
FA
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INSTALLATION & SERVICING INSTRUCTIONS
46
CENTRAL HEATING FUNCTION
6-720-611-730b (12.05)
NOTE: The sequence ensures that the condensate
siphon is not empty after long OFF periods.
CENTRAL HEATING FUNCTION
MAIN SWITCH
ON
GREEN LIGHT
ON
CENTRAL
HEATING
DEMAND
Fan to start speed.
Gas valve open.
Ignition spark 5
second max.
BURNER LIT?
RED LIGHT ON
Burner stabilises
at start speed for
5 - 10 seconds.
Fan reduces over
15 seconds.
Fan min. speed for
90 seconds.
Boiler unused for
long period?
Boiler operates to
match system load
and CH control
setting.
CH demand
satisfied.
Gas valve closes.
Red light OFF.
Pump and fan run
for up to 3 mins.
YES
NO
Fan run to purge
gas from burner.
5th Attempt?
NO
LOCKOUT
YES
Burner remains
OFF until flow
temperature is
below set value.
Pump ON.
Diverter valve to
CH position.
Gas valve shuts.
Pump remains
ON.
Over temperature
shut-down if water
temperature is 5°C
above set value.
YES
NO
Minimum heat
input for 15 min.