5 Sure Ways to Stop Water Hammers

Noisy water pipes are never a sign of good things. Ideally, water pipes should be quiet and the only sound you should hear if any is the flow of water.

A water hammer, scientifically known as a hydraulic shock happens when water flowing to a faucet or fixture under pressure is suddenly shut off, causing it to change the direction of flow just as sudden. This causes vibrations and rattling, as the water pipe bangs against the wall and other pipes.

Apart from the annoying sound of water hammers, this phenomenon is also potentially dangerous, and could result in even more expensive repairs. The constant vibrations and banging of the pipes could stretch them beyond their limit resulting in leaks or even bursts. It could also result in premature failure of appliances and leaking valves or faucets.

Water hammers are not very noticeable in a house with plastic pipes (PEX) but the dangers are not any lesser than those in steel or copper water pipes. If this is what you have, get access to your water pipes and monitor their behavior when a washing machine or dishwasher is filling, and precisely when the water supply is shut off.

If you notice the water pipes vibrating and rattling when the water to the washing machine or dishwasher is shut off, you have a water hammer that you need to fix. Constant failing of faucet washers and fixture valves is also a sign of this problem.

To fix a water hammer in your water pipes, consider installing an air chamber or drain water out of it if you already have one installed. Installing a water hammer arrestor, reducing the water pressure in the house with a pressure reducing valve or securing loose water pipes will also help to fix and prevent water hammers.

How to Stop Water Hammers

Fixing a water hammer can be a very simple process for some people. You might not even need to buy anything.

In this post, I will show you how you fix the water hammer problem in your house in 5 simple ways. Some of the methods work well when combined together.

Fix a water hammer on your own will cost $0 to $50 but a plumber will cost around $100 or more depending on your area and the difficulty of the problem. If you need to buy parts then the cost will increase but will hardly exceed $300.

The following are the best methods of stopping a water hammer:

1. Install/Drain an Air Chamber

water-pipes-air-chamber
Image: Chest of Books

An air chamber is a vertical pipe (usually about 6 inches long) that is installed before the fixture valve/faucet. Since the chamber is higher in elevation than the valve, it is usually filled with air and not water.

When water flowing to a faucet or a fixture is turned off suddenly, instead of it bouncing back forcefully and creating a water hammer, it flows into the pocket of air in the chamber which acts as a shock absorber.

A plumber will fabricate and solder an air chamber onsite while installing water pipes and/or fixtures using ordinary water pipes but commercial air chambers are also available. Seasoned DIYers can install an air chamber on their own but if you are not very confident you should call in a licensed plumber to do it for you.

An air chamber basically creates a tee junction on the water pipe carry water to the fixture. To install it you will need to shut off water to the fixture and drain out the water in the pipes first.

When that is done, use a pipe cutter to precisely cut off a section of the pipe and fit in the tee. Solder the tee junction on the water pipe and then thread in the vertical pipe section.

Unless you live in a very old house, most modern houses have air chambers already installed. You can however still have water hammers even with an air chambers in place. How is this possible?

With time, the vertical pipe is filled with water, and its shock-absorbing properties are compromised. When that happens, the water travelling to the faucet or fixture will have nowhere to dispose off its energy after the fixture valve/faucet is shut off, resulting in a water hammer.

To fix this problem, you will need to drain out the water from the air chamber. When that is done the air chamber will start working as new all over again.

Most air chambers are not visible since they are concealed inside the walls. There is no easy way to tell if you have one in place unless you have an access panel.

The only way to find out is to drain the water in you water pipes and check if the problem stops.

How to Drain Water from an Air Chamber

While draining water out of your air chamber, you need to be carefully not to have an airlock in your pipes. An air lock happens when air is trapped inside you water pipes resulting in sputtering faucets.

You want to have air in your air chambers and not any other places in your water pipes. Here is how to drain water out of you air chambers:

  • Turn off the main house water shut off valve. The shut off valve is located about 5 feet from where the main water pipe enters the home, usually next to the water meter. You can also find it in the crawl space or in the basement near the water heater.
  • Open the highest water faucet (usually upstairs) but if you have no upstairs open the faucet farthest from the shut off valve.
  • Drain the water from the water pipes by turning on the lowest faucet in the house, usually one in the basement. With both the highest and lowest faucets open, water will drain out of the pipes and air will flow in.
  • After all the water has drained out, turn off the lowest faucet but keep the highest one open. You want to flush air from the pipes through the open high faucet.
  • Open the main water shut off valve and start monitoring the open faucet. At first water bubbles will be sputtering out. Leave it open until a continuous and smooth flow of water starts.

All the water pipes in the house will be filled with water but the air chambers will be filled with air. Go ahead and check if the problem is fixed by opening water to a faucet (or running an appliance like washing machine or flushing a toilet).

In some instances, the effectiveness of air chambers can be impeded by corrosions and and clogging by mineral deposits, especially in areas with hard water. In such a situation, remove the cap on the air chamber and clean the inside.

Installing an air chamber with a pipe bigger than that of the water pipe is effective in eliminating the effects of mineral deposits.

2. Install a Water Hammer Arrestor

water-hammer-arrestor

A water hammer arrestor is the modern version of an air chamber. Just like the air chamber, the water hammer arrestor (also known as a water shock arrestor) is installed just before the valve or faucet using a screwed-in tee.

Water hammer arrestors contain an air bladder inside which helps to dampen the effect of the water hammer. When water flowing to a fixture is shut off suddenly, the air in the bladder absorbs the shock, ensuring that your water pipes remain quiet.

If you use water from a well, a water hammer arrestor works just like the pressure tank. Another example is the thermal expansion tank installed in water heater cold-water supply pipes.

A water hammer arrestor is more practical than an air chamber especially in commercial buildings where water pressure is required to be high. Some building codes actually favor water hammer arrestors instead of air chambers.

One advantage of water hammer arrestors over air chambers is that you do not need to recharge them. Since the air bladder is sealed, water cannot fill it up so you do not need to keep draining water out of it.

A water hammer arrestor will however need to be replaced if the bladder raptures. If you have a water hammer arrestor already installed and you suddenly start experiencing water hammers, there is a possibility that the bladder has raptured (usually due to high water pressure) causing it to be waterlogged. The arrestor will need to be replaced.

Water hammer arrestors are relatively easy to install and most people will not need the services of plumber. It is however important to make sure that you install 2 of them, one on the cold and the other on the cold water supply pipes.

3. Reduce the Water Pressure

pressure-reducing-valve

The ideal/normal water pressure to your house should be between 40 and 60 pounds per square inch (psi). If the water pressure in your house is too high, the water will carry with it more force resulting in loud bangs and vibrations when a faucet or fixture is shut off suddenly.

The first thing you need to do is to check the water pressure in your house. Buy (if you do not already have one) a pressure gauge and connect it to the outside water faucet. Make sure that the faucet is connected to the same water supply pipe as the rest of the house.

To get an accurate result, make sure that there is no fixture running in the house while checking the water pressure. A running washing machine or dishwasher will considerably lower the pressure.

Turn on the faucet and check the water pressure on the gauge. You can also connect the gauge to the water heater drain valve and check the hot water pressure.

If the water pressure in your house is too high, you will need to adjust it at the pressure reducing valve, assuming you have one installed.

This is how to adjust the water pressure in your house:

  • Locate your pressure reducing valve armed with an adjustable wrench and flathead screwdriver.
  • Use the wrench to loosen the nut on the PRV.
  • Use the flathead screwdriver to turn the screw on the PRV counterclockwise. Keep checking the reading on the pressure gauge and turning the screw accordingly until you get to your desire water pressure.
  • Tighten the nut to secure your adjustments.

If you do not have a pressure reducing valve in your home, consider bringing in a plumber to install one for you. Apart from water hammers, high water pressure causes premature failure of appliances and leaking fixtures.

4. Secure Loose Water Pipes

A water hammer is worsened by loose pipes. Water hammers can actually loosen up the pipes in your house. The vibration waves sent across the water pipes causes them to start rattling, knocking against themselves as well as nearby objects.

Securing loose water pipes can be a simple or more complex activity depending on where the problematic pipes are located.

If the water pipes are in an accessible place like the basement or crawl space, you will only need to tighten the studs or brackets and your pipe will be quiet again. Water pipes running through the wall are harder to secure.

The first thing you can do to silence water pipes running through a wall is to try and secure them from their points of entry and exit. To do that, wedge in damping material like foam sleeves from both where the pipe enters and exits the wall.

Another thing you can is to secure them using insulation form spray. Drill a ½ inch hole on both sides of the pipes’ wall studs. Spray the insulation foam in the opening, and after about 1 hour the foam will expand and harden, thereby locking the pipes in place.

5. Insulate the Water Pipes

Another thing you can do is to insulate you water pipes with a damping material. This will drastically reduce the noise even when the pipes rattle and bang against each other and the nearest objects.

Foam tubes/sleeves are a good example to use. These are the sleeve foams used to cushion water pipes from freezing during winter.

Foam sleeves on their own are not sufficient to stop water hammers. They are ideally used in combination with other methods like water hammer arrestors and lowering the water pressure flowing to your house.

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