A quick google search will let you know that the ideal valve height is 28 inches or 2 feet 4 inches for a standard bathtub shower.
In the case of a shower stall, the shower valve should ideally be installed at the height of 48 inches or 4 feet. The faucet should be installed at the same height as the valve, and at the same time, it should be equidistant from the shower valve.
The most important thing that must be kept in mind while installing a shower valve that is it should be positioned in such a way that it is easy to reach and get a hold of every member of the household and that it is not placed in such a manner that the valve hurts no one, especially the kids in the house.
You might want to get the shower valve installation in the first attempt itself because it takes a lot of effort and time. The local building code plays an important role in determining the height of your shower valve as every resident of the building has no other option but to abide by the code.
Also, you have a check whether there are any regulations that govern the installation of shower, faucets, etcetera in your building. You will have to follow them before you begin planning for the installation process.
While installing the shower head, you will have to make sure that the tallest person in the house does not have any problem using the shower and that the showerhead is installed a few inches above their head so that they do not dash with it.
At the same time, you have to make sure that the showerhead is not way beyond reach for the shortest person in the house; everyone in use must be comfortable with the height of the showerhead.
There is no set or standard height for a shower valve mentioned anywhere; as discussed earlier in this, for a bathtub, the shower valve is ideally installed between 28-36 inches, and for a normal shower, the valve is installed at the height of 48 inches from the floor.
The user must consult with a plumber or a builder before installing the shower valve and take the comfort of all the members of the house into consideration.
Most of the time, people make the mistake of not planning before they install their shower valve, and hence they end up installing the valve at a height that is uncomfortable to reach.
No one wants to go through the process of installation again and again as it is quite tedious in nature. Though installing a shower valve might seem like a complex task and there are chances that the installation might go wrong.
The user must move ahead with confidence, plan the entire process, and take all the necessary measurements so that the errors are as minimized as much as possible.