Hot water coming out at cold water side of Positemp valve
Hi,
Plumbers recently changed the pipes and installed new tub/shower valves in our building. But since they changed the shower valve (Moen single-handle Positemp that turns 270 degreees but doesn't pull out), hot water comes out when you first turn the handle counterclockwise. It gets cooler as it goes from hot at the just-open 6 o'clock position to 3 o'clock (where, at maximum coldness, it is now somewhere in the vicinity of lukewarm/tepid/cool, but definitely not COLD). It then gets hotter again as you turn counterclockwise from 3 o'clock back to 9 o'clock, where it is fully hot. So the water goes hot -> lukewarm/cool -> hot, but there is no unadulterated cold water ever, so clearly there is a crossover problem. But where is it most likely occurring? Is simply changing the cartridge likely to fix this (as Moen customer support have suggested)? Or is there something else that is more likely to be causing this problem?
Looking forward to hearing from any of you have encountered this problem before!