FAULT FINDING
Fault Possible Cause Remedy
1. Combustion air fan does not start a) No air pressure in duct (positive or negative) a) Switch on main duct fan
b) Combustion air switch set too low b) Reset switch
c) Duct air switch set too high c) Reset Switch
d) If low gas pressure switch fitted, gas pressure too
low or switch set too high
d) Adjust gas pressure or reset switch
e) If high gas pressure switch fitted, gas pressure
too high or switch set too low
e) Decrease gas pressure or reset switch
2. Combustion air fan starts, but burner goes to
Lockout
a) Combustion air switch set too high a) Reset switch
b) Incorrect fan rotation b) Correct
c) Fan blades dirty c) Clean fan
3. No spark. Burner goes to lockout.
a) High tension lead not properly tightened at
terminations
a) Tighten lead ends
b) Spark plugs not properly adjusted b) Adjust as necessary
c) Transformer failed c) Change transformer
4. Pilot does not light a) No gas a) Find cause and rectify
b) Too much gas b) Adjust gas pilot cock
c) Pilot valve not opened c) Change valve or find open circuit
5. Pilot lights but burner goes to ‘lockout’ Flame not detected because:
a) UV cell not looking at flame a) Re-align cell
b) UV cell faulty b) Check output. Change cell
c) Flame probe not in flame c) Rectify
d) Bad earth d) Check output of probe. Make good earth
connection
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