When i turn on bath water it runs also from the shower if i pull lever up for just shower than just shower runs

I had the same problem. My building manager showed me that you have to yank the circular portion at the end the of spout where the water comes out downward and the water will be diverted to the showerhead.

If you pull the silver knob on the tub spout up, the diverter located located inside will redirect water up to the shower head and when lowered it will return the water to the tub spout. It sounds as thought the diverter is not working properly. Hope this helps..

mite have intergral stops behind escution plate (the big round cover plate with 2 screws) that needs to be turned to the on position..

replace gaskets, and hot & cold water stems inside of manifold (turn off water first).

Is there a button on the tub filler? How about the spout on the tub, does it lift up? If there is not a tub spout then it should be shower only, if it has a tub spout it has to have a lifter of some sort, the foto I found showed the little button lifter. Hope this helps.

if it is standard shower where you pull the knob up when water is running. the pull knob lifts a flap to shut off water to bottom faucet it proably has some buildup on the flap clean well with some clr or other calcium cleaner like it so the flap gets a clean seal on downspout

Try draining the system and apply air pressure (min 30psi) to each faucet. Open other hot water faucets to allow pressure to vent. Next try draining and cleaning the hot water tank.

Sounds like it was installed upside down or the cartridge is installed improperly

Probably has water deposit minerals build up on it. Push and or pull with pliers until freely moves,soak in Lime away solvent ,toothbrush on.

Verify the height from the shower valve to the Shower head, the instructions specify the correct distance if it is too short the pressure could be getting up to the shower head.

Perhaps the water pressure it too high at the valve not allowing all the water down the faucet outlet, there are set screws on the sides of the shower valve to adjust the water allowed in the mixing chamber.

Something is restricting the water flow to the faucet, creating enough pressure to send some of the ater supply up to the shower.

I hope some of these ideas help