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. Colours for sanitary-ware, as Wcs are usually called by the manufacturers, are fairly standardised, and you should have no difficulty in obtaining a pan to match the existing cistern.

If, 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.

Slim-line cisterns

In recent years manufacturers have developed slim-line flushing cisterns or ‘flush panels’ only about 115mm (41/iin) 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/iin) from the wall behind, instead of the 200 to 230 (8 to 9in) 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.

Siphonic suites

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 particuidily silent and effective where they are fluohed 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.

Pan fixings

Moving an existing WC pan isn’t always easy. It’s likely to depend largely upon whether it is installed upstairs or on the ground floor. Upstairs Wcs usually have a P-trap outlet, which is almost horizontal and is connected to a branch soil pipe by means of a putty or mortar joint. This can easily be broken with a club hammer and cold chisel once you have disconnected the pan from the floor.

Downstairs Wcs usually have their bases firmly cemented to a solid floor and usually have an S-trap outlet which is vertical. This connects via a cement joint to an earthenware drain socket protruding above floor level. To remove such a pan it’s necessary to break the outlet. Use a cold chisel to detach the front part of the pan from the floor, then use a cold chisel and hammer again to clear the pan outlet and the joining material from the drain socket.

Nowadays it is usual to connect both ground floor and upstairs Wcs to the soil pipe using a flexible joint, usually a patent plastic push-fit joint with a spigot that is inserted into the drain and a ‘finned’ socket that fits over the WC pan outlet.

Such patent joins are nowadays manu-factured in a range that covers virtually any WC installation. Not only are they easy to use but they help reduce the noise of a flushing lavatory. It’s not considered to be good practice today to cement the base of a WC to a solid floor, as the setting of the cement can create stresses resulting in a cracked pan. It is best to remove every trace of cement from the floor and, having achieved a dead-level base, to secure the WC pan with screws driven into plugs pushed into holes drilled in the floor.

How to start

After you have turned off the water supply and flushed the cistern to empty it, the next step is to disconnect the cistern’s water supply, overflow and outlet pipes. So begin by unscrewing the cap-nut connecting the water-supply pipe to the cistern’s ball-valve inlet. Then undo the back-nut retaining the cistern’s overflow or warning pipe. Finally undo the large nut which secures the threaded outlet of the cistern to the flush pipe. It should now be possible to lift the old cistern off its supporting bracket or brackets.

If the WC suite is a very old one and screwed to a timber floor, unscrew and remove the pan’s fixing screws. Then, taking the pan in both hands, pull it from side to side and away from the wall. If the connection to the soil pipe is made with a mastic or putty joint, the pan outlet should come easily out of its socket (which will have to be cleaned of all jointing material before the new unit is fitted). If a rigid cement joint has been used then there’s usually no alternative but to use a bit of force. This means deliberately breaking the pan outlet, just behind the trap and above the drain socket, with a club hammer. You can then prise the front part of the pan away from the floor using a cold chisel and hammer. This will separate the pan outlet from the drain. At this point it’s a good idea to stuff a bundle of rags or screwed-up newspaper into the drain socket to prevent any debris getting into the soil pipe. Next attack the socket to remove the remains of the pan’s outlet. For this, use a small cold chisel and hammer but do it carefully to avoid damaging the drain socket itself – this will be used again. It’s best to keep the point of the chisel pointing towards the centre of the pipe. Try to break it right down to the shoulder of the socket at one point and the will then come out fairly easily. Repeat the chipping process to remove all the old jointing material. Remove the bundle of rags or newspaper with the fragments of pipe and jointing material. Then with your cold chisel, remove every trace of the cement base that secured the old pan to the floor.

Installing the new pan

Don’t set the pan on a cement base – just use screws and plugs to fix it to the floor. But first you’ve got to get the connection to the drain socket right. Start by positioning the patent push-fit joint in the drain socket. Then offer up the new pan to the patent push-fit socket and move the pan around until it fits snugly. To fix the pan, mark the screw positions on the floor by tapping a nail through the screw-holes, and draw round the base on the floor so that you can replace it in exactly the same position. Drill holes in the floor at the points marked and finally fit the screws. If it’s a solid floor, of course, it’s essential to use plastic or fibre plugs in the screw holes.

For fixing the pan, it’s advisable to use brass non-corroding screws with a lead washer slipped over each one so you won’t crack the pan as you tighten the screws. Screw the pan down, checking that it is exactly horizontal with the aid of a spirit level laid across the top of the bowl. If it is not dead-level, pack the lower side with thin wood or plastic strips. The latter are more suitable because thin wood rots too easily. Finally check that the outlet of the pan is firmly pushed into the connector and that you’ve followed any specific fitting instructions from the manufacturer.

Fitting the cistern

Fix the new cistern to the wall at the level above the pan recommended by the manufacturer. In the case of a separate cistern, secure the upper end of the flush pipe to the cistern, usually by means of a large nut, and the lower end to the pan’s flushing horn with a rubber cone connector. With a close-coupled suite, follow the manufacturer’s instructions. You will now quite likely have to extend or cut back the water supply pipe to connect it to the new cistern. Complete the job by cutting and fitting a new overflow.


There are two sorts of flushing mechanism the bell type in well-bottom cisterns and the piston type found otherwise. The latter is by far the more popular today.


You’ll find you have to assemble the mechanism which is bagged up inside the new cistern. Lay out the components (A) and check them against the enclosed instruction leaflet before assembling them correctly (B).

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