Bosch Appliances WR430-3K manual Trouble Shooting, Maintenance and Service

MAINTENANCE AND SERVICE

Approximately once a year, the Bosch should be checked, cleaned and serviced as necessary. To remove the front cover, first remove the incandescent particle tray, then pull off the temperature adjustment knob and unscrew and remove the plastic collar. Pull main cover out toward you and lift up and out. THE FOLLOWING OPERATIONS SHOULD BE PERFORMED BY A QUALIFIED SERVICE PERSON:

Vent System: Should be checked annually. Clean and repair as needed. See Preventative Maintenance Page 10.

Water Valve: The water valve on this heater should be serviced periodically. The frequency will depend on the mineral content of the water and conditions of use or whenever signs of corrosion appear at the gas and water valve joint. Check that the water inlet filter (#36 on Figure 19, page 20) is clean. Diaphragm should be replaced every 7-8 yrs. in residential applications and 3-5 yrs for commercial applications. In acid water areas the venturi should also be replaced at the same time (#39 on Figure 19, page 20).

Pilot Flame: The pilot flame should burn with a clean, sharp, blue flame and should resemble the diagram in Fig.

13.If the flame is soft and yellow the pilot screen may be dirty or the pilot burner orifice may need to be cleaned or replaced. The pilot flame should be approximately 2 inches long, extending past the flame sensor. If the flame is too small, it will not reach the flame sensor and the burners will not come on.

3mm

Correct gap between pilot burner tip and electrode tip

Electrode

Pilot cap orifice

Pilot tube

Flame sensor

Electrode

Fig. 13 - Characteristic Pilot Flame

To clean the pilot burner and/or the pilot orifice: Turn off the gas to the unit. Set the On/Off switch to Off ( position 0). Remove the cover of the heater. To do so, pull off the temperature adjustment knob and unscrew and remove the plastic collar. Pull main cover out toward you and lift up and out. The pilot orifice should be cleaned or replaced.

Do not enlarge the orifice.

Do not use any wire or sharp object to clean orifices. Natural gas orifices are large enough that you can usually clean them by blowing through them. To access the pilot orifice, remove 2 screws holding pilot assembly in place. Then loosen compression fittings to expose pilot orifice.

Heat Exchanger should be visually examined once a year or more often in dusty areas. If fins at top show dust or debris accumulation, remove and clean with brush and soapy water.

Removal of the Heat Exchanger

1. Shut off the gas and water cold supply lines to the heater and remove the front cover.

2. Remove the drain screw from the bottom of the water regulator and open the hot water tap to allow the unit to drain.

3. Remove cover and unscrew metal retaining bar at the top front of the heat exchanger

4. Undo water connection nuts at

heat exchanger from both sides

5. Tilt the heating body to the front at the top and lift away from the heater.

Estimated service time is 10 minutes to re & re, plus cleaning time

Main Burner Flames: The main burner flames should be blue, with a more intense blue cone in the center core. Yellow flames could be a sign of plugged or dirty burners, or a blockage on the heat exchangers fins. If some burners have yellow flames while others have good flames, it is likely that dust, lint or spider webs have partially clogged the burner venturis. To clean the burners, contact a gas service person.

Mineral Scale Build-up: In hard water areas the Bosch, when operated at lower temperature settings, tend not to accumulate mineral buildup. If however, the heater is used at the higher temperature settings and the water has a high mineral content, periodic descaling may be necessary. The heating coil should be removed and flushed with a descaling solution. Signs of scaling are rising outlet temperature and knocking noises when water is flowing.

TROUBLE SHOOTING

Introduction

The Bosch WR430-3K burners are activated by a water flow valve. Numerous water related problems can cause this water valve to malfunction such as: Insufficient water flow volume to activate the burners at its minimum flow requirement; Dirt in the water flow valve causing it to malfunction; Sediment build-up in faucet aerators, or shower heads; Uneven pressures between cold and hot, (with single lever faucets) Plumbing cross overs. These water flow related problems can cause the heater to deliver less than its full output, or to fail to ignite or to shut down completely.

Problems are stated in upper case, bold face. Most common causes for the problems follow in order of likelihood. The suggested solutions require that the cover be taken off. To do this, remove incandescent particle tray, pull off the temperature adjustment knob and unscrew and remove the plastic collar. Pull main cover out toward you and lift up and out.

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