Bosch Worcester 15SBi - Operational Flow Diagrams

30
17. Operational Flow Diagram
Facia
light
ON
BOILER
HEAT
DEMAND
If HL stat
has tripped,
4 second
delay
CH only
demand
CH selected
on timer &
room calling.
In addition for
Y plan:
DHW selected
on timer &
tank satisfied
or
DHW off
signal from
timer.
Pump
continues
for
3
minutes
DEMAND
END
DHW only
demand
DHW selected
on timer, tank
stat calling
DHW & CH
demand
DHW & CH
selected on
timer, tank
stat calling,
room stat
calling.
Facia control
knob above
position 'I'
Fan
ON
Pump
ON
20
second
delay
Reset
on
facia
APS
ON
LOCKOUT
(all outputs OFF
EXCEPT pump)
Gas valve
and
sparking
ON
Flame
sense
No flame
sense for
8
seconds
Burner ON.
This sequence
is cycled to
satisfy
temperature
set by facia
control knob.
Temperature
Sensor disconnected.
Fan and burner OFF.
Pump running.
Failed ignition
Overheat of
gas to water
heat exchanger
Overheat
thermostat
trip.
Gas valve not
energised during
ignition recycle.
Burner
LOCKOUT
Reset
using facia
red button
CH = Central Heating DHW = Domestic Hot Water
Protection Systems