Installing The W.C. Suite

From many points of view the w.c. suite is the most important and critical item of the householder’s plumbing installation. A bad choice of suite can lead to embarrassment. Faulty installation can produce a positive risk to health.

It is not always realised that there are three different kinds of w.c. suite in common use, and they they depend upon quite different principles for their cleaning and recharging with water after use.

Commonest is the straightforward wash-down suite. This depends for its flushing and cleansing action solely upon the weight and momentum of the two gallons of water released when the flushing cistern is discharged. Wash-down w.c. pans may be used in both high level and low level suites. For efficient cleansing-particularly with low level suites-the following conditions are essential. (a) The float arm of the ball-valve should be adjusted so that the water level of the cistern when full is at the mark indicated on the inside of the cistern wall, usually about V6in below the overflow of warning outlet. (b) The flush pipe should be of the diameter and length recommended by the manufacturer. It is best when installing a low level suite to buy pan, flush bend and cistern as one unit from the supplier. (c) The flush pipe must connect absolutely squarely to the flushing horn of the w.c. pan and no jointing material must be permitted to obstruct the flush inlet. The old-fashioned way of connecting a flush pipe to a w.c. pan was with a ‘rag and putty joint’. Apart from the fact that a connection of this kind is thoroughly unhygienic, the nature of the joint frequently resulted in putty obstructing the flush. Some modern w.c. pans are provided with a patent ‘O’ ring connector for the flush pipe. The alternative is to use a push-on rubber cone connector. (d) There must be no obstruction-from putty, flakes of rust, hard water scale or other debris-within either side of the flushing rim. This can be checked with a mirror or by feeling with the fingers. (e) The pan must be set dead level. This should be checked with a spirit level. If necessary, the pan can be made level by packing slivers of wood, or pieces of linoleum, under the lower side. (f) The pan outlet must be set squarely into the socket of the branch drain or soil-pipe and, when fitting, care must be taken to ensure that any cement or mastic jointing material is not extruded into the connection between pan and socket to reduce its effective diameter.

When a wash-down suite is properly installed flushing water should flow evenly from each side of the flushing rim, the flushing water should meet in the middle of the front of the pan and there should be no marked rise in water level and no ‘whirl-pool effect’ as the pan empties.

Wash-down suites are suitable for most domestic, industrial and commercial purposes. Where a more positive cleansing action is required or where the position of the w.c. suite makes silent, unobtrusive action a prime consideration, then one or other of the two kinds of siphonic w.c. suite should be installed. These depend, to a greater or less extent, upon the weight of the atmosphere to push out the contents of the pan by siphonic action. Since they do not depend upon the weight and momentum of the flushing water for their cleansing effect they permit the use of ‘close coupled’ w.c. suites in which the flushing cistern and the pan comprise one unit without even the short ‘flush bend’ required for a low level wash-down suite. This markedly reduces the noise of flushing.

The simpler ‘single trap’ siphonic suite depends for its effectiveness upon the design of the outlet of the pan. Immediately behind the trap the outlet is first constricted and then widened. When the flush is operated, water overflowing from the trap completely fills the constricted section of the outlet and then enters the wider section carrying air with it. This creates the partial vacuum upon which siphonic action depends and the contents of the pan are pushed out by atmospheric pressure.

When a siphonic closet of this type is flushed water will first rise slightly in the pan. The contents will then be quite forcibly ejected. The siphonic action will cease when water level within the pan falls to a level at which air can pass into the trap. Single trap siphonic suites are rather prone to accidental blockage-usually as a result of misuse. Although they flush silently the passage of air into the trap to break the siphon can produce a somewhat noisy gurgle.

A more positively silent action is provided by the double-trap siphonic w.c. suite. A suite of this kind is, in my opinion, always to be preferred where silent, unobtrusive and efficient action is of greater importance than the initial cost of installation.

As its name implies a double trap siphonic suite has two traps built into the outlet. The air space between the two traps is connected to the flushing inlet by means of a short pipe or ‘pressure reducing device’. When the flush is operated, water flowing over this pressure reducing device aspirates air from the air space in the same way that the wind, blowing across a chimney stack, will aspirate air up the flue from the room below. This action creates a partial vacuum in the space between the two traps and the pressure of the atmospheric pushes out the contents of the pan. Where a double-trap siphonic suite has been properly installed the water level in the pan can be seen to fall before flushing water actually reaches the pan. Having set the siphonic action into operation the main purpose of the flushing water is merely to recharge the pan.

Apart from its silent action a further advantage of this kind of w.c. suite is the fact that the large water area that its design makes possible, reduces the risk of the sides of the pan becoming fouled. Unlike most sanitary appliances the trap of the w.c. suite is built in to the fitting itself. Ground floor w.c.s usually have an ‘S’ trap with an outlet connected directly to a branch underground drain. Upstairs w.c.s are usually connected to a branch soil pipe and have a ‘P’ trap with a horizontal outlet. A variety of angled ‘P’ outlets are available for installation in difficult situations.

It is usual nowadays to connect both ground floor and upstairs w.c.s to the drain or soil pipe by means of some kind of flexible joint. This may be a patent push-on plastic joint such as the ‘multikwik’ or may be made in situ using a non-setting mastic filler such as ‘plumber’s mait’.

In the past ground floor w.c.s were always connected to the stoneware drain socket by means of a cement and sand joint using two parts of cement to one of sand. A grommet of tarred hemp, or a wad of dampened newspaper, was first caulked into the space between pan outlet and socket to prevent jointing material entering the drain and causing a partial obstruction. Upstairs w.c.s were sometimes connected to iron branch soil pipe sockets in the same way. This was never a satisfactory arrangement however. Vibration or movement of the wooden floor to which the w.c. pan was screwed inevitably resulted in a cracked and leaking joint.

Remedying a leak in the joint between w.c. outlet and drain or soil-pipe socket is a common maintenance job. A radical remedy is, of course, to disconnect the w.c. pan and to replace the existing joint with a push-on plastic one. This may not be convenient or even possible. An alternative is to rake out the existing jointing material and to bind two or three turns of a waterproofing building tape such as ‘sylglas’ round the w.c. outlet, caulking it down hard into the socket of the soil pipe or drain. Fill in the space between outlet and socket with a non-setting mastic such as ‘plumber’s mait’ and complete the joint with another couple of turns of waterproofing tape.

When fitting a new w.c. pan onto a solid floor it should nor—as was usual in the past—be set in a bed of sand and cement mix. It has been established that the setting of the cement can produce damaging stresses. The pan should be screwed down with non-corroding screws. Place the pan in position. Mark through the screw holes with a ball-point refill. Remove the pan, drill the floor and plug. In order to make sure that the pan is placed in exactly the correct position over the plugs it is a good idea to insert short pieces of wire into the plugs. The pan can then be lowered over these pieces of wire which are removed before the screws are inserted. Slip a lead washer over each screw before insertion to avoid the risk of damaging the ceramic surface of the w.c. pan.

Although direct-action flat bottomed flushing cisterns are in universal use for new and replacement work there are still many thousands of the older Burlington or ‘bell’ high level cisterns in use, particularly in external w.c. compartments in older properties. Their function and failings should be clearly understood. Burlington pattern cisterns are invariably made of iron. Their essential feature is a well in the base in which stands a heavy iron bell. A stand-pipe connects to the flush pipe and rises, within the bell, to terminate open-ended an inch or so above ‘full’ water level. The bell has lugs cast into its base to permit water to pass freely.

To operate the flush the bell is raised, usually by means of a chain, and is then suddenly released. Its weight causes it to fall rapidly back into the well of the cistern and its conical shape forces the water trapped inside it up and over the lip of the stand-pipe. This water, falling down the stand-pipe into the flush-pipe, carries air with it thus creating the partial vacuum upon which siphonic action depends. Atmospheric pressure then pushes the water in the cistern under the base of the bell and into the flush-pipe to flush the w.c. The siphon is broken when water level falls to the base of the bell and air can enter.

Burlington cisterns are always noisy in operation. There is the clank of the descending bell, the rush of water from high level and the gurgle as the siphon is broken. Since they are usually connected directly to the main refilling, under mains pressure, is also noisy.

Another fault to which Burlington cisterns are prone, particularly after they have been in use for many years, is continuing siphonage. After the cistern has been flushed the siphon fails to break. Water continues to flow into the cistern through the ball-valve and there is a continuous flow down the flush-pipe that can be stopped only by ‘pulling the chain’ again at the end of the operation. A number of circumstances contribute to the this failing. After years of use the lugs at the base of the bell become worn, reducing the gap between the base of the bell and that of the well. Rust from inside the cistern and grit and debris from the water main accumulate in the well, further reducing the space through which air must pass in order to break the siphon. Coupled with a high water pressure and an efficient ball valve these two factors result in the rim of the well being continuously covered with water. The siphon can be broken only by pulling the chain and raising the bell again.

This trouble can usually be cured by the simple expedient of cleaning the rust and debris out of the well. In some cases it may be necessary, by turning down the stop-cock on the water supply to the cistern, to reduce the flow of water through the ball-valve. In others it may be possible to ‘build up’ the lugs on the base of the well with an epoxy resin filler such as ‘plastic padding’ or ‘isopon’, or to drill a hole through the metal of the bell an inch or so above its base to permit air to enter. A better solution is, of course, the more radical one of replacing the old and obsolete cistern with a modern ‘direct action’ one.

Direct action cisterns normally have a flat base though there are well-bottomed models available to facilitate the replacement of old bell pattern cisterns with the minimum of alteration to the plumbing. Like bell pattern cisterns, direct action ones have a stand-pipe connected to the flush-pipe that rises from the base of the cistern to a point an inch or so above water level. This stand-pipe is not however open-ended at this point. It is bent over in an inverted U and widened to form a dome with an open base extending almost to the bottom of the cistern. A rod connected by a metal link to the flushing handle passes through the dome to connect to the centre of a circular metal plate. The metal plate has a hole, or holes, in it to permit water to pass freely upwards but a kind of non-return valve, usually a plastic disc, closes these holes when the plate is raised.

These cisterns are often loosely referred to as ‘low level cisterns’ though they may, of course, be installed at low level, at high level or as part of a close-coupled suite. High level cisterns of this kind are operated by pulling a chain in the same way as a Burlington pattern cistern. Flushing takes place as the chain is pulled not, as with a Burlington cistern, when it is released. The most usual method of operating a low level direct action cistern is by depressing a lever. However press button operation is becoming increasingly popular and there are also pedal operated models on the market. These are particularly to be commended in commercial food premises where every means by which the operatives can avoid contamination of the hands should be encouraged.

Whatever the means adopted to induce flushing the action within the cistern is the same. The metal plate within the dome of the siphon is raised throwing water over the inverted U into the flush pipe. This falling water carries air with it to create a partial vacuum thus inducing siphonic action. Once siphonic action has begun water flowraises the plastic diaphragm or ‘flap valve’ on the plate to permit water to pass through freely.

Failure of this plastic diaphragm is the commonest fault encountered in direct action cisterns. The user finds that, whereas originally the cistern flushed promptly at the first attempt, several sharp jerks are necessary to induce siphonic action. The diaphragm is no longer blocking the holes in the plate and, when the plate is raised, water passes back into the cistern instead of being thrown over into the flush pipe.

To renew the diaphragm the flushing siphon must be removed from the cistern. First of all, tic up the arm of the ball-valve to prevent water from flowing in and flush to empty. Next unscrew the nut securing the external flush pipe to the threaded tail of the siphoning mechanism protruding from the cistern’s base. Disconnect the flush pipe. With some makes of cistern the siphoning mechanism is secured by bolts within the cistern itself. In most cases however the siphon can be withdrawn after unscrewing and removing the large nut immediately below the cistern’s base. As you loosen this nut the pint or so of water remaining after flushing will be released. Be prepared for this!

Once the siphon has been withdrawn the plate can be removed after disconnecting it from the ‘link’ connection with the flushing handle. It is important that the replacement diaphragm should be of the correct size. This will normally be purchased before the cistern is dismantled. If in doubt about the size required choose the largest-it can easily be cut to size with a pair of scissors. The diaphragm should overlap the plate and touch, but not drag on, the walls of the siphon dome.

Slow refilling is another fault that may be encountered with any kind of flushing cistern. After flushing the cistern should refill and be ready for use within two minutes. Failure to refill promptly is usually the result of the cistern being fitted with a high pressure ball valve where a low pressure or fullway model is required. Cisterns fed direct from the main normally require a high pressure valve. A cistern supplied from a roof storage cistern will probably fill sufficiently quickly if a low pressure valve is installed. Where the storage cistern is below roof level, perhaps in an airing cupboard only a few feet above the level of the flushing cistern, a full-way valve may well be needed.

If a valve of the correct type has been installed slow filling is almost certainly the result of the valve jamming because of an accumulation of hard water scale. The valve should be dismantled and cleaned as suggested in a preceding post.

Condensation is another trouble to which all w.c. flushing cisterns are prone. Iron Burlington pattern cisterns may be treated with two or more coats of an insulating anti-condensation paint but this treatment cannot be used to prevent condensation on the external surfaces of modern plastic or ceramic cisterns. As with all condensation problems the best remedy lies in warmth and ventilation. Consideration should be given to the provision of a radiant heat source directed towards the cistern and to improved means of ventilation, perhaps an electric extractor fan fitted into the window of the w.c. compartment.

It is worth bearing in mind that plastic cisterns, being of a self-insulating material, are less subject to condensation than ceramic ones. Cisterns supplied from the marginally warmer water of a cold water storage cistern are also less prone to condensation than those supplied direct from the main.

Bathroom w.c.s are more likely to have condensation troubles than w.c.s installed in a separate compartment. Here there are one or two steps that can be taken to reduce this nuisance. Refrain from drip-drying clothing over the bath. Always run one or two inches of cold water into the bath before turning on the hot tap. It may even be worth connecting a length of rubber tubing to the bath hot tap so that incoming water enters below the level of water already in the bath.

As a last resort consider insulating the inside of the cistern. Empty the cistern and dry it thoroughly. Then apply strips of expanded polystyrene wall paper lining to the interior of the cistern using an epoxy resin adhesive such as Araldite to retain the lining in position. Do not refill until the adhesive has set.

Finally there is the problem of noise. A w.c. that makes its presence known by its noise is a source of annoyance and embarrassment to the householder. Noise may arise from the cistern refilling, from the flush itself or from the contents of the w.c. flushing into the soil pipe. Noisy refilling depends upon the ball-valve and has been dealt with in a preceding post. So far as the noise of the flush is concerned it should be remembered that a low level suite is more silent in action than a high level one and that a close coupled suite—particularly if it is a double trap siphonic one-is the most silent of all.

The connection between w.c. outlet and soil pipe should always be of mastic or plastic material that does not readily transmit sound. In some cases it may help if a hard rubber pad is interposed between the base of the w.c. pan and the floor or if dry sand, or a layer of vermiculite chips, is run onto the ceiling of the room immediately below the w.c.

Attempts to silence a noisy w.c. are rarely wholly satisfactory. For reasons that lie within the province of a psychologist rather than a plumber, once a householder has become aware of a nuisance from noise the volume of the noise can be reduced many times but, to the hearer, will remain a source of annoyance.

For this reason it is important that the installer should foresee, and forestall, this problem before or during installation.

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