AquaStar Bosch 125B Thermocouple Replacement and Troubleshooting Manual

Mineral Scale Buildup:AquaStars, when operated at high temperatures or in hard water areas, may need periodic descaling. To check the inside of the heat exchanger for scaling, remove the thermostat sensing element from inside the heat exchanger (B), page 6. If you note mineral buildup in the heat exchanger, flush it with a descaling solution. Consult your dealer or call CEC for instructions.

TROUBLE SHOOTING

Letter references, e.g. "L" in this section refer to Fig. 2 on page 6.

Introduction: The flow of gas to the AquaStar burners is triggered by a water flow valve. Numerous water related problems can cause this water flow valve to malfunction such as:

1.Insufficient water flow volume to activate the burners at their minimum flow requirement

2.Dirt in the water flow valve causing the valve to malfunction

3.Sediment buildup in faucet aerators or shower heads preventing minimum flow requirement

4.Uneven pressures between cold and hot (with single lever faucets)

5.Plumbing cross-overs

These water related problems can cause the heater to deliver less than its full output, or to shut down completely.

SPECIFIC PROBLEMS AND ANSWERS Note: Problems are stated in upper case, bold face. Most common causes for the problems follow in order of likelihood of occurence. For most of the suggested solutions, it will be nec- essary to take the front cover of the heater off. To do this, pull the knobs off and remove the 3 screws at front of panel, then lift and pull the front panel off. It is also advisable to remove the bottom tray: Pull off the plastic handle of the manual gas valve and remove the 4 bottom screws. The tray will drop down.

PILOT WILL NOT LIGHT

1. No gas to the AquaStar

A. Gas cock on gas line may not be open.

B. AquaStar manual shut off valve at base of heater is not open. Turn handle to red flame sym- bol.

2.In-line AquaStar gas regulator jammed (usually with LP gas)

Replace or unjam the regulator. Note: The regu- lator furnished with the heater is designed for low gas pressure. Excessive pressure will lock it up. This problem usually happens if the gas pressure between the gas tank and the water heater has not been reduced. See page 3 of your manual for specified gas pressures.

To unjam a regulator, remove the nickel size screw plug on the front. Inside you will see another large screw. Draw a line down the threads to mark the location of the screw. Re- move the screw and push on the bottom of the hole with the eraser side of a pencil or similar object. This will release the diaphragm. Rein- sert the screw and screw it down to the end of the mark you made.

3.Pilot orifice cloggged and/or air screen dirty, or pilot filter is dirty.

Clean the pilot orifice and/or pilot filter screen. Disconnect the pilot tube (T) by unscrewing it. Be careful not to misplace the small washers. The diagram on page 19 shows how the parts of the pilot assembly fit together.

Natural gas orifices are large enough that you can usually clean them by blowing through them. The LP orifice is so small that it is best to replace it. Never try to enlarge the hole, or use a sharp hard object for cleaning. Doing so will ruin the orifice.

The pilot gas filter is made from a layered ma- terial. If it becomes too dirty, a portion of the filter can be separated and peeled off. The clean portion should be loosely reinserted into the pilot burner brass filter chamber. Be careful when re-installing the pilot burner to aim the burner so that the smaller right hand pilot flame touches the thermocouple tip.

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