How to Fix the Water Hammer Problem in Your Plumbing
(updated 2020)

PlumbingImage by 5317367 (Pixabay)

Water hammer is the most common home plumbing problem that can be recognized as pounding, banging and thumping noise and pipe vibration. While it is quite annoying, it can also be a serious problem affecting your water heater performance and safety.

In order to properly deal with this issue, check out this troubleshooting guide and learn about the causes, symptoms, how to prevent and get rid of water hammer fast and easy.

Is the water hammer a big problem and can it be fixed

An issue will occur when water is moving through the plumbing and the outlet valve is suddenly stopped, resulting in vibration along the pipeline. Due to sudden pressure change and the shock waves, pipes will usually hit against the house's framing, creating a banging or thumping noise.

As the water movement stops abruptly, the high-intensity pressure wave is created, traveling back and forth between the point of relief and point where the stop is, until it dissipates in the plumbing system.

Note: No matter whether you live in a new or old house, the water hammer can happen anywhere and anytime.

A problem is not only with the banging and irritating noise, but its destructive nature for plumbing, fittings and your heating unit. The pressure created in plumbing can go over 60 times.

For other noise related issues, check out this repair guide.

As we mentioned before, the excessive pressure builds-up in the plumbing system and goes from the pipeline into the tank, where permanent deformation might occur. Usually, the tank shell will expand, and by measuring the circumference at various locations along the tank, you can see how serious it is.

When the water hammer occurs, high pressure in the heating system and pipes banging against the framing members can cause the unstable plumbing system.

For example, the flue tube installed on a gas water heater on one side, and through the wall on the other, might collapse. With the deformed vent, flue gases won't be able to find the way out, causing the flame and gas combustion to spill out from the combustion chamber.

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How to repair a water hammer and prevention tips

The solution for the problem is in installing a water hammer arrestor (which is sometimes required by the local code), such as this Sharkbite or this model from Watts.

The element is also known as the air chamber and it is designed to work similar to expansion tanks, with a diaphragm that separates an air chamber from the water in the plumbing system. The air works as a cushion, absorbing the shock wave from the excessive pressure.

What you should identify is the source of the shock wave so you can install the arrestor close to that point.

Other solutions might be to install an expansion tank or pressure only relief valve that works as a sacrificial valve when working with abnormal pressures.

Installation tips

As explained, the water hammer arrestor should be installed close to the appliance, fixture or fittings that is causing the issue. The installation is as simple as installing any of the fittings. When dealing with the copper pipes, you can either solder to the pipe, or buy a water heater arrestor with the compression fittings.

Now. .. about the noise

A common question from consumers is: My water heater makes the popping noise? Is that a water hammer, noisy pipes or something else?

Plumbing is not always "guilty" for all kind of noises that you can hear when running a heater, washing machine or dishwasher.

The rattling sound might come from a defective seat washer, even when the tap is barely open.

Moaning or chattering sound may be caused by the high pressure.

Ticking noise occurs when you open a hot tap, and hot water suddenly runs through the cool hot water pipe. It might also be that a copper pipe expands due to the high water temperature.

The common cause of ticking noise and water hammer is if your sink or shower/tub is using a single lever faucet or due to dishwasher and washing machines' automatic solenoid valves. Sometimes a simple change of a defected seat washer is the solution. More info about water heater noise find here.

Conclusion

There are several approaches in how to prevent and repair the water hammer problem, where the noise and vibration are the main issues that has to be eliminate. Designing the plumbing pipes properly, and replacing the undersized pipes with the larger ones are the way to go if possible. For the existing plumbing system, wrapping the insulation around the pipes might be sufficient to minimize the rattling noise, also securing the loose ones. Or simply installing the water hammer arrestor.

This is a fairly simple DIY project.

Note: If there is damage to a tank heater due to water hammer, the manufacturer is not eligible for warranty compensation.

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