Replacing your WC need not be a frightening prospect provided you follow a few basic rules. It also gives you the opportunity to install a quieter and more efficient piece of equipment.
There are several reasons why you may wish to remove and replace your WC suite. The existing pan may be cracked, in which case replacement must not be delayed, and no attempt should be made to repair it. Or the porcelain may be crazed making it unsightly, and difficult to keep clean. Most likely, however, the reason will be that your existing WC is simply old fashioned and due for replacement as part of an overall improvement plan.
Pan or cistern?
If it’s just the pan you find fault with then that’s all you need to replace. Colors for sanitary ware, as WCs are usually called by the manufacturers, are fairly standardized, and you should have no difficulty in obtaining a pàq to match the existing cistern.
lf, on the other hand, you want to convert an old-fashioned lavatory suite with a high- level cistern, it may be possible to replace only the flushing cistern and flush pipe (or ‘flush bend’ as it is often called) with a low level one, while keeping the existing pan.
However, in order to accommodate the flushing cistern, the pans of low level suites are usually positioned 25 to 50mm (1 to 2in) further from the wall behind the suite than are those of high level ones. If you overlook this point you are likely to find that the seat and cover of the pan cannot be raised properly when the new cistern is fitted.
In recent years manufacturers have developed slim-line flushing cisterns or ‘flush panels’ only about 115mm (41/4iri) deep. These can, in most cases, be used to convert a WC from high level to low level operation without moving the pan. With such a cistern the flushing inlet to the pan can be as little as 130mm (51/4in) from the wall behind, instead of the 200 to 230 (8 to gin) required by an ordinary low level cistern. To make room for the full 9 litres (2 gal) of water needed for an adequate flush, these slimline cisterns are rather wider from side to side than conventional ones. So make sure that there is sufficient unobstructed width of wall behind the suite to accommodate it.
Close-coupled lavatory suites, in which the pan and cistern form one unit without even the short flush bend of a low level cistern, are neater in appearance than the other kinds. They are particularly silent and effective where they are flushed and cleansed by siphonic action, as distinct from the ‘wash down’ action in which flushing simply releases the full contents of the cistern into the pan, and the weight of water carries away its contents. They also provide a larger water surface area than older pans, an important factor in maintaining the cleanliness of the pan.
There are two kinds of siphonic suite, single-trap and double-trap. The single-trap pattern is the simpler and cheaper. The outlet is first constricted and then widened to connect to the branch drain or soil pipe.
When the suite is flushed, water completely fills the restricted section of the outlet and passes on, taking air with it, to create a partial vacuum. Atmospheric pressure then pushes the contents of the pan into the drain. The siphonic action is broken, often with a gurgle, as air passes under the bend of the trap.
With a double-trap siphonic suite, a specially designed air pipe or ‘pressure reducer’ connects the air space between the two traps to the channel through which the flushing water passes. As this water flows past the pressure reducer it sucks up air from the space between the two traps, in the same way that the wind passing over the top of a chimney sucks up air from a room below.
It’s this that creates the partial vacuum on which siphonic action depends. Where a double-trap siphonic suite is working properly, you’ll see the water level in the pan fall before the flush’ water flows in. Although more expensive than other kinds, these suites are valuable where, as in an entrance lobby cloakroom for instance, silent operation is a prime consideration.
Just as low level WC suites normally project further from the wall behind them than high level ones, close-coupled suites project further than either. Don’t forget this when considering the provision of such a suite in a small bathroom or cloakroom. You may have to change the position of the washbasin and this, in turn, could obstruct the door.