GTA was engaged by our insurance coordinator to replace a gas hot water heater in the midst of a flood due to the very cold winter we had last year. They are, in fact, not licensed to install gas appliances and have a sub they use. The sub installed a gas water heater which did not comply with code guidelines, and we had to have it replaced.
This whole affair has cost us a lot of money. I do not recommend GTA for any gas related issues.