jimbo596
Your household pressure may be too high. The mixer valve has direct openings to the spout and shower; only the pressure drop due to flow to the tub keeps water out of shoer head; but if incoming pressure is high, the water will rise to the shower.
Many newer mixers have a restricter in the shower outlet, but an older one may not.
Finding a spout which allows greater flow may help, especially if present spout is partially blocked by mineral buildup.
