A.O. Smith BTI 100 G Operation of the storage water heater, Normal operation, Ignition failure

1.2.3Operation of the storage water heater.

Normal operation

When there is a demand for heat a waiting period of about 1 second elapses before the built-in spark gene- rator and pilot gas valve are switched on. The ignition sparks ignite the pilot burner and the resulting flame is detected by the ionisation electrode. Almost immediately after the pilot flame is detected, sparking stops and the main gas valve is openend. The main burner is lit by the pilot flame. The unit is now in operation. When the temperature of the water in the unit reaches the temperature that is set with the thermostat, the thermostat switches and disconnects the electrical heat demand signal to the burner controller. The gas valves are then closed.

Ignition failure

If the flame is not established within the safety period the automatic ignition controller locks out. The safety period is about 25 seconds. Lock-out is indicated by the lamp in the RESET- button on the control panel. The unit has to be manually reset by pushing the reset button. If the flame is lost during normal run, the automatic ignition controller repeats the start sequence.

1.2.4Combustion products discharge safety device

The heater has been fitted with a combustion products discharge safety device. It is the function of the safety device to prevent flue gases from the water heater entering the room where the water heater has been placed, instead of passing through the flue to outside atmosphere. The gas supply is disconnected as soon as the device is activated by hot gases flowing over the sensor. After the cause of the re- entry of flue gases has been traced the device can be put back into

operation by pressing its reset button. If this failure occurs frequently, this indicates that the flue suffers from down draught conditions. It is recommended that a competent person carry out the necessary remedial action.

Important

The combustion products discharge safety device should never be put out of operation. Re- entry of flue gases to the building could be harmful and cause poisoning or death.

7