I have installed AO Smith, GE, Rheem, Ruud, American, and Bradford-White heaters and have NEVER had problems with any of them. Therefore, I have no basis to NOT recommend any of them based on my personal experience. But if there is an existing water heater, and a new one replaces it, without ANY modifications to the environment, I cannot see where any subsequent problems could be due to the installation. If the installation discloses environmental problems, then these would have to be analyzed and remedied, but if they are the cause of your symptoms, they will still be there with the new heater. The combustion air intakes just control the burner's proper operation, and the FVIR is an emergency feature that the average user will NEVER need, unless he likes to store gasoline cans next to his water heater.