FIND FAULT
POSSIBLE CAUSES SOLUTION
Main flame does not
light and burner locks
out at the end of the
pilot phase
Faulty main shut off valve
Check electrical supply to
valve
Check condition of the valve,
if faulty, replaces
No main gas
Check manual valve open
Check the adjustment of the
gas control valve
Ensure gas is available at
burner
Not enough main gas
Check main gas flow adjuster
and main gas regulator
Main flame lights but
shuts down after a short
period of time
Pilot gas rate too high
Adjust pilot gas rate
Control circuit operating
Check control circuit, over
temperature
limits etc.
Burner gas or air ports
blocked
Check and Clean
Identify source of blockage
and rectify
Flame sensor not detecting
the
flame
Over firing and flame is
‘lifting off’ reset main flame
firing rate
Check flame sensor
installation and position
Check the main gas pressure
governor
Fault Finding Guide
Comtherm Ltd
Installation & Maintenance Manual
Page 12
Burners, Heaters & Combustions Systems