Extract from the AS5601.1:2013 Australian Gas Regulations
6.2.10 Gas Appliance Support
Every gas appliance shall be supported on, or secured to a durable structure that is appropriate for the use and location of the gas appliance. The supports shall maintain the gas appliance in a plumb or level position and the means of securing the gas appliance to its support shall be of suitable materials and strength for the purpose. Gas appliances shall not be supported by gas pipework unless the pipework has been designed for that purpose. The gas appliance shall be supported and placed so that the weight of the gas appliance will not cause deformation of any part of the building structure and wherever possible shall be located directly over or close to a load-bearing member.