Fixing Problems with the WC

Fixing Problems with the WC, or toilet, may be just plain annoying—such as a slow-filling cistern— or more serious—such as a cracked outlet joint. But none requires much more than basic plumbing skills and common sense to put right

The WC is a particularly hardworking, and fairly complex, piece of plumbing apparatus. So it is prone to a number of faults. Though these are rarely difficult to put right, the various jobs are made a lot easier if you know something of how a WC works, and what happens when you pull the lever and the pan is washed automatically clean.

There are two main parts to most WC systems—the pan itself, and a cistern above it which holds the water to flush the pan.

The WC pan

There are two basic types of pan. The washdown uses the force of the descending flushing water alone to push the contents into the soil pipe. In the more modern siphonic system, the impulse of the water flush creates a vacuum in the pan so that atmospheric pressure will force the contents out of the pan. The flushing water merely serves to refill the bowl. The siphonic suite is more complex, and therefore more costly, but it is quieter in operation.

All pans have a built-in trap to prevent unpleasant gases coming back up the soil pipe from the sewer or cesspit. The shape of this varies according to the type of pan, but it always includes at least one ‘U’ bend which remains filled with water.

Traditional UK pans have their outlet either vertically downwards or nearly horizontal. Modern UK pans often have a short horizontal outlet at the back to which you can fix a number of patterns of connector pipe—this makes it possible to accommodate the vagaries of most existing waste systems when fitting a new pan. Whatever the type of outlet, it is always at the back of the pan.

Canadian pans have vertical outlets that appear from underneath the pan itself. This makes for a neater external appearance, and means that the large, ugly, soil pipe is hidden from view below floor level.

The WC cistern

The purpose of the WC cistern is to hold just enough water to clean out the bowl.

Modern cisterns are usually either low-level, with the cistern just above the pan and connected to it by a short flushing pipe, or close coupled, in which the cistern and pan form a single unit. Old-fashioned suites may be high-level, with the cistern as much as 2m above floor level.

UK cisterns usually have a siphonic-type flushing valve—pressing the lever jerks up a diaphragm within a U-shaped tube, pushing water over the top of the U and down into the pan. Siphonic action keeps the flap up and water flowing until the cistern is empty; then the inlet valve opens and refills the cistern.

Canadian flushing systems look less complex. The lever lifts a simple valve cover—a flapper or ball—at the base of the cistern. The rush of outflowing water prevents the valve cover from closing again until the cistern is nearly empty. Then the inlet valve opens and refills the cistern; some of the incoming water is diverted through an overflow tube to replenish the trap-sealing water in the pan. Alternatively, there may be no cistern at all; just an automatic valve connected direct to the water supply. This lets through a metered amount of water, then closes.

There are several types of inlet valve. They are strictly called ‘float valves’, because they all have a member which floats on the surface of the water and is connected to the actual valve mechanism. As the cistern empties, the movement of the float opens the valve to allow the cistern to refill. In most cases, the floating part is a ball, connected to the valve by a long arm—so these valves are usually known as ball cocks, or ball valves.

Cisterns need an overflow warning pipe, in case the ball valve fails to shut off when the cistern is full. In the UK, the overflow pipe usually discharges outside the house. In Canadian cisterns, the overflow tube discharges direct into the WC pan.

Faults with a WC can be divided into plumbing faults and accidental damage.

Failure to flush

First check the water level in the cistern; if this is very low, the fault lies with the ball valve. Try pushing the float below the water level. If water rushes in then the valve is working correctly, but the float is closing it at too low a water level. You can correct this by gently bending the ball arm upwards.

If no water enters the cistern when you push down the float, then the inlet valve is blocked: for repair, see Overflowing cisterns, below.

If the water level in the cistern is not low, then you have a fault with the outlet flushing valve. Before you dismantle it, though, check that the various levers and wires are intact, and that moving the handle actually does move the valve flap. Broken or stretched linkages are usually easily replaced.

To replace a worn diaphragm, first tie up the ball valve arm to stem the water supply. Then empty the cistern— first by flushing it, then by mopping up any remaining water with a sponge.

On a close-coupled suite you must next remove the cistern from the pan. In all cases, undo the nut under the cistern securing the flush pipe to the siphon unit, and also the nut securing the siphon to the cistern body, then remove the whole siphon unit. Note the position of the parts as you con- tinue disassembly.

Replace the diaphragm with one of the correct size and reassemble the siphon unit. You can obtain a new diaphragm from hardware shops or builders’ merchants, or cut one from a piece of heavy PVC sheet using the old one as a template.

Check that the plunger moves freely in the siphon unit, then replace the unit in the cistern.

Flush fails to clean pan

In the case of the flush not efficiently clearing the pan, either the pan is not level or the flush pipe is blocked.

The washdown system is more sensitive to the pan not being level because of its dependence on the momentum of the flushing water. This should flow around each side of the flushing rim and meet centrally at the front of the pan. But if the pan is tilted slightly, the flush will be stronger on one side than the other and the result will be a ‘whirlpool’ effect which is inefficient.

Use a spirit level to check that the pan rim is level. If it is not, loosen the pan base retaining screws, and pack pieces of wood or linoleum under the lower side. Also, check the channel under the flushing rim for obstructions and clean it if necessary.

If the pan is level, check that the flush pipe enters the pan squarely and that there is no obstruction at this point.

With a Canadian flush-valve toilet, there is a regulating screw which adjusts the amount of water in each flush. If altering this fails to cure an ineffective flush, then the valve will have to be dismantled and cleaned.

Overflowing cistern

If water pours out of the cistern overflow pipe, it is likely that the float is perforated and waterlogged. In this case you must replace a faulty float with a new one, though as a temporary cure you could shake out the water and tie a plastic bag around it.

If on the other hand water is only trickling from the overflow pipe, it is more likely that the ball valve washer needs replacing—although sometimes the trouble is due to a speck of grit preventing the washer from seating properly on the valve nozzle. In both cases, it is necessary to dismantle the valve.

There are several different types of ball valve, but the most common UK ones are the Portsmouth, Croydon, Garston, Equilibrium and Torbeck. To dismantle any valve, the first step is always to isolate the water supply to the WC cistern.

In the case of a Portsmouth or Croydon valve, remove the split pin on which the float arm pivots and place the float and arm on one side. With a Croydon valve the plug will simply drop out of the valve body. To extract the plug from a Portsmouth valve, insert the blade of a screwdriver into the float arm slot and push the plug out of the end of the valve body, taking care not to let it fall.

At this stage, if possible, get an assistant to turn the water supply briefly on and off to your command so that the pressure ejects any grit that may be blocking the valve nozzle. Reassemble the valve and attach the ball arm and float, then turn on the water supply and see if the valve seals off the supply effectively. If it does not, the washer is defective and you must replace it.

The plugs of both types of valve are in two parts, but the cap that retains the valve washer is often difficult to remove. You can try applying some penetrating oil and warming the end of the plug gently, but you must not damage it by rough handling. If the cap refuses to budge, pick out the old washer with the point of a penknife and force the new one under the flange of the cap, making sure that it rests flat on its seating.

Clean the plug with fine emery paper, then wrap the paper around a pencil and clean the inside of the valve body. Smear a thin coat of petroleum jelly inside the valve before you reassemble it.

Some modern cisterns are fitted with a Garston ball valve. In this case, shut off the water, remove the split pin and the ball arm as before, then unscrew the cap and pull out the rubber diaphragm. Check that there is no grit or foreign matter in the nozzle as described above. Otherwise, replace the diaphragm and reassemble the valve in the reverse order.

If a plastic Torbeck valve sticks, the most likely cause is dirt on the valve seat. Slowly raise and lower the ball arm a few times. If this fails to remedy the fault, shut off the water, unscrew the front cap, and wash the diaphragm in clean water. When you reassemble the valve, make sure that the dia- phragm is the right way round.

The main type of Canadian valve operates vertically, like a Croydon valve, at the end of a vertical water inlet which enters the cistern through its base—this makes the plumbing look neater. To dismantle, remove the two pins holding the rather complicated linkages which connect the valve piston to the float arm, and pull the piston upwards. There are two washers to replace—one in the bottom of the plunger and another one held in a groove around the circumference.

There is also a diaphragm type of valve, which also sits on the top of a vertical inlet tube. The cover is usually held in place with four screws; otherwise repair is much the same as for a UK Garston valve.

Canadian flush-valves are either of the diaphragm or piston type. Though the mechanism is usually a little more complex than for their float valve counterparts, disassembly, cleaning and repair is much the same. You can usually get kits of replacement parts.

Slow filling

The cistern should refill within two minutes of flushing. If it fails to do so, there is almost certainly something wrong with the ball valve. In this case dismantle the ball valve as described above and clean it. One problem in the UK is that a high pressure valve might have been fitted— this is rarely needed unless the cistern is fed direct from the mains. Normally, a low-presure valve should be fitted, but in the event of the storage cistern being less than a metre or so above the WC cistern, then a full-way valve should be used.

Excessive noise

A WC can create excessive noise during refilling or flushing. Noisy refilling may be due to ball bounce and vibration, and this can often be reduced by tying a plastic flower pot to the float arm so that it is suspended, right way up, in the water a few centimetres below the float itself. The pot serves as a kind of ‘sea anchor’, and prevents the float rising and falling with every ripple.

The best solution, however, is to change the ball valve for either an Equilibrium or a Torbeck valve.

With a Canadian valve, check that water from the refill tube goes squarely into the overflow pipe.

The best solution to noisy flushing is to replace the suite with a double-trap siphonictype.

Leaking outlet joint

In the case of a leak here, use a hammer and plugging chisel to rake out the existing jointing material. Bind two or three turns of proprietary waterproof tape around the outlet pipe and caulk this down hard into the soil pipe socket. Then fill the space between the outlet pipe and the socket with a non-setting mastic, and complete the joint with two or three turns of waterproof tape over the mastic filling.

Cracked pan

The only solution to a badly cracked pan is to fit a new one. Before removing the old one, make sure the replacement will fit by checking the size, position and angle of the soil pipe where it goes into the pan. In Canada, you need to know only the rough-in distance— usually taken as the distance from the wall to the centre bolts holding the pan to the floor.

Tie up the float valve, flush the cistern, and scoop out the water in the bottom of the pan—all this helps prevent water damage in the case of accidents.

If you are replacing the pan of a close-coupled suite, the cistern will have to be removed and you will have to turn off the water so that you can disconnect the suite at the inlet pipe. Otherwise disconnect the flush pipe at the pan. Disconnect the pan at the outlet pipe. Both these joints might just pull apart, or the jointing material might be non-hardening and you can dig it out with a sharp tool. If cement or similar has been used for the joints, your best bet is to break the pan, taking care not to break the flush pipe or soil pipe. Bits of the pan then left attached to the pipes can usually be carefully chipped away. Unscrew the pan from the floor and lift it away.

Offer up the new pan, with its top surface horizontal both from side to side and front to back, and the inlets and outlets should mate perfectly. There is usually little leeway on the flush pipe— drastic alterations can affect flushing performance—so discrepancies may have to be taken up at the soil pipe connection. Many problems of mis-fit with UK soil pipes can be overcome with a flexible plastic connector, such as one of the ‘Multikwik’ range. With Canadian systems, there is no room for manoeuvre here: you will probably have to try a different pan.

There are three methods of fixing the pan outlet to the soil pipe in the UK: with a rigid plastic connector and rubber insert; with a flexible plastic connector of the ‘Multikwik’ type; or with a traditional cement and gaskin joint.

The plastic connectors simply push over both ends. If you are fixing the outlet directly to the soil pipe’ with a traditional joint, first lay two or three turns of gaskin around the joint socket to stop cement running down the soil pipe. Tap this purposefully into place. Then make up a mix of plumbers’ quick-setting cement. Lower the bowl over the drain flange, pushing down with a twisting motion to seat the gasket properly; avoid lifting the bowl once it is in position.

On a wooden floor, screw the pan in place using brass screws, taking great care not to overtighten, and making sure the pan stays level.

On a solid floor, make a key in the floor by cutting grooves in it with a bolster. Make up a mix of one part cement to three of sharp sand and trowel this over the key. Then lower the pan over it, making sure that the pan outlet enters the collar of the soil pipe or connector. Rock the pan slightly to settle it, and make sure that it is level with a spirit level.

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