When I take a shower, I have hot water for the first 3-4 minutes. Then I have to completely turn off the cold water to make it through the rest of the shower. I opened the upper and lower access doors and felt the tank. It seemed that the bottom was cooler than the top, so I replaced the lower element. But there is no change to what I am getting. Any thoughts on what I should have done?

On the small copper cold water pipe going into the top of the heater, there is a "big" shut-off valve with a round handle. Below it, and going towards the top of the heater are two small valves, in-line, that are clamped onto the pipe, and they have a small (about 2mm in dia, 2" long) T-bar handle on them. I woke up this morning to find water spurting out one of these small valves. It wasn't leaking from the valve. The water was coming out from the outlet from the valve. I turned the valve off and the water stopped. 1. What is this valve for? 2. Why was water coming out of it even though I never opened the valve? 3. Naturally, it's a good thing that I shut off the valve to keep water from coming out, but because it opened (somehow) in the first place, and now I shut it off, is there anything to worry about? Thanks, Dan