Faulty fan motor - renew;
D) Low ambient air temperature causing fan control
switch to cool and open circuit - maintain higher
ambient temperature near the air heater. This
symptom will cease as the heating period
lengthens due to gradual rise of air-on
temperature.
11.7 Air circulation fan cycling on its thermal overload
protector:
- Check electrical current rating - check power supply
- check fan rotates freely and is not imposing an
abnormal load - check capacitor is operational.
11.8 Air heater cycles on thermal overheat control LC1:
A) Control faulty - renew;
B) Air flow restricted - clean fan assembly; check
louvre setting;
C) Fan faulty - renew;
D) Gas rate too high - adjust burner gas pressure;
E) Local ambient air temperature near the air heater
too high - above 30° check for stratification -
install a Reznor "Maximizor" and save energy!
11.9 Air circulatory fan keeps running :
Faulty fan control : renew.
Gas valves open : check valve or wiring fault by
removing wires at valve solenoid terminals by
unplugging.
Faulty valve : renew.
Faulty wiring : correct.
End of fault finding guide.
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