I want to keep it simple with the fewest fittings and joints. However, I want to add a ball valve at the 3/4" tee so I can isolate that section of line without draining the tank. I want to stick with PEX line, but I was thinking of using shark bite type fittings.
I have zero plumbing experience and not a lot of common sense. I had a licensed plumber plumb my house, and the return line in the pic is his handy work.
I had to remove the water heater so that I could have a concrete floor installed. I ran into a problem when I went to reinstall that section of return line. As I was tightening the ball valve onto the nipple it was loosening up from the PEX fitting. I had a similar problem connecting to the nipple at the 3/4" tee.
I have slow leaks on both ends.
I've done some research and scoured Home Depot dot com. It seems like this should be as easy as connecting a garden hose to two faucets.