FAULT FINDING & DIAGNOSIS
6 720 815 725 (2015/05)
56
7.4
PREHEAT AND DHW FUNCTION
POWER
SWITCH
ON
BLUE
LIGHT
ON
LOCKOUT
PREHEA
T
DEMAND
YES
NO
NO
YES
ECO button not
illuminated *
(i.e. preheat requested)
Burner threshold
during pre-heat.
Burner ON:
Supply temperature
< DHW setpoint -5K
AND
20 minutes since last
pre-heat demand.
Burner OFF:
Supply temperature
> DHW se 5K
*Set by pressing ECO
button, if proprammer
is fitted this is set by a
combination of
progarmmer
(DHW) demand
and ECO button.
Diverter value
in DHW
position
Pump ON.
5th
attempt?
Spark
ignition
4 seconds
Stop spark.
W
ait
10 seconds
BURNER
LIT?
IGNITION
SEQUENCE
(see details)
GREEN
FLAME
LIGHT
ON
DEMAND
END
DEMAND
END
Fan (& gas)
modulation
to achieve
set
temperature
(40-60
0
C)
Over temperature
shut-down if water
temperature is10
0
C
above set value.
Burner shut down if
primary temperature
95
0
C
Diverter value opens
to CH
Fan (& gas)
modulation
to achieve
(40-60
0
C)
Gas value OFF
.
Pump overrun
(post purge) is
30 seconds
in DHW
.
Fan runs
30 seconds
Gas value
OFF
Stop pump
Stop fan
IGNITION SEQUENCE
Fan
start
speed.
W
ait
5 seconds
Gas value OFF
.
T
ap open
(recognised
by flow
turbine)
DOMESTIC
HOT
WA
T
E
R
DEMAND
(priority over
all other
demands)
6720647361-60.2Wo
