If it is a close coupled toilet you will need to turn off the water and disconect the cold feed , undo the nuts which hold the cistern to the pan and any screws from inside into the wall, lift offf the cistern and you will see a large usually plastic nut, if you undo this it will release the syphon , then put the new one in and put it all back together, have some ptfe tape handy for reconnecting the cold feed back to the toilet and dont cross thread it or overtighten it.
Steve, December 2004
