Bosch Appliances 125HX NG Pilot Lights but Burners will not Come on, Water is TOO HOT

PILOT LIGHTS BUT BURNERS WILL NOT COME ON

1.Confirm water valve assembly is working properly.

2.Confirm the flame sensor is in its proper position.

3.Confirm the burner electrovalve switch is functioning properly.

Call CEC

4.The Electronic Control Box (Fig. 13) may need to be replaced.

Call CEC.

Fig. 13 - Electrical wiring diagram

1	burner electrovalve	8	electronic control box
2	gas control valve	9	LED failure indicator
3	pilot electrovalve	10	LED indicator main
4	flame sensor		burner operation
5	pilot electrode	11	on/off switch
6	overheat sensor	12	hydro-generator
7	temperature limiter	13	flue gas safety device

MAIN BURNERS GO OUT DURING HOT WATER USE

1.Flow rate diminished below activation rate

2.Unbalanced pressure in the water lines

The added restriction caused by the AquaStar in the hot water system can result in uneven pressures between the cold and the hot. In such cases when mixing cold water at the tap, the lower hot water pressure may be overpowered by a much higher cold water pressure, which may cause the AquaStar burners to shut down. Make sure faucet aerators and showerheads are free of minerals and dirt. Do not add any flow restrictor to the shower head.

3.Minimum inlet pressure on well is inadequate Check the inlet water pressure. On a private well, raise the minimum pressure setting to 30 psi. Confirm that the pressure tank is not water logged.

4.ECO (overheat sensor) tripped due to overheating re-ignite the appliance 10 minutes later. If it happens again, contact your service person or Controlled Energy.

5. Flue gas safety device tripped

Ventilate the room and re-ignite the appliance 10 minutes later. If it happens again, contact your service person or Controlled Energy..

WATER IS TOO HOT

1. Temperature Selection too high

Turn the temperature adjustment knob counter-clockwise (to the left) to lower the maximum water temperature.

Note: This will increase the activation flow rate.

2.Inlet water temperature is too hot (as with solar preheated water or high ground water temperatures)

Decrease gas pressure. Note: Only the Model “S” AquaStar should be used if the inlet water is preheated.

WATER IS NOT HOT ENOUGH

1. Temperature selection too low.

Change the setting. Turn the temperature adjustment knob clockwise (to the right).

Note: This will decrease the activation flow rate.

2.Btu input is too low due to insufficient gas pressure It is extremely important for a tankless instantaneous water heater to have the right size gas line to obtain the correct gas pressure

See specifications on page 2. Unlike storage tank water heaters, the burners of a tankless water heater must be very powerful to heat water instantaneously since they do this only at the time hot water is actually being used. It is therefore imperative that the gas pressure requirement be met exactly. Insufficient gas pressure will directly affect the water temperature at the time of usage. See page 2 for correct gas pressure settings and fig. 4 for locations where gas pressures are taken.

3.Btu input is too low due to insufficient gas supply Make sure your main gas line is fully opened. If using LP gas, be sure that the size of the propane tank is adequate to supply the required gas pressure.

4.Cold water is mixing with the hot water between the AquaStar and the outlet

Compare water temperature at outlet of the AquaStar (hold the AquaStar’s outlet pipe with your hand) and at the tap. If these two are very different, check for mixing valve or plumbing crossover (see “NO SPARK AT THE PILOT” paragraph #4). Where automatic “anti-scald” valves are required by code, lower the temperature setting on the AquaStar as much as possible and balance the pressure between cold and hot water after the AquaStar.

5.Parts in water flow valve are corroded so that the gas passage is not fully opening.

Contact your service person or Controlled Energy.

6 720 606 804 (02.10) 13