I have an older shower with a 3 valve handle system. I can have the hot handle fully opened and when I barely crack the cold handle the hot water quickly goes to all cold as if its not mixing correctly.

I have removed all three valves and verified there is no clogs in the piping, i have recently replaced the seats that screw onto the main body and also replaced all three of the handles, and the problem still is there

Any ideas on what could be causing the water temp to not be mixing correctly?

what material are you water pipes made of?

What does Older mean? 1930's ? What brand?

Best Wishes

Compression or washerless?

The pipes are copper and the house was built in 1964 and it uses the rubber washers that compress to the bibs that screw into the main water valve



Edited 1 times.

No, because you are describing either a volume or pressure imbalance, and that could be caused by the building's piping system, not the tub valve. WE would have to be there to do our own tests to see which is the problem and how to cure it, assuming a cure is economically possible.