Installing a Kohler Rite-Temp pressure balance bath & shower valve, K-304
Rough in instructions from Kohler with some added tips.
Most plumbers will remove the cartridge, and solder pipe to the valve body first, and then reassemble the valve. The valve comes with the option to thread on a "female adapter", or to insert copper pipe into the brass body of the valve. I prefer to solder copper pipe to the valve.
two, The pipe to the tub spout needs to be full size. No PEX here. PEX is undersized for a tub spout and will force water up toward the shower head. Either copper or threaded pipe like galvanized or brass. I use either copper or brass. Galvanized will rust and the first time you open the faucet in the morning, you will get some rusty water.
three, if you have a back to back installation like below, you can reverse the valve without making the pipes cross over.