Here is my problem,
All of a sudden, the Wife complains of a cold shower, but if she jiggles the handle, it gets a little warm. It's a single handle model by American.
I thought maybe the problem was the electric water heater, but no, it pumps out perfectly heated water. I thought I would flush it anyway, just in case, and because I have been having a silt problem with my well, causing me to change filters more often. Not wanting to shut off water to the whole house, I just shut off the cold inlet supply to the heater and cracked the draincock to let it flow outside into my yard. After half an hour, I still had decent flow. That was when I realized that cold water was backflushing in from the hot outlet. Upon investigating, I can hear water rushing at the shower valve. I go out and buy a replacement cartridge, thinking that's the problem. This one doesn't have any fancy balls or ceramics, it's just the brass one with the holes and the angled groove around it. That improved the problem, to where showers are just about bearable. At the same time, I noticed my hot water at the kitchen runs hot, then cold, then lukewarm, then cold. My house has centralized plumbing, i.e. all the bathrooms and the kitchen are in the middle of the house so you don't get long plumbing runs. Even my well inlet comes up in the middle of the basement slab right in the center of things.
This handle is so old, the manufacturer's website doesn't have info on it, and they haven't deigned to answer my emails. Worse, I have no access to the valve itself. The shower side is a fiberglass shower enclosure, and the back side is in the main bathroom's linen closet, with no access panel. I know I need to just get in there and see what I got, I just wanted to see what others thought. I know newer handles have temperature mixing valves to prevent scalding, and I wonder if this one has that, and it has failed. I wonder if there are rebuild kits? Probably not, as you can't get just the valve, they want you to get EVERYTHING, valve, handle, showerhead, etc,etc,etc. I just can't think of any reason why water would be flowing from the cold to the hot side at this one valve. I posted this problem on justask.com, and was underwhelmed by the "plumber" who answered. He kept saying I had a broken dip tube in my heater, causing cold water to flow out before it was heated. After the first time he said that, I drained my heater, undid the inlet, and used a straightened coathanger to verify my tube was intact. It is. I even went so far as to remove the upper element and look inside with a flashlight to verify that, yes indeed, my tube was intact. He said it had to be my tube. When I asked how the tube would allow flow from the cold side at the valve, he ignored the question and reiterated his claim it was the tube.
Sorry for what turned into more of a rambling rant than anything else...