My faucet has 1/2" IPS copper supply tubes (you can see the type from http://www.americanmaintenance.net/...lta/520-522.pdf
). I don't know what IPS mean? But the internal diameter of the compression nut is 1/2". The cropper line from the hot/cold water supply come with a 1/2" compression nut, which exactly fits the seat in the copper line from the faucet. There's also a ring in between.
The problem is: my old faucet has exactly the same copper tail piece as the new one. When I took it apart, I saw the fitting (putty I think) in the nut. I left the fitting there and connected one tail piece with the hot water supply line. Everything works fine: there's no leak. And also I can feel that the connect is solid since I cannot move the copper supply tube when I shake or pull it. However, I met trouble when connecting the other copper tail piece with the cold water supply line. The problem is I removed the left fitting in the nut: I thought it's old so I just put the new putty in. But no matter how hard I tried, I just couldn't make the copper cold water supply line connected to the tail piece: there's a gap inside? My guess is when I tighten the nut, the ring will be pressed into the seat, causing it to compress against the tail piece and the nut. But it didn't work.
How come I could connect one (the hot water one) but couldn't connect the other one? Does the ring defect? I heard that the ring might defect and cause such problem. Do you have any expererience.
I am really new to this. It's my first condo and I just spent a lot of time on it and bought a lot of tools to fix this. At the beginning I had confidence to fix it, but now I'm lossing patient. Don't know wheater I will end up with asking for a plumber to come. :P