Bosch C 1050 Manual

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Problem solving51
Exhaust  temperature  sensor  -  the 
appliance will close the burner and 
lock  if  it  gets  over  194°F;  (only 
applied for condensing unit). 1. Clean and check heat exchanger.
2. Clean and check condensing heat exchanger. 
3. Reduce maximum power (
chapter 3.14, page 35).
4. Reduce water temperature.
Backflow  temperature  sensor  over 
309°F. 
The appliance will close the burner 
and lock (non-volatile). 1. Check inlet/outlet vent pipes.
2. Check if secondary fan...

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Problem solving
Ionization failure during operation. 1. Check gas ty
pe, Fig. 2, page 6.
2.  Check  three  wire  connections  to  ignition  group  o n  the  lower
front of the heat exchanger are secure. 
3. Verify that venting specifications are met. Impr oper venting may
cause premature failure of the flame sensor rod. See  
chapter 3.3,
page 10.
4. Check gas pressure. See 
chapter 3.14, page 35.
5. Check and adjust CO2 readings. See chapter 6.5, page 43.
6.  Check that the minimum power...

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Electrical diagram53
9 Electrical diagram
Fig. 72 Electrical scheme
1Intlet water temperature sensor
2 Outlet water temperature sensor
3 Backflow temperature sensor
4 Cascading output connection
5 Cascading input connection
6 Ionization sensor
7 Water flow sensor
8 Flue gas limiter
9 Heat exchanger overheat sensor (ECO)
10 Gas valve
11 Exhaust temperature sensor
12 Water valve
13 Primary fan
14 ON/OFF switch
15 Secondary fan
16 AC plug
17 Main connection
18 Ignition electrodes
19 Ground...

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Sensor resistance charts
10 Sensor resistance charts
Fig. 73 
Fig. 74
Outlet NTC characteristics
3 2
3 7
4 2 4 7
5 2 5 7
6 2 6 7
7 2
7 7
8 2 8 7
9 2 9 7
10 2 10 7
112117
12 2 12 7
13 2 13 7
14 2 14 7
15 2
15 7
16 2 16 7
17 2 17 7
18 2 18 7
19 2 19 7
2 0 2 2 0 7
2 122 17
2 2 2
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 2 0 2 1 2 2 2 3 2 4 2 5 2 6 2 7 2 8 2 9 3 0 3 1 3 2 3 3 3 4 3 5 3 6 3 7
Re sista nce  (Kohm)
Temp ºF
0
5
10
15
2 0
2 5
3 0
3 5
4 0
4 5
5 0
5 5
6 0
6 5
7 0
7 5
8 0
8...

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Sensor resistance charts55
Fig. 75
Back Flow and Exhaust NTC characteristics
3 2
3 7
4 2
4 7
5 2
5 7
6 2
6 7
7 2
7 7
8 2
8 7
9 2
9 7
10 2
10 7 112
117
12 2
12 7
13 2
13 7
14 2
14 7
15 2
15 7
16 2
16 7
17 2
17 7
18 2
18 7
19 2
19 7
2 0 2
2 0 7 2 12
2 17
2 2 2
2 2 7
2 3 2
2 3 7
2 4 2
2 4 7
2 5 2
2 5 7
2 6 2
2 6 7
2 7 2
2 7 7
2 8 2
2 8 7
2 9 2
2 9 7
3 0 2
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 3 0 31 32 33 34 35 36 37
Re sista nce  (Kohm)
Temp ºF
0
5...

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Functional scheme
11 Functional scheme
Fig. 76 Functional scheme
Fanspeed
OK? waiting
timeof10s passed?
watertap
open?Waterflow 0.5gpm
(>1.9l/min)
(seeWFcalc.) >
NO NO NO NO
YES
YES
YES
YES
NO NO NO
NO
YES YES
Startsparking
IDLE
Openthegas
valve
1st
Safetytime
of5spassed?
Ionization
detected?
6720608158-65.2V
NO
NO
NO
NO YES
YES
YES Seeerror
codetable
Postpurgeof fanfor7sec.
Stayblocked tillRESET
closesecond gasvalve
Postpurgeof fanfor7sec.
watertap
closed

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Interior components diagram and parts list57
12 Interior components diagram and parts list
12.1 Interior components
Fig. 77 Components
1Exhaust temperature sensor
2 Flue gas collector
3 Heat exchanger
4 Ionization sensor
5 Primary fan (Mixer)
6 Hot water temperature sensor
7 LCD display
8 On/Off button
9 Reset button
10 Program key
11 Flue gas limiter
12 Heat exchanger overheat sensor (ECO) 13
Ignition electrodes
14 Observation window
15 Backflow temperature sensor
16 Secondary air fan
17...

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Interior components diagram and parts list 
Fig. 78 Appliance overview 

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Interior components diagram and parts list59
12.2 Components diagram
12.2.1 Group 1 
Fig. 79 Components Diagram
9
9
8
5
12
3
6
7
9
10
12
9
14
16
17
11
1315
15
4
6720902973.AB JF
ItemDescriptionReference
1 Front cover 8 705 431 412 
2 Cover shield 8 705 506 906
3 Trade mark badge 8 701 103 140 
4 Cover screw 8 703 401 170 
5 Combustion cover 8 700 506 300
6 Combustion cover gasket 8 704 701 084
7 Observation window 8 705 600 003 
8 Holding bracket 8 708 104 103 
9 Screw 8 703 403 012
Table...

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Interior components diagram and parts list 
12.2.2 Group 2 
Fig. 80 Components Diagram
1230
25
13
15
20
1
4
5
6
7
32
8
9
10
8
8
11
11
8
1214
21
22
13
18
17
16
16
1319
172324
2728
28
2829
31
32
33
35
26
6720902980.AA JF
34
13