A method and system for depositing a thin film on a substrate using a vapor deposition process is described. The processing system comprises a gas heating device for heating one or more constituents of a film forming composition. The gas heating device comprises one or more resistive heating elements configured to receive an electrical current from one or more power sources. Additionally, the gas heating device comprises a mounting structure configured to support the one or more resistive heating elements. Furthermore, the gas heating device comprises one or more static mounting devices coupled to the mounting structure and configured to fixedly couple the one or more resistive heating elements to the mounting structure, and one or more dynamic mounting devices coupled to the mounting structure and configured to automatically compensate for changes in a length of each of the one or more resistive heating elements.