Date:30 April 2006
Some people (there’s a special name for them) would rather not think about cisterns, let alone fix them. Okay, so let’s talk about ball-valves…
FOR a start, you need to know how these things work. In a cold-water storage tank or toilet cistern, the water level is regulated by a ball-valve (or ball-cock) that is opened and closed by a lever arm attached to a float. When the cistern is at normal level, the float holds the arm horizontal and the valve is closed.
When the water level drops, the float lowers the arm and the valve opens to let more water in. The name ball-valve is derived from the early type of copper ball float. Modern floats are not always balls, and valves are often called float valves.
Ball-valves may be made from brass, gunmetal or plastic, or may be metal with some plastic parts. The size is measured by the inlet shank diameter; 15 mm or 22 mm sizes are usually needed for domestic cisterns. A cold-water storage tank or toilet cistern where the supply is direct from the mains needs a high-pressure valve. A toilet cistern supplied from the cold-water storage tank needs a low-pressure valve. If the pressure is very low because the toilet cistern is only slightly lower than the storage tank, a full-way valve is needed.
Low-pressure valves have wider inlet nozzles than high-pressure valves. If a high-pressure valve is needed, the cistern will fill much too slowly. If a low-pressure valve is fitted in a cistern supplied from the mains, water will leak past the valve.
Most modern valves can be changed from high-pressure to low-pressure operation either by inserting a different fitting into the inlet nozzle or by changing a detachable inlet nozzle. Some types are suitable for high or low water pressure without any alteration.
Fitting a new ball-valve
It’s time to fit a new ball-valve if the old one gets damaged or broken, or if you decide to change the type of valve – for example, to get rid of noise and vibration in a storage cistern.
You will need:
*Tools – Two adjustable spanners.
*Materials – Ball-valve with float (of same size as existing valve); two flat plastic washers to fit valve inlet shank (12 mm or 18 mm, usually supplied with valve).
1. Turn off the main stopcock to cut off the cistern water supply.
2. Use a spanner to undo the tap connector securing the supply pipe to the valve tail. You may need to hold the valve body of any securing nut inside the cistern steady with a second spanner.
3. Disconnect the supply pipe.
4. Undo the back nut securing the ball-valve to the cistern. Remove the valve.
5. Take off the back nut from the new ball-valve and put it aside.
6. Slip a flat plastic washer (and an inner securing nut, if supplied) over the new valve tail and push the tail through the hole in the cistern from the inside.
7. Slip another plastic washer over the protruding tail and screw on the back nut by hand. Tighten it half a turn with a spanner.
8. Refit the supply pipe tap connector to the new valve tail (use PTFE tape if necessary).
9. Restore the water supply and adjust the cistern level as necessary.
Adjusting the cistern water level
The normal level of a full cistern is about 25 mm below the overflow outlet. The level can be raised by raising the float, or lowered by lowering the float. If the cistern overflows, the level is too high because the float either needs adjusting or is leaking and failing to rise to close the valve (or the valve may be faulty).
ADJUSTING A BALL-VALVE
You will need:
*Tools – Possibly a small spanner, vice.
On a plunger-type valve with a ball float, unscrew and remove the float from the arm. To lower the level, hold the arm firmly in both hands and bend it slightly downwards, then refit the float. If the arm is too stiff to bend in position, remove it from the cistern and grip it in a vice.
On a diaphragm valve with an adjuster at the top of the float arm, lower the level by loosening the locking nut and screwing the adjuster forward, nearer to the plunger. Alternatively, use an adjuster nut or clip near the float to move the float farther away from the valve along a horizontal arm, or to a lower position if it is linked to the arm by a vertical rod.
REPAIRING A LEAKING FLOAT
For a permanent repair, you’ll need to fit a new ball float. But to get the valve back in action again until a new float is obtained, a temporary repair will do.
You will need: *Tools – Small spanner, sharp knife or old-fashioned tin opener, piece of wood to go across cistern.
*Materials – Plastic bag, string.
1. Raise the float arm to close the valve and cut off the flow of the water. Then tie the arm to a length of wood laid across the top of the cistern.
2. Unscrew and remove the ball float from the float arm.
3. Find the hole through which the water is leaking and enlarge it with a sharp knife or tin opener.
4. Drain the water from the float, then screw it back in position on the float arm.
5. Slip the plastic bag over the float and tie it securely to the float arm.
6. Release the arm and lower it into position.
How toilet cisterns work
Apart from some serious problems that require the services of a licensed plumber, most faults with a toilet cistern can be remedied by the handyman. Water usually flows into the cistern via a side inlet valve, controlled by a ball valve, which stops the water flowing well clear of the top of the cistern casing.
Bottom inlet valves are less common. As the water rises, so does a lightweight float.
The lever-action on the brass rod attached to the float slowly presses in a shaft, which stops the flow of water, by blocking the inlet nozzle with a rubber stopper or diaphragm.
There are two common cistern types: a beater valve and a siphon. The beater-valve cistern is the most common type now in use. The cistern must be watertight: if it overflows or leaks, there must be a malfunction.
The flush handle lifts the shaft of the valve, allowing water to rush downwards through the outlet port and flush the toilet. When flushing is complete, the beater valve is again seated on the outlet. The float drops, opening the ball-valve mechanism and allowing fresh water into the cistern via the inlet jet. As the tank fills, water pressure closes the beater valve completely. If the rubber beater valve leaks, you can easily replace it.
In a siphon cistern, a sprung plastic valve lifts a column of water up a wide shaft, which enters a narrow shaft leading to the toilet. This starts a siphoning action that is completed when the cistern is empty. The tank fills by the same mechanism as for the beater valve. The most common repair needed is replacing the floppy plastic siphon valve lining.
MINOR FAULTS WITH CISTERNS
The most common faults with cisterns are overflow, noise, continuous running and reduced flush – all of which can be fixed by the handyman. Always turn off the cistern stopcock before making minor repairs.
A cistern overflows because the inlet valve does not shut off when the water reaches its correct level. Check the following points.
1. If the water level is too high, bend the brass float arm downward to lower the water level.
2. The inlet valve washer may be faulty. Replace it.
3. The inlet valve may be clogged with dirt or grit.Dismantle the valve and clean it.
4. The float may be fouling the inside of the cistern. Bend the brass float arm so the ball is clear of all obstacles.
A noisy cistern is usually caused by water entering it too quickly.
1. Wait until the cistern fills, then turn off the stopcock.
2. Open the stopcock slowly until you get a satisfactory water flow without the irritating noise. You might have to adjust the flow rate.
3. On side inlet val
ves, you may be able to fit a proprietary noise reducer.
Where water runs continuously from the cistern into the pan, the outlet valve is the problem.
1. The valve rubber may be faulty. If so, replace it.
2. Dirt or a build-up of waterborne minerals may be preventing the valve from closing properly.Remove the valve and clean it.
3. On very old cisterns, there is a tiny groove in the brass plate under the suction washer which may need cleaning out. The groove enables the suction to break once the cistern has emptied.
A reduced cistern flush can result from one of two causes.
1. The water level setting is too low. Bend the brass float arm upward to raise the level.
2. The outlet valve suction washer may be faulty. If this is so, you can usually hear the valve fall back into place just after the flushing action starts. Remove the valve and replace the suction washer.
An average toilet cistern uses about 11 litres of water for every flush. As it is not necessary to use this amount of water every time the toilet is used, billions of litres of water are wasted every year. This is expensive both in terms of cost to the householder and water conservation.
Some homeowners place a brick in the cistern to reduce the amount of water used. This is hazardous: should the brick fall over when the cistern is empty, it can punch a hole in the tank. It will also interfere with outflow. It is safer to reduce the amount of water in the tank by bending the float arm downwards.
If you cannot hold the rod and bend it in the cistern, remove it by releasing the split-pin holding it into the valve, and bend it over a table-edge. Reinstall the rod.
Clearing a blockage in a toilet
The usual faults with a lavatory pan are blockages or leaks. A leak from the pan outlet is not difficult to repair, but a cracked pan will have to be replaced.
If the flush water rises almost to the pan rim then ebbs away very slowly, there is most likely a blockage in the pan outlet or possibly in the drain it discharges into.
1. To clear the pan, take a plunger and push it sharply onto the bottom of the pan to cover the outlet. Then pump the handle up and down two or three times.
2. If this does not clear the pan, use a flexible drain auger to probe the outlet and trap.
Alternatively, if you suspect that the blockage might be caused by tree roots in the outside drains, drop a copper sulphate tablet such as Rootox into the pan. As the tablet dissolves, the copper will burn off the intruding roots. Do not use copper-based chemicals in septic systems.
3. If the blockage persists, have the pipes cleared with an “electric eel”.
4. With the blockage cleared, flush the cistern to check that water is entering the pan properly. If the flow into the pan is poor or uneven, use a mirror to examine the flushing rim. Probe the rim with your fingers for flakes of rust or debris from the cistern that may be obstructing the flush water.
If you have no plunger, you may be able to use a mop or broom tied round with rags. Or stand on a stool and tip in a bucket of water in one go.
Getting rid of water hammer
Banging in water pipes is caused by back pressure building up when a tap is turned off suddenly. Handoperated taps are turned off slowly, but the automatic shut-off valves on many appliances turn off suddenly. The rushing water bangs into a solid wall and rebounds, sending shock waves back along the pipe.
The size of the shock waves depends on the volume and pressure of the water in the pipe, and water hammer can often be eliminated by reducing the flow to ball valves, washing machines and dishwashers – any device that automatically switches off the flow. An additional advantage of this is that water pressure in other parts of the system, such as in the shower, will not be radically affected when the machine or ball valve switches the flow on or off.
Rattling and banging in pipes can sometimes be fixed by fitting additional pipe fixings. There should be a bracket holding down the pipe along every 600 mm of its length. Having rubber cushions between the pipe and roofing timbers can also reduce rattling. A plumber can also make a “cushion” for the water shock waves. He will braze together several lengths of pipe of increasing diameter and plumb this on to the end of a run of pipe.
*From the , published by Reader’s Digest under franchise to the Heritage Collection.