Just installed a Grohe Eurosmart 19-913 tub & shower control.
Whenever we use the tub filler, the shower head is on at half volume.
Pulled out the mixing cartridge and reset it, but that has little to do with volume control and didn't help.
The shower is controlled by a push-down knob on the tub filler. When we use the shower head, the tub filler is shut off and everything functions fine.
But when we use the tub filler, the shower head is running continuously at half volume.