As shown in the picture, I have green crust at the elbow of the copper exit pipe (I'm assuming its the exit pipe because its warm to the touch and encased in pipe insulation) coming out of the top of my water heater. It also drips a little. I know from reading other posts that I need to replace that elbow. I plan on replacing it with a Sharkbite corrugated stainless steel water heater connector.
My question is, do I need to drain the water heater before I cut the old copper pipe, or is it sufficient to just shut the water supply off to the water heater?
Also, is there any reason to shut off the gas supply to the water heater while I'm working on that pipe if I'm not sweating any joints?