When we replaced our existing gas heater it was 30 years old and Stephen from HiTech Gas services had kept it going for the last 5/6 years of it's life. He and Roger did a great job keeping it going, but eventually the unit failed and parts to fix were not available.
Stephen helped us research new options and recommended a couple of potential installers. We met with John Montgomery , he impressed us so much with his attention to detail and " perfection" approach"that he got the job.
Having read other reviews herein I concur with both K Duffy and A Pitman that John and Stephen were the best people for the purchase and installation.
Both these gentleman come highly recommended if you require a professional and competent approach to your installation.

Ted - Wahroonga