I just bought my house and noticed there is a problem in the bathroom tub faucet and that is: the valve starts from the cold toward hot and as it goes toward the hot the water pressure increases and by the way the way it is made I do not have any access behind the wall to check how it is made. Is there any way I can fix this and have control over both water temperature's pressure?
Delta makes a line of shower valves (Monitor 17 series) that has separate Temperature and Volume controls in a single hole package. It approximates a thermostatic valve, which is a much more expensive valve.
The little arm at 2 o'clock is the temperature setting, and the larger one at 4 o'clock is the volume.
It would be necessary to replace both the valve body and the valve trim to use this solution.