My old State 40 gallon gas hot water heater started banging around recently, so I flushed it out...long story short, it was 15 years old and I replaced it, even though it worked great. I didn't want to come home to a mess. It was banging loud enough that I could hear it on the first floor from the basement. I bought a 40 gallon GE (Rheem) from Home Depot. I have a mix of galvanized/plastic/copper plumbing in my basement, and my basement is about 6 feet tall on a good day. I ended up hooking up the new heater with stainless steel flex pipes, and I had to loop the hot tube and install the cold in a 180 degree bend. Neither is kinked. It doesn't look super professional, but it fits. After my wife complained of a shower that got cold after 15 minutes, I turned the thermostat from 120 to 130, then to 140, and finally to 150. It's better, but she's still getting cold at the end. I called GE, and they sent out a new sensor/thermostat, which I installed. I put the thermostat on 140 after I was done. My shower on the first floor seemed to have plenty of hot water, but I did have to turn the cold mix down as I took a shower. If I turn the cold off, it's scalding hot even after 10 minutes. In her shower upstairs, which has never been as hot as mine, I now can barely turn the cold mix on to maintain a decent temperature. This was not a problem before the new hot water heater. So--I'm wondering what I may have done wrong, or if there's something wrong with the heater itself. Any input is appreciated...Thanks!