9gis – A.O. Smith 120 through 250 Series User Manual
Page 56
Starting and running
56
Instruction manual BFC
9
gis
Once the appliance starts, it will run through the
following steps:
1. The water temperature drops below the set
temperature of (for example) 65°C. The electronic
controller detects a demand and starts the heating
cycle.
-
The icon is activated.
-
The message HEAT DEMAND appears.
2. Once demand is registered, the fan is started to
exhaust any gases that may be present. This
phase is called pre-purge and lasts about 15
seconds.
-
The icon is activated.
-
The message PRE PURGE appears.
3. During the pre-purge, the pressure switch closes.
-
The icon is activated.
-
The message PRESSURE SWITCH
appears.
4. After some time, the pre-purge ceases and the
electronic controller reduces the fan speed to the
ignition speed. This is followed by the (pre-)glow of
the hot surface igniter.
-
The icons and are dimmed
-
The icon is activated.
5. After a number of seconds pre-glow, the gas
control is opened and ignition takes place.
-
The icon is activated.
-
The message IGNITION appears.
6. After ignition, the flame is detected and the
appliance will be running. This means that actual
heating has started. The fan speed then increases
to the normal working speed, and the pressure
switch closes:
-
The icon is dimmed.
-
The icons and are activated.
-
The message RUNNING appears.
7. When the water is up to temperature, the heat
demand drops off and the post-purge starts. This
lasts about 25 seconds.
-
The icons , and are dimmed.
-
The icon is activated.
-
The message POST PURGE appears.
8. Following the post-purge, the fan stops and the
pressure switch opens:
-
The icons and are dimmed.
-
The message POST PURGE vanishes.
With any subsequent heat demand, the heating cycle
will resume from step 1.
ON
Ê
13:45 Thursday
63ÉC
Tset 65ÉC
HEAT DEMAND
ON
К К
13:45 Thursday
63ÉC
Tset 65ÉC
PRE PURGE
ON
К К К
13:45 Thursday
63ÉC
Tset 65ÉC
PRESSURE SWITCH
ON
К
К
13:45 Thursday
63ÉC
Tset 65ÉC
GLOW PLUG
a
a
a
a
ON
К
К К
13:45 Thursday
63ÉC
Tset 65ÉC
IGNITION
ON
К
К
К К
13:45 Thursday
63ÉC
Tset 65ÉC
RUNNING
ON
К К
13:45 Thursday
65ÉC
Tset 65ÉC
POST PURGE
ON
14:05 Thursday
65ÉC
a
a
a
a