Bosch C1210ES Specifications download pdf (Page 42)

42 | Troubleshooting

C 1210 ES/ESC6 720 644 887 (2014/11)

8Troubleshooting

8.1 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 fig. 3, page 8).

8.2 Burner does not ignite when hot water is turned ON

It is recommended to use “Control board diagnostics” page 41, chapter

7.7 as a tool for problem solving. If the display is showing a blinking two

digit code, refer to this section.

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 5.2, page 33.

3. Make sure cold water inlet connection is plumbed to the right side of

heater when facing unit. See Fig.31, page 28.

4. A minimum of 0.5 gallons per minute (1.9 l/m) of hot water demand

is required to activate the heater. Confirm at least 0.5 gpm flow by

timing how long it takes to fill a container. A quart container should fill

in 23 seconds or less, from hot water tap only, to activate heater. In

unusual circumstances with high inlet water temperatures and low

set temperatures, the heater may increase the activation rate above

0.5 gpm to avoid overheating at low flows. Gradually increase water

flow (hot water demand) through the heater to determine if the

heater activates with higher flow.

5. Clean inlet filter screen per chapter 4.9, page 28.

6. Inspect the water path for obstructions. Make sure all shower heads,

faucet aerators and whole house filters are clear of debris.

7. Check for plumbing crossover. 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 fig. 3,

page 8). Check wire connections between the water valve, control

unit and electrode set. See chapter13.2, page 53 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. 53, page 34.

8.3 Water is too hot

1. Selected temperature on the unit is too high. To lower output

temperature, see chapter6.4, page 34.

2. Clean inlet filter screen per chapter7.1, page 36 to increase flow

through the heater.

3. Inspect the water path for obstructions. Make sure all shower heads,

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 8 for location of rating plate.

5. Avoid restrictive outlets. Clean all shower heads 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 chapter7.3, page 37 for directions.

8.4 Water is not hot enough

1. Selected temperature on the unit is too low. To raise output

temperature, see chapter6.4, page 34.

2. Clean inlet filter screen. See chapter7.1, page 36 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 8 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

chapter4.14, page 32. 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 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 correcting a crossover. Failing

single lever faucet mixing valves are common causes of plumbing

crossovers.

8.5 Low water flow/pressure

1. Too many hot water applications are being used simultaneously or

too much flow is demanded. The water heater will effectively support

two 2.0-2.5 GPM shower heads simultaneously or multiple sink

applications. Greater draws will result in a water pressure drop and

reduced flow at taps.

2. Ensure that gas pressure is in accordance with specifications in

chapter4.14, page 32. A gas pressure reading is needed to proceed

further. Contact your original installer or a local certified gas

technician to obtain this reading. If gas pressure is inadequate, the

water heater will close its motorized water valve, reducing the hot

water flow rate in an attempt to reach the selected output

temperature.

3. If selected temperature on the unit is set too high for the demanded

flow rate, the water heater will close its motorized water valve,

reducing the hot water flow rate in an attempt to reach the selected

output temperature. Lowering the selected temperature will allow

the motorized water valve to open up for increased water flow rate.

4. Clean inlet filter screen per chapter 7.1, page 36.

5. Inspect the water path for obstructions. Make sure all shower heads,

faucet aerators and whole house filters are clear of debris.

WARNING:

▶ If you are unable to perform the tasks listed below, or

need additional assistance please contact a qualified

gas technician.

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Bosch C1210ES Specifications Page 42

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