Bosch C 1050 Manual

6 720 644 894
Maintenance and service41
6 Maintenance and service
6.1 Annual maintenance
(To remove front cover, see page 7.) 
Venting System 
• Venting  system  -  inspect  inside  of  flue  pipe  for  a ny
blockage  or  restriction.  Observe  burner  flames 
during  heater  operation.  (front  cover  must  be
removed).  Inspect  the  combustion  air  inlet  pipe  for
blockage  or  debris.  Inspect  combustion  air  and
exhaust terminations for blockage or debris.
Combustion Chamber 
• Inspect burner...

6 720 644 89442
Maintenance and service 
5. Disconnect  inlet  and  outlet  water  pipes  from  the
water  heater.  Place  a  small  bucket  underneath  the 
water heater to catch residual water remaining insi de
the water heater.
6. Using  an  air  compressor,  blow  short  bursts  of  air (100psi max) through the inlet water connection unt il
there is no water present coming  through  the outlet
water connection of the heater.
7. Reconnect water fittings and return heater to ser vice
when danger of...

6 720 644 894
Maintenance and service43
B
Remove  the  condensing  heat  exchanger  unit  from 
the appliance by pulling it towards you.
B Dismantle all parts for inspection and cleaning.
Fig. 67 Condensing heat exchanger B Check  the  condensing  heat  exchanger  for  any 
obstruction.
B Flush the condensing heat exchanger unit with water .
B Check all gasket and o-rings for damage and replace  
if necessary.
B Assemble the condensate unit and all other parts in  
reverse order of disassembly.
6.5...

6 720 644 89444
Maintenance and service 
Note:  When  making  adjustments,  make  sure 
combustion cover is installed. 
C. Adjusting CO
2:
Note: P1 adjustment will change the P2  reading. 
Confirm  the  P1  value  BEFORE  adjusting  the  P2
level. 
1. If P1 CO
2 level is off:
B Loosen  yellow  painted  Phillips  screw  (1)  and  cover 
should  rotate  down  (2)  revealing  a  recessed  brass
slotted screw. Fig. 70.
B Turning  the  slotted  screw  counter  clockwise  will
raise  P1  CO
2  levels  and...

6 720 644 894
Maintenance and service45
6.6 Program values
This section describes details on programming the  
appliance. For most applications the factory defaul t val-
ues will provide robust and stable operation. Only 
adjust the factory settings if the installation req uires 
changes as indicated in the appropriate section of  this 
manual. Refer to  6.7 Control board diagnostics (page 35) 
regarding how to access these P-modes.
Caution:  Misadjusted  program 
values  can  lead  to  appliance...

6 720 644 89446
Maintenance and service
6.7 Control board diagnostics
1. Press ON/OFF button to turn off the appliance. 
2. Press  and  hold  Program    button  and  press
ON/OFF button to turn appliance ON.
3. Release the   button when 188 appears on the display.  The  display  should  read  P2  when  the 
program button is released. If not, repeat process.
4. Press  and  release  the    button  on  the  control panel until the display reads P4. You are now in  the
diagnostic mode of the control board....

6 720 644 894
Troubleshooting47
7 Troubleshooting
7.1 Introduction
Many of the questions customers ask regarding opera tion
of  this  unit  can  be  answered  by  following  the 
troubleshooting steps as outlined below. Visit our  web site
at  www.boschpro.com  for  more  detailed  troubleshooti ng.
For best  results,  perform  each  step  before proceedi ng to
the  next.  The  suggested  solutions  may  require  that  the
cover be taken off. (See Page 
7. Fig. 3).
7.2 Burner does not ignite when hot...

6 720 644 89448
Troubleshooting
and  check  all  taps  for  water  flow.  There  should  be 
no
water  flowing.    Any  continuous  flow  of  water,  small  or
large,  indicates  a  crossover  and  must  be  corrected. 
Consult a professional plumber for help in correcti ng a
crossover.  Failing  single  lever  faucet  mixing  valve s  are
common causes of plumbing crossovers.
8.Ensure the temperature sensor is making contact and  
firmly mounted on the hot water pipe.
7.5 Low water flow/pressure
1.Too...

6 720 644 894
Problem solving49
8 Problem solving
8.1 Error code diagnostics
i
To  remove  error  code  from  the 
display, press the reset button.
DisplayCauseSolution
Fault in the flue gas limiter. 
Temperature  above  230 °F 
(110 °C) inside the cabinet. 1. Check continuity of the flue gas limiter (see Fig. 77, page 57).
Go  to  steps  two  and  three  to  determine  flue  gas  lim iter  fault  and
repair it. 
2. Check for flue gas leakage around the top and bo ttom seals of
heat exchanger, use mirror...

6 720 644 89450
Problem solving
Primary  fan  rotation  too  low  in 
operation.
1.  Disconnect  power  supply  cord  and  check  wire  conn
ection  on
back side of fan and the connectors on the control  board, see 
Fig.
84
, page 65.
2.  Check  supply  voltage.  It  must  be  120VAC  and  prop erly
grounded. 
3.  Check  venting  specifications  are  met.  Long  vent  lengths,
venting with more than three elbows, blocked vent o r combination
venting may cause this failure.
4.  Ensure  intake  and...