Flushing Cisterns

THE water closet flushing apparatus is known in the trade as a water waste preventer, because it delivers a measured quantity of water at each operation. The cistern fills to a predetermined level, and when the handle or chain is pulled down, all the water is discharged. Water company regulations forbid any device which would allow a continual flow of water to run down the w.c. Pan until a stopcock was turned off. In recent years attempts have been made to popularize a flushing valve that delivered a measured amount of water when the cock was turned, but such devices are only permitted when there is no danger of water being wasted.

Prevention of waste is more present in the mind of the companies than in that of householders. An example is the overflow pipe that projects through the wall from a cistern, and gives exit to water if the cistern level gets so high that it might overflow. People say, ‘Why don’t builders fix these pipes so that they just discharge into a head or trough on the down pipe outside the house?’ The answer is that the pipe is, properly speaking, a warning pipe, intended to warn the householder when water is being wasted by the failure of the regulating apparatus of the cistern, whether it be a flushing cistern or a storage tank in the loft. It must therefore discharge conspicuously to give prompt notice that something is amiss.

The overflow outlet is some little way below the top of the cistern or tank. Some modern low-down w.c. Suites have a vertical pipe for the overflow, with the top of this pipe open, and at the proper height for the purpose. This enables the lead pipe joining the overflow to the exit outside the wall to be connected at the bottom of the flushing cistern, instead of through one side.

In no circumstances of household economics is the old adage ‘Prevention is better than cure’ more applicable than in the maintenance of cistern ball valves. If entering a new house, ask the builder to supply half-a-dozen spare valve washers for the flushing cistern; also some for the storage tank in the roof. Replacement is easy when the spare washers are at hand; it is a very different matter when the householder has to fit a washer at short notice and without foresight. He then has to immobilize the cistern, which includes putting the w.c. Out of commission for the time, while he picks out the old washer and takes it down to the ironmonger’s to get another one of the same pattern.

How the Cistern Works

The ordinary cistern with a cast-iron body or shell is usually one of the valveless, siphonic type Open your own cistern and examine it; it is done by lifting off the lid, since though provision is made for fixing the lid by two bolts they are hardly ever fitted. The lever to which the pull-chain is fixed is-connected at the opposite end to the bell, which fits loosely over a stand-pipe that is practically an upward extension of the large pipe that carries water from the cistern: to the w.c. Pan below.

When the chain is pulled, the lever raises the bell; when the chain is released, the bell falls down by its own weight and splashes water up inside it, and so forces some over the top of the stand-pipe. This water carries down with it any air in the pipe, and sets up a siphonic action. Atmospheric pressure on the surface of the water in the cistern body forces this water also up over the top’ of the stand-pipe, and the flush continues until the well in the cistern is practically emptied.

Now let us see how the cistern is refilled. The inlet pipe at its inner end has a ball float valve fitted ; when the valve lever is raised to a certain height it forces in a plunger or piston that seals the inlet nozzle. There is a little recess in the inner end of the plunger, in which a washer of hard rubber is inserted, so making a water-tight seal to the small hole in the end of the nozzle. Owing to the comparatively long lever arm on the ball side, this hollow float can exercise great pressure as the ball is lifted up by the rising water. But if the washer is faulty, or has perished, even this pressure will not suffice to seal the nozzle, and so we get water continuing to flow when it should have ceased. Another cause of faulty action is a ball that leaks and becomes partly filled with water, so that it does not float properly, or ceases to float. Copper ball floats develop minute holes in time, through which water enters.

Going back to the sequence of operations, the chain has been pulled, and the cistern has emptied. The ball, no longer supported by the water, falls to the bottom, and water gushes in as the valve is opened fully; gradually, as the cistern fills, the water level rises, and the ball is slowly lifted until the leverage exerted closes the nozzle once again. There is little to go wrong with this type of cistern, and faulty action is almost aways due to the need for a new washer.

Fitting a New Washer

Turn off the water at the main, if the cistern is filled direct from the rising main. If it is supplied from a tank in the loft, find the outlet in the bottom (usually) which serves the flushing cistern; cut a broomstick to a taper at one end . so that it can be pushed into the hole in the storage tank from which the supply comes, thus cutting off the water to that appliance. In some houses there is a stopcock on the pipe that serves the flushing cistern, and it has merely to he screwed down.

The water being turned off, pull the chain to empty the cistern. It will be seen that the valve arm is connected to the valve proper by a split pin that goes through two holes in a bridle or a fork on the nozzle. Close the twin parts of the pin with a pair of stout pliers, when it can be pulled out by a bradawl or some such tool put through the loop at the opposite end. Take care of the pin, which should be of brass or some other non-rusting metal. The lever will now come away, and the plunger can be pulled out; note which way it fits, so that the slot is right side up on replacement. With a stout needle pull up the edge of the old washer until it can be grasped and extracted. The recess is larger below than on top, and the washer may have spread out somewhat. Put in a new washer, which will need easing past the narrower top entrance just mentioned. Replace the plunger, insert the lever, and push in the split pin; open out the prongs of the pin with a knife blade slightly, so that it will not pull out in working.

Turn on the water again, ordinary working pressure, and watch the cistern as it fills. When the valve shuts off, the water ought to be up to, or not far below, the line moulded on the inside of the cistern body. But one cannot tell for sure how a cistern will behave until some hours have elapsed; after apparently sealing, a valve may go on allowing a trickle of water to enter until the warning pipe again drips. Further, as the washer gets compressed by the working of the lever, the cistern may fill higher a few hours, or a couple of days, after the job has been done. If the cistern is frequently used such a defect will only become noticeable during the night, or some other time when it is not in use.

If the cistern does not fill high enough, so that the siphon action is defective, bend the lever arm up slightly; if on the contrary, too much water enters, bend the arm down a little. But for proper adjustment, the lever and ball should be taken off, for bending. There is not room in the cistern to make this adjustment with the arm in place, though it is often attempted. Incidentally, it is as well to mention (I) an improved float (flat-topped) which can be adjusted without bending the lever arm; and (2) an adjustable valve which can be regulated by turning in or out a screw at the end of the valve casing, again without interfering with the lever.

Leaky Float

If this is suspected, take out the lever and shake the ball to see if it contains water. If it does, find the hole or holes; it can be done usually by immersing the ball in a bowl of water and watching for bubbles. If the ball is full or almost full, shake it to detect the hole; a smear of soap will show a bubble at the spot to confirm diagnosis. Enlarge the hole a little with the tang of a small file; this will make it easier to get the water out.

Clean the area around the hole, apply soldering flux, and ‘tin’ the spot with solder; enough may flow into the hole to seal it, but if not, insert a copper nail or rivet, and flow solder over to make an air-tight joint. Scrub the patch afterwards with a nail brush and some soda water, to remove the flux, if an acid one has been used, and rinse well with clean water. A new ball float can be bought at an ironmonger’s or a builders’ merchant’s and is merely screwed on to the end of the lever after the old float has been unscrewed.

Low-down Cisterns

These work on another plan, as a rule, and the mechanism now described may be found also in ordinary flushing cisterns as well, see Figs. 3 and 4. Open up a flushing cistern and look at the mechanism. The principle is the same as in the bell type of apparatus, but the method of operation is different. The cistern handle is connected by a lever to the stem of a plunger or disk, this stem working through a hole in the top of an inverted cup which forms the lower portion of a U-tube; the long straight arm of the inverted U is a prolongation upwards of the flush pipe, and corresponds to the stand-pipe of the cistern, p. 271.

The handle and connecting parts are shown in Figs. 4 and 5. On pulling down the handle outside the cistern the plunger is raised; in rising, it lifts water up into the U-tube and thus starts the siphonic action, which continues until the cistern is emptied. The lever, links, split pins, etc., are of non-corrodible metal, and this type of appliance should not need attention, except occasional new washers to valves. But the lock nuts, or collars, on the handle spindle may shift, so that the lever connecting the handle with the link on the plunger stem may get out of alignment. This might cause the handle to stick down, but the adjustment is an easy matter, which entails loosening of the set screw to the collars and resetting the connecting rod at the proper distance.

Children should be warned not to treat this type of cistern roughly; no force is needed, and the handle merely requires to be gently pulled down to its full extent.

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