Soil pipe connection for the toilet
When buying a new pan, you will also need to buy a suitable connection piece for the soil outlet. They are push fit connections with multiple fins of rubber to make a watertight seal. There are several different shapes and angles available - angled, straight, offset and radiused. Choice will depend on the existing pipe and its position in relation to the pan, as well as the size of the pipe itself. Be sure to take a note of the internal diameter of the soil pipe and the external diameter of the pan outlet. Also sketch out the measurements of the distance and offset of the two pieces.
Push the connector piece onto the pan outlet and move the pan into position with the connector going inside the soil pipe. Don’t forget to take the rags used earlier out of the soil pipe. Mark the fixing point of the pan on the floor. Remove the pan and drill and plug these if the floor is of a solid type. For wooden floors, simply drill a small diameter pilot hole for the screws. Remember to check there are no hidden pipes or cables running under the drill holes. Do not fix the pan yet, but line it up again ready.
Assembling the cistern
Now, assemble the cistern with all its internal workings following the manufacturer's instructions and connect it to the pan. This may be via a flush pipe, or the cistern may sit directly onto the pan. Look carefully at the assembly instructions since the correct mounting of all parts is important and may vary from manufacturer to manufacturer.
Fixing the toilet cistern to the wall
Ensuring that it is level, mark the fixing points for the cistern, lift it out of the way and drill and plug the wall. Reposition the cistern and fix. Note that you must use brass screws since steel ones will corrode in the vicinity of moisture. Generally, the screws are mounted through small rubber gaskets to prevent damage. Be careful not to overtighten the screws as the ceramic cistern will crack very easily. If needs be, use some offcuts of small diameter plastic pipe to pack the cistern out from the wall.
If you are planning to tile the wall later, put in a couple of temporary packing pieces of wood equivalent to the thickness of the tiles.