All gas burning appliances shall be of an approved vented type. Gas heaters shall be connected to a flue or vent not less in size than the vent collar of the appliance. The flue or vent shall be of approved incombustible materials and shall be carried to the outer air. Vent outlets shall terminate with an approved vent cap not less than twelve inches above the highest point of the trailer or roof of any building, cabana or ramada. Every gas burning appliance shall be connected to the gas supply piping with approved metal piping and the gas supply outlet shall be equipped with a shut-off valve and each appliance shall be equipped with approved automatic shut-off devices which will shut off the gas supply to the main burner or burners and pilot in the event of pilot failure. (Prior code § 17.48.010.)