Close coupled is the most commonly found toilet design in the UK and Europe
There are several variants on the close coupled theme, but all have the cistern and pan directly bolted together.
The cistern is attached to the pan by means of two bolts which extend through holes in the base of the cistern and then through holes inn the back of the pan molding. The cistern is kept watertight with rubber washers which tighten and seal around the bolts and two nuts tighten under the pan to secure the cistern in place. The flush mechanism protrudes through a central hole in the cistern base and is again sealed with a rubber washer, and the flushing water is directed into a duct on top of the pan. A large rubber or foam washer, often referred to as a do-nut seals the joint.
 |
 |
 |
 |
How the cistern is attached
The pan can have an open back or a fully back to wall (fully shrouded) design, the latter being by far the neater option, but totally useless where the waste pipe has to exit the toilet to one side or the other. An open back pan must be used in these circumstances, the fully back to wall design is only suitable if the waste pipe exits straight through the wall behind the toilet, or into the floor.
Open back CCWC
The open back style toilet essential where the waste pipe comes out to one side of the pan, although it can be fitted perfectly with a straight out through the wall waste, or one turned down through the floor. There is , however, no disadvantage with an open back style other than the practicalities of cleaning and the aesthetics. The seats are much easier to tighten and adjust and it is possible to tighten plumbing joints if required after installation. Toilets designed in a period style will usually be open back if they are the close coupled variety.
Fully back to wall or Fully shrouded CCWC
A fully back to wall toilet is much easier to keep clean as the ceramic sides are smooth and close in all the pipework. The looks are much improved as no plumbing is visible, but more care is needed during fitting as the pipework is inaccessible after installation without removal of the complete unit. The seat mountings are fixed from the top, as it is impossible to reach the underside of the pan once it is installed. Also the connection to the soil (drainage) pipe must be made accurately to avoid leaks, as again this cannot be accessed after installation.
When viewed side on a fully back to wall toilet will sometimes appear bulky because of the larger expanse of ceramic material but in reality most will have a shorter projection from the wall than the older style toilet they are replacing.
Flushing
Many modern close coupled toilets in the UK and Europe employ a push button style flush, and often this has a full or half flush facility. The push button has become more popular recently, as regulations now require lower water consumption and the drop-valve type of mechanism used with push buttons gives a better flush with lower amounts of water.
Some toilets, particularly traditionally styled types, still use a lever flush with a siphon mechanism which uses larger amounts of water. The typical cistern of lever flush design holds around 8 liters of water, but modern cisterns will be set to hold only 6 liters and sometimes a little less.
Just to confuse the issue more recent lever flush toilets may be fitted with a cable action drop valve which will offer similar performance to a push button. It's worth checking out this detail before you buy. You can see more detail on cisterns flush systems here.
Rimless pans
The design of toilet pans has also improved to increase the efficiency of flushing, and a recent innovation is the rimless pan. This design removes the usual rim around the top edge of the toilet bowl making for much easier cleaning and greatly improve hygiene as the rim area, a real dirt and germ trap, is removed. The total surface around the top edge of the bowl is also fully glazed so is smooth and non-stick to stains and bacteria. The actual flush efficiency is unaffected due to the design of the pan and how flush water enters and is distributed around the bowl.
Some examples of close coupled toilets:
