Wrap plumber’s tape (PTFE tape) around the threads of the copper pipe ends—five laps, clockwise. Then slide the new stopcock into place, with the handle lined up so it points forward (or whatever your soul desires). Tighten the compression nuts with your spanner—finger-tight first, then a quarter turn. Do not overtighten or you’ll crack the fitting and have a sad, wet basement. This is not a test of strength; it’s a test of finesse. You’re a ballet dancer, not a blacksmith.
Check the handle moves freely. If it doesn’t, you’ve installed it upside down, like a shirt on a drunk person. Fix it now.
How to Fix a Leaking Stopcock | Step-by-Step | Checkatrade
