Bosch Appliances 125B NG, 125B LP specifications AIR Screen Pilot Orifice

Water Valve (Part # 8707002649): The water valve on this heater should be serviced periodically. Lubricate component #23 on page 19 with a small amount of silicon, faucet or lithium grease every two years to keep its o rings fresh and pushrod sliding smoothly. Every 3-5 years replace component #23 on page 19. 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. Periodically check that the water inlet filter (#25 on page 19) is clean as well.

NOTE: If water valve is removed, be sure to also inspect the o ring seal on the end of the right hand side water pipe before re-installing. Lubricating the o ring with lithium or faucet and valve grease is recommended.

Pilot Flame: The pilot flame should burn with a clean sharp blue flame and should resemble the diagram in Fig 10. If the flame is yellow, or if the pilot knob has to remain depressed for a long time in order to keep the pilot lighted, the pilot burner and or the pilot burner orifice may need to be cleaned, the orifice may need to be replaced, and or the air screen may need cleaning. The pilot flame should envelop approximately 10 mm (3/8") of the tip of the thermocouple. If it is too small, the pilot burner must be cleaned. To obtain a spark, the position of the Piezo igniter electrode should be approximately 3 mm (1/8") from the pilot burner tip.

3mm

Correct gap between pilot burner tip and electrode tip

Piezo Electrode

Air screen filter

10mm 3/8”

Thermocouple

Piezo

Electrode

Fig. 10 - Characteristic Pilot Flame

To clean the pilot burner and/ or the pilot orifice : Turn off the gas at the unit. Remove the cover of the heater. To do so, pull off the temperature adjustment knob and unscrew and remove the plastic collar and unscrew the central screw located at the bottom of the front cover. Pull main cover out toward you and lift up and out . Pull the air screen off, wash it and blow any lint off (See Fig 11). The pilot orifices should also 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. LP orifices, on the other hand, are too small to clean and should be replaced. See #3 in Trouble Shooting Section.

To access the pilot orifice, remove 2 screws holding pilot assembly in place. Then loosen compression fittings to expose pilot orifice.

AIR SCREEN

PILOT ORIFICE

Fig. 11 - Pilot burner with air screen/ pilot orifice

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 wrong size gas orifices 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: The AquaStar heater, when operated at lower temperatures settings, does not accumulate mineral build-up. 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 coils should be flushed with a descaling solution. Consult your dealer or Controlled Energy for instructions.

Consult your service person.

TROUBLE SHOOTING (see maintenance table)

Introduction

The AquaStar 125B 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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