6 720 646 812
Troubleshooting
47
7
Troubleshooting
7.1
Introduction
Many of the questions customers ask regarding operation
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 troubleshooting.
For best results, perform each step before proceeding 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
water is turned ON
It is recommended to use “Control board diagnostics”
page 46
,
chapter 6.7
as a tool for problem solving.
1. If the display is blank, verify power to outlet. (120VAC/
60Hz properly grounded circuit required). Verify that the
heater power button is pressed ON.
2. Verify the fuses in the control board are good. To
access fuses, the control board must be removed. See
chapter 4.2
,
page 36
.
3. Make sure cold water inlet connection is plumbed to the
right side of heater when facing unit. See Fig.
32
,
page
29
.
4. A minimum of 0.5
gallons per minute (GPM) (1,9 l/m) is
required to activate the heater. A quart container should
fill in 23 seconds or less, from hot water tap only, to
activate heater.
5. Clean inlet filter screen per chapter
3.9
,
page 29
.
6. Inspect the water path for obstructions. Make sure all
showerheads, faucet aerators and whole house filters
are clear of debris.
7. The heater activates when the water flow through the
unit is at or above the required minimum of 0.5 GPM
(1,9 l/m). A crossover in the hot and cold plumbing
pipes creates back pressure on the water flowing
through the heater. Therefore, a higher flow rate than
normal is needed to force the heater to activate. To
check for a plumbing crossover, shut off the cold water
supply to the water heater. Then open all of the hot
water taps served by the heater. Wait 10 minutes and
check for water flow at each tap. There should be no
water flowing. Any continuous flow of water, small or
large, indicates a crossover is present and must be
corrected. Consult a professional plumber for help in
correcting a crossover. Failing single lever faucet mixing
valves are common causes of plumbing crossovers.
8. With the power button pressed switch turned to OFF
and the power supply cord unplugged, remove the
unit's front cover (See Page
7
. Fig
3
). Check wire
connections between the water valve, control unit and
electrode set. See chapter
12.2
,
page 59
for location
of these parts.
9.
Water heater in solar mode. If inlet water temperatures
exceed the water heater's set temperature, the burners
will not ignite and the solar mode indicator will show on
the display. See
Fig. 54
,
page 37
.
7.3
Water is too hot
1.
Selected temperature on the unit is too high. To lower
output temperature, see chapter
5.4
,
page 38
.
2. Clean inlet filter screen per chapter
6.1
,
page 41
to
increase flow through the heater.
3. Inspect the water path for obstructions. Make sure all
showerheads, faucet aerators and whole house filters
are clear of debris.
4. Confirm the heater's gas type coincides with the type of
gas being supplied. See Fig.
2
,
page 6
for location of
rating plate.
5. Avoid restrictive outlets. Clean all showerheads and
faucet aerators. It may be necessary to upgrade to
higher flow rate shower heads if allowable by local
code.
6. In areas where the water has a high mineral content,
periodic descaling may necessary. See chapter
6.3
,
page 42
for directions.
7.
Ensure the temperature sensor is making contact and
firmly mounted on the hot water pipe.
7.4
Water is not hot enough
1.
Selected temperature on the unit is too low. To raise
output temperature, see chapter
5.4
,
page 38
.
2. Clean inlet filter screen. See chapter
6.1
,
page 41
to
increase flow through the heater.
3. Inspect the water path for obstructions. Make sure all
showerheads, faucet aerators and whole house filters
are clear of debris.
4. Confirm the heater's gas type coincides with the type of
gas being supplied. See Fig.
2
,
page 6
for location of
rating plate.
5. Check inlet gas particle screen for blockage at gas inlet
connection on bottom of unit.
6. Verify gas pressure is in accordance with specifications
in chapter
3.14
,
page 35
. A gas pressure reading is
needed to proceed further. Contact your original
installer or a local certified gas technician to obtain this
reading.
7. Cold water is mixing into the hot water lines (plumbing
crossover). A plumbing crossover can unintentionally
mix cold water with the hot water leaving the heater. The
end result is a cooler water temperature than desired.
To check for a plumbing crossover, shut off the cold
water supply to the water heater. Then open all of the
hot water taps served by the heater. Wait 10 minutes
Warning:
If you are unable to perform
the tasks listed below, or need
additional assistance please contact
your original installer or a licensed gas
technician.
Summary of Contents for C1050ES
Page 56: ...6 720 646 812 56 Functional scheme 11 Functional scheme Fig 76 Functional scheme ...
Page 58: ...6 720 646 812 58 Interior components diagram and parts list Fig 78 Appliance overview ...
Page 69: ...6 720 646 812 Notes 69 15 Notes ...
Page 70: ...6 720 646 812 70 Notes ...
Page 71: ...6 720 646 812 Notes 71 ...
