New ceramic tap gland is stiff

[Simone]

Hi, fitted some new ceramic 1/4 turn tap glands as the hot one was leaking but the cold tap now feels stiff and jerky, the hot one is fine nice and smooth but the cold one isn’t, it’s fine when it’s out of the tap you can turn it easily but once fitted in the tap it goes back to feeling stiff, is it something to do with it being mains fed unlike the hot tap, any ideas.?

 

[Chuck]

The ceramic discs maybe damaged/rough but this is not likely if the operation is silk-smooth when not installed. More likely, the body is slightly too long so when it's installed in the tap the seal is compressed too much, which pushes the ceramic discs together too firmly. There may be a fibre washer that seals the flange at the top of the thread to the tap body; if this is missing or too thin it will have the same effect.