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Pipes Knocking? Faucet Won't Work? Your Plumbing Could Have An Air Lock

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Despite what you might think, air locks aren't just for space ships and sci-fi novels. In fact, if you have a malfunctioning faucet, you might just have an air lock in your own home. Fortunately, diagnosing and removing air locks from your plumbing should be simple, and you can even take steps to prevent getting one again.

How Does An Air Lock Form?

Though we typically think of plumbing as airtight, small amounts of air pass through most pipes all the time. Because air bubbles will always rise to the surface, it's possible for them to get trapped in small areas of pipe, like the top of a U-bend. Once air starts to accumulate in one area, new air bubbles will become trapped there more easily, which means eventually you have a significant pocket of air in a small section of pipe.

Depending on your system's water pressure, this air pocket may be strong enough to disrupt the flow of water and even stop it completely. To get through, water has to overcome both gravity and air pressure, which can also put a strain on your plumbing.

What Are The Signs Of An Air Lock?

Air locks have some pretty unique symptoms, so it shouldn't be too hard to tell if you have one in your pipes. For starters, the pipes themselves will make knocking or tapping sounds whenever the water is run through them. You may also be able to feel a temperature difference between an area of the pipe with water in it and the higher point where air is trapped.

Faucets that misbehave may also be indicating an air locked pipe. Water may sputter slowly out of one faucet or not come out at all, while others in the home work just fine. On mixed temperature faucets, one temperature of water may not come out, while the other flows freely. Usually air locks happen in hot water pipes due to the lower pressure, so if the hot water won't come out and you hear the characteristic knocking sound, you can be reasonably sure it's an air lock you're dealing with.

How Can You Fix An Air Lock?

The problem can be solved in a couple of different ways, some requiring more plumbing knowledge than others. For starters, try just turning on all of the faucets in your home at once. This helps to increase the pressure in your plumbing, which can force the air out. If this doesn't help, check your shut off valves to ensure that they are fully open, allowing as much pressure as possible into your pipes. Finally, if you think you know where the lock is in your pipe, check to see if there's a release valve you can open to let the air escape.

If you try all of that and still have trouble, there's one more fix you can try. Disconnect your washing machine and use one of the hoses to attach the hot and cold water connections to one another. After making sure the hose is secure, turn both on for a few moments. Because cold water has a much higher pressure than hot, allowing the cold water into the hot pipes will force out the air bubble.

Should You Worry About An Air Lock?

Bubbles of air are not dangerous to your plumbing in and of themselves. They merely represent an inconvenience every time you have to remove them. However, if you frequently get air locks in your pipes, it could be a sign that something is wrong with your plumbing. If the cause is low pressure throughout the home, you may want to consider investing in a pressurizing system from your local home improvement store.

If your water system is not low pressure for the whole home and you keep having trouble with a particular area of your plumbing, you should contact your local plumber. Low pressure in just one area and large amounts of air getting into the pipes may indicate an undetected leak or other serious problem is keeping your water from flowing smoothly.

Air locks may sound futuristic, but they're fairly simple to find and fix once you know what to look for. If you'd like to know more about preventing air locks or you have one that just won't go away, it's a good idea to get in touch with your local plumbing contractor for an inspection. You could be just a loose pipe or an open valve away from having perfect water pressure again.