One thing I never do is, I never romance any of my equipment. My wife, certainly but my equipment, never. While I cannot get a close up of your welds, from the distance provided, it appears that you have a penetration issue and the welds appear gobbly. A welder is a welder, brand is inconsequential. Correct welding parameters are however and you are taking an unnecessary chance welding that close to your hot water heater with it's combustible gas supply, something I'd never do. In the shop I own, all welding, no matter what process is far removed from any foreign gas supply. Only takes one 'oops' to cause a major issue or end your existence, whatever the case may be.