Functional Scheme - Bosch Therm 8000 S Installation And Operating Instructions Manual

11 Functional scheme

Water flow
> 0.5 gpm
(> 1.9 l/min)
(see WF calc.)
Fan speed = correct
Ionization = off
Temp. limiter = closed
Temp. sensors = ok
Over heat protection = ok
INPUTS:
- FANSPEED
- WATER TEMP.
- WATERFLOW
OUTPUTS:
- FANSPEED
- WATERFLOW
close one gas
valve
flame off?
Fig. 64
Therm 8000S
IDLE
water tap
NO
open?
YES
Appliance
NO
ready to start?
YES
NO
Fan speed
NO
OK?
YES
Start sparking
Open the gas
NO
valve
Ionization
NO
detected?
YES
Hot water
delivered at
selected temp.
YES
safety
NO
devices
OK?
YES
water tap
closed
NO
<0.5 gpm?
YES
NO
waiting
time of
YES
1s passed?
NO
YES
waiting
time of 10s
passed?
NO
1st
2nd
Safety time
Safety time of
YES
of 5s passed?
5s passed?
close second
gas valve
Post purge of
fan for 7 sec.
6720608158-65.2V
Functional scheme | 45
See error code table
YES
NO
3rd
Safety time
YES
of 5s passed?
YES
See error
code table
Post purge of
fan for 7 sec.
Stay blocked
till RESET
Water flow
Calculus
Minimum Power
WF =
(Set point - Inlet)
0.5 GPM < WF < 1.6 GPM
WF > 1.6 GPM
NO
(2 l/min < WF <6 l/min)
(WF > 6 l/min)
YES
YES
Burner ON
Burner ON
Burner shutdown at:
Burner shutdown at:
Set point +14°F (8°C)
Set point +9°F (5°C)
WF < 0.45 gpm ± 0.05 gpm WF < 0.45 gpm ± 0.05 gpm
(WF < 1.7 l/min ± 0.2 l/min)
(WF < 1.7 l/min ± 0.2 l/min)
Water flow procedure
6 720 680 174 (2014/05)
NO