How to silence noisy and loud pipes from knocking

Knocking pipes can be both disruptive and cause long-term damage to a homes pipework system
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You get home from a hard day at work and are looking forward to a relaxing evening ahead. And then. Bang. Bang. Bang. Your pipes start producing a loud, noisy knocking. There goes any chance of peace and quiet.

Knocking pipes can be a cause for real concern. After all, hearing strange sounds coming out of appliances and places which should not be making noise is always a worry, but it seems doubly so when the problem is emanating from critical infrastructure like pipework.

The good news is that loud and noisy pipes, while tiresome and disruptive, will usually cause no long-term damage if dealt with properly. Most of the causes of knocking pipes you can treat yourself, although some may require the services of a plumber.

Here are five causes of noisy and loud pipes and how to silence their knocking.

Knocking related to copper pipes

Copper is one of the most frequently used pipe materials found in the home. It is durable, malleable and relatively cheap. It does however react to temperature, a characteristic that can lead to knocking.

If you have loud, noisy knocking coming from your pipes but it only occurs in conjunction with hot water use, then it is likely to be expanding and contracting copper. When the copper expands as hot water passes through it, it can bang into joints, brackets, other supports and even the walls of your home.

Expanding copper and the noise that come with it is nothing to worry about – it is a well-known property of the metal. You only need to take action if knocking pipes are causing too much disruption to your daily life.

The easiest way to try and prevent noisy pipes caused by copper expansion is by reducing the temperature of the water passing through them via your thermostat. Should this not prevent knocking, then easily accessible pipes can be wrapped in insulation to help reduce noise from when they encounter other surfaces.

If the copper pipes which are knocking are located behind walls, then you can call in a professional to access them and install insulation. This can be a costly and difficult process though, which often means that households learn to live with the noise instead.

Water pressure

If the water pressure within your home is set too high, then water will be coursing through your pipes far too quickly. As it does so, it will end up crashing around which will cause loud knocking.

Most households are able to set their water pressure via their boiler. Pressure should be between 1 and 1.5 bar. Consult your boiler to find out what the pressure is and if necessary, adjust the regulator.

High water pressure can cause long term damage to your home by overworking pipes and appliances. If you live in an older property with a boiler which does not have a metre or a regulator, then you should hire an expert to help you adjust the pressure.

Water hammer

Water hammer is a problem that effects pipes over time, leading to loud thuds and bangs whenever water is run. Pipework systems are fitted with air chambers which slow the flow when taps are turned off, preventing water crashing into valves.

When these air chambers begin to run out of air, water will hammer with increasing power into the valve. This in turn causes a loud banging noise – water hammer.

Fixing water hammer is usually quite straightforward. Turn off your mains water supply and turn on all your taps, emptying your pipework systems of water. Once no water is coming from your taps anymore, turn the mains back on. Water will begin to refill your pipes and once it starts pouring from the taps again, you can turn the taps off.

By draining your pipework system of water and then refilling it, you will replenish the air supply in the chambers to silence knocking pipes.

Blockages caused by central heating systems

Central heating systems create sludge and other particles which can end up entering your homes pipework systems. When this happens, these particles can bang into and scrape along pipes. Rather than a loud knocking, this creates a sound reminiscent of something sharp being dragged along or hitting metalwork.

Blockages in pipework systems can only be removed via draining. This is not something that you should undertake without training. If you suspect that the noise coming from your pipes is due to sludge and blockages, then you should contact a plumber to repair the issue.

Loose fittings

There could be one final – and often obvious – cause for knocking pipes. Pipework can become loose, either through wear and tear or because it was not correctly fitted in the first place.

This can lead to rattling, clanking and vibrations as parts of the system begin to rub and bang against each other. The simple solution for silencing noises caused by loose pipes is to identify where the issue is coming from and refit and tighten the pipework in question.

Pipe repair tape can be used to bind loose fittings tightly together to eliminate knocking. In some instances, pipework which is worn out might need to be replaced.

It is important to attend to loose fittings as soon as you notice a problem. Leaving pipework to continue to operate incorrectly can cause further complications down the line.

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