A contractor installed a new shower valve. The old valve was a Moen Legend circa 1994, worked fine. The new valve is a Glacier Bay ( long story…he didn’t ask before doing it) single handle pressure balancing valve. Now when the handle is turned to an intermediate position between Cold/Hot the output pulses continuously. Notes: 1) Supplies and output are 1/2″ PEX; Whole house is PEX w/manifold. 2) Shower valve is at the opposite end of shower from shower head and PEX goes through the attic. 3) At the fixture inputs he changed the inputs to CPVC and then the CPVC connects to the Shark fittings to the 1/2″ PEX 4) Not sure if the valve is upside-down or the cold/hot are reversed but the shower output is from the bottom of the valve.
Not choice but to tear out the tile to get it out and replace it. But I would like to know what is causing the problem.