Water flowing through pipes and into vessels can cause a variety of noises, all of which may be quite annoying in their own way.
Sometimes we put up with these noises because of the cost of curing the problem. The key thing is to install the system correctly in the first place and most of the problems will never occur.
The various kinds of noise you might have include:
C
C one or two loud banging noises, usually when a tap is closed C
C a series of rapid banging noises C
C humming in the pipework C
C a shushing noise as water passes through the pipework C
C noise generated by a pump C
C creaking floor timbers C
C splashing noises as water refills a cistern C
C noises from a boiler, like a kettle boiling C
C gurgling noises in the pipework C
C gurgling noises from an appliance waste trap.
This is not an exhaustive list, but it represents the more common situations dealt with below.
ONE OR TWO LOUD BANGING NOISES, USUALLY WHEN A TAP IS CLOSED
This is the classic ‘water hammer’ sound. It is the result of a tap or stopcock jumper/washer or non-return valve rapidly
closing, creating a sudden back-surge of water. This noise can also be created by pipework that has not been fixed securely, so that it flaps about. Securing loose pipework may cure the problem, but if not:
1 Slightly turn down the incoming supply stopcock, reducing the incoming water flow rate and thereby preventing these back-surges.
2 Where water flow cannot be compromised, it is possible to purchase a small expansion vessel to take up the shock wave.
This expansion vessel, designed specifically to deal with this problem, is similar to that used for an unvented domestic hot water system, but a lot smaller.
A SERIES OF RAPID BANGING NOISES OR HUMMING IN THE PIPEWORK These different sounds are, in fact, caused by the same thing.
The sounds are generated by the float-operated valve in a storage cistern rapidly opening and closing as it rides up and down on the small ripples or waves formed on the surface of the water in the cistern. The waves are formed as water flows into the cistern when the float-operated valve opens to make up the water level after some water has been drawn off.
If the plastic cistern has been installed without the metal reinforcing piece that came with it, the cistern wall will flex as the float rides over the ripples on the water. There are several possible cures for this problem:
1 Secure the float-operated valve (ballvalve) by fully supporting the cistern wall.
2 Replace the normal 100 mm diameter float with a larger ball float.
3 If a larger float cannot be obtained, secure a damper plate to the lever arm to create a larger surface area (see Figure 5.1).
4 Fit a baffle within the cistern to prevent waves forming. This is basically a dividing plate to reduce the total surface area of the water.
5 Turn down the incoming supply stopcock to reduce the water flow into the home.
A SHUSHING NOISE AS WATER PASSES THROUGH THE PIPEWORK This noise often occurs if the installer has failed to take the small internal burr off the pipe when using a copper tube cutter.
It is also sometimes generated where pipework has been run within a timber stud wall. The plasterboard over the timber studwork acts as a resonator, amplifying the sound of the water flowing through the pipe. When pipes are run within timber stud walls, they should ideally be insulated and the pipe clips placed on rubber or felt mountings to stop this transmission of noise.
Curing this problem after the event is often very difficult. Again, try turning down the supply stopcock. It may cure the problem or at least improve things. Sometimes this noise is generated in central heating pipework, in which case try turning down the pump pressure setting.
Remember this
One of the easiest and best cures for noisy cold water pipework that is subjected to mains supply pressure is to turn down, or slightly close, the inlet stopcock. In some areas this valve needs to be open only half a turn or so.
damper plate
float-operated valve
metal reinforcement to plastic cisterns
3
Figure 5.1 Preventing ballvalve murmur
NOISE GENERATED BY A PUMP
Where this problem occurs with a central heating system, turning down the setting – if a variable speed pump has been installed – will generally alleviate the problem. However, this may create a different problem in large heating systems in that the furthest radiators from the pump may not get warm enough.
Where the pump noise comes from a shower booster pump, it may be that the pump has not been fitted with flexible connections and on to a flexible mounting, and so this would need to be provided if necessary. Also check that the pump is not touching anything that would act as a sounding box and elevate the noise level.
CREAKING FLOOR TIMBERS
This is generally the result of pipework running below timber floors and passing through the floor joists with notches that are barely large enough, or pipes that have been run touching one another. The noises are the result of the copper pipes expanding and contracting as they heat up and cool down.
When passing copper pipework through notches that have been cut in the joist, ideally a felt pad or piece of carpet underlay should be laid to dampen any movement noise caused by the pipe expanding or contracting. The only option is to lift the floorboards and investigate.
SPLASHING NOISE AS WATER REFILLS A CISTERN
You can eliminate this noise by fitting a polythene collapsible silencer tube (see Figure 5.2). These are often fitted as standard to WC flushing cisterns but are rarely fitted to cold water storage cisterns. Within the loft and inside an insulated cistern the noise is rarely heard, but if the cistern is above your bedroom in a quiet house, it is the sort of noise that sometimes, at night, seems like Chinese water torture.
If you cannot get a polythene silencer, sometimes fitting an inclined ramp, on to which the water can discharge inside the cistern, eases the problem.
NOISES FROM A BOILER, LIKE A KETTLE BOILING
Noises from the boiler, such as the sound of bubbling water, can have one of several causes. If the system used to work well and the problem has only just started for no apparent reason, it is possible that a narrow pocket of air has become trapped within the boiler, perhaps as a result of limescale or corrosion. The noise is generated by the formation of steam and its subsequent condensing within this area of trapped air. The only remedy, apart from a new boiler, is to treat the system with a descaling solution. Where a power flush is sought, this may require the services of a reputable heating engineer; however, depending on the age of your system and the materials it is made from, e.g. aluminium, copper or steel, several manufacturers produce chemical cleaning solutions, available from any plumbers’
merchant. These come with the necessary application
instructions and can be administered to clean out your system.
Remember this
Using acidic solutions to remove sludge that has been blocking a corroded radiator or preventing a leaking joint may expose the fault and leave you with a system that now leaks. But you must remember that the fault was there already and at least you will find the leak under controlled conditions and it will not simply spring up when you are not at home.
polythene silencer tube
Figure 5.2 Fitting a polythene silencer tube
Another cause of a noisy boiler could be the flame impinging directly on to the heat exchanger within the boiler, causing local hot spots where steam forms and collapses. This requires a specialist heating engineer to make the appropriate adjustments to the flame and, where necessary, to investigate the cause further.
GURGLING NOISES IN THE PIPEWORK
These sounds are to some extent to be expected in a new system, as trapped air is slowly released from the system via the vented pipework. However, if these bubbling noises continue to flow up through the system, it suggests a much deeper problem. It is possible that air is being drawn into the system, in particular the heating system, because a circulation pump is incorrectly located (see Chapter 3).
Air being continually drawn into the system increases the speed of corrosion within the system and, apart from the noise generated, it should still be rectified in order to extend the life of your system.
GURGLING NOISES FROM AN APPLIANCE WASTE TRAP
These noises are the result of water being siphoned out from the trap. See Chapter 1 for a discussion of this problem.