So I disassembled my water heater pipeline and tested it. Cold water in, hot water tank (there's a valve for testing on the tank), and hot water out. All three have full pressure.
Just down the line, the washing machine has 70% pressure on hot water versus cold water. Kitchen is 70% or so, and bathroom upstairs is VERY slow, maybe 30%.
Coming off the water tank
This is where that pipe goes. Branch off to washing machine follows down the line. Branch off to kitchen follows after a 90 bend, which the cold water pipe also has.
This is down the line. The hot water line has 5 more bends, cold has 2 more. This is after the kitchen, before the bathroom.
- Run the flexible hose into a 1 inch connector that goes to 2 inch pipe
- Run the 2 inch pipe out past the cold water line, connect to main hot water line
I'm hoping the 2 inch pipe will provide less resistance around three 90 degree bends than 1 inch pipe. If I run the pipe sloping down, I can make that two 90 degree bends. Alternately, I could make it a complete run of flex pipe?
Getting the hot water line on the opposite side will eliminate all that stupid crap in the third image. That's 2 bends in the cold water line and 4 in the hot water line.