Hi Bill: I'm glad you liked the concept but am sorry about the incident with the gas valve. Was a hot water tap open at the time? Regardless, with an Aqua-Star, it is almost a physical impossibility for the gas valve to open while the unit is switched to PILOT, even with tap open. There is a tiny electro-magnet in the pilot circuit which prevents this very thing. The Aqua-Star has been around in (almost) its' present form, for around 65 years. I have sold,installed and serviced these heaters for 9 years and have NEVER seen this happen. Conclusion: it wasn't an Aqua-Star. Controlled Energy Corp' has a free tech service dep't which is second to none in the industry, and would have told the maint' man what the problem was in less than a minute. If anyone needs any info on any of CECs' products, please contact me at 800 851 9891 or E-mail email@example.com Regards Brian Wood the Waterguyser. Happy New Year.