A timely reminder to follow the lighting instructions.

Building and Energy recently investigated an incident that resulted in a gasfitter being admitted to hospital after sustaining flash fire burn injuries to the face and eyes while attempting to relight a gas storage water heater.

This incident occurred while the gasfitter was attending a service call when the property owner advised the gasfitter they were having difficulty relighting the gas storage water heater.

Building and Energy’s investigation of this and other similar relighting incidents, found that these incidents could have been avoided if the manufacturer’s lighting procedure had been followed.

The investigations also identified that some of the older gas storage water heaters that were not serviced as required by the manufacturer’s instructions had corrosion issues. The corrosion allows the water/moisture to leak from the thermostat flange into the gas control valve. In some instances, it was found that the moisture ingress caused deposits within the gas control valve that subsequently impacted the operation of the gas valve and resulted in the main burner gas being supplied during the ignition/pilot proving period. This means if ignited it may result in a large flame/explosion that may exit the chamber, subsequently injuring the person that is lighting the water heater.

Building and Energy recommendations to gas fitters are:

• Prior to undertaking any gasfitting work, the gas installation should be pressure tested to ensure it is gas tight with all appliance isolation valves open.
• The manufacturer instructions should be followed when lighting all gas appliances (for gas storage water heaters they are normally printed on the inside of the burner cover). Do not place your face below the gas valve or in front of the combustion chamber when attempting to light it.
• In situations when the consumer has reported difficultly in relighting gas storage water heaters or the appliance is several years old, undertake the following:
  • In all instances, follow the manufactures instructions when undertaking any maintenance on a gas appliance.
  • Contact the manufacturer for their recommendations if there are signs of water leakage around the thermostat flange (commonly known as the dry pocket), behind the gas valve and also within the combustion area.
  • Do not introduce a source of ignition into the combustion chamber until you have proven the gas control valve is operating correctly. Refer to the manufacturer for instructions for testing the operation of the control valve.

Image 1 - Gas storage water heater corrosion

Image 2 - Gas storage water heater corrosion