Stacking (Tub/ Shower Valve)

plumbsharpWA

About 6 months ago, we installed a Delta posi-temp valve in a basement re-model. after we installed the trim, water would always come out of the tub spout and shower head (stacking). We used copper from the valve to both the shower head and tub spout. Water pressure was at an acceptable level. Tried a replacement spout, tried a new cartridge... Same problem. We then demo'd the wall from the other side, and replaced the valve altogether. Same problem still! Now we were mad! Long story short, we ended up running 3/4 Cu to the tub spout and it the problem stopped. Tub spout was HUGE, but it stopped! After installing over 200 valves, this was the only time it happened...Until now! Now it's happening to one of my co-workers, this time on a moentrol. We only use copper on the valves, and use pex (Viega) for the hot and cold supplies. Usually solder and adapter to a 8" piece of copper. Any ideas why it happened to me before, and why it might be happening now? He tried a new cartridge, and adjusted the the flow for hot and cold...

Ron The Plumber

You using slip on spots?

Dan_Watson

Amazing that this has come up twice today. I had the same problem with the exact same valve. What is the distance from valve to the spout and the shower head? Are they within the manufacturers specs? You are using copper from the valve to the spout and the head correct? An easy fix is to turn the supply valves down alittle at a time until the stacking stops . Also check out the post on the moen faucet from earlier tonight.