Which tool should I use to avoid a water hammer

Which Tool Should I Use to Avoid a Water Hammer? Understanding Your Options

You've probably heard that banging sound when you shut off a faucet quickly, or when a washing machine or dishwasher suddenly stops. That's the sound of water hammer, and while it might seem like a minor annoyance, it can actually cause significant damage to your plumbing system over time. But don't worry, there are several effective tools and solutions to prevent this jarring phenomenon. This article will guide you through the best options for avoiding water hammer.

What Exactly is Water Hammer?

Before we dive into the tools, let's quickly define water hammer. Also known as hydraulic shock, water hammer occurs when a fast-moving column of water is suddenly stopped or its direction is changed. This rapid deceleration creates a pressure wave that travels through the pipes, causing them to vibrate and bang against walls or other structures. Think of it like a shockwave through your water lines.

Common Causes of Water Hammer

• Quickly closing valves: This is the most frequent culprit. Faucets, solenoid valves in appliances (like washing machines, dishwashers, ice makers), and even toilet fill valves can shut off water flow very abruptly.
• Failing pressure reducing valves (PRVs): If your home's water pressure is too high, a PRV is installed to regulate it. A faulty PRV can allow pressure surges that lead to water hammer.
• Air in the system: While it might seem counterintuitive, air can sometimes contribute to water hammer by creating pockets that can collapse suddenly.
• High water pressure: Homes with excessively high municipal water pressure are more susceptible.

The "Tools" You Need to Avoid Water Hammer

When we talk about "tools" to avoid water hammer, we're not usually talking about a single hammer you swing. Instead, we're referring to plumbing devices or techniques that absorb the shock. The most common and effective solution is the installation of water hammer arrestors.

Water Hammer Arrestors: The Primary Solution

A water hammer arrestor is a small device that acts as a shock absorber for your plumbing system. It works by containing a cushion of air or gas that can compress when the water pressure surge occurs, thereby dissipating the shockwave.

Types of Water Hammer Arrestors

There are a couple of main types of water hammer arrestors you'll encounter:

1. Piston Type Arrestors: These are the most common and generally considered the most durable. They consist of a cylindrical chamber with a piston that moves freely inside. One side of the piston is exposed to the water, and the other side is sealed with a cushion of air or gas. When a pressure surge occurs, the water pushes against the piston, compressing the air/gas cushion and absorbing the shock.
   • How they work: When a valve closes suddenly, the water behind it slams into the piston. This piston then moves into the chamber, compressing the trapped air and absorbing the kinetic energy of the moving water. As the pressure equalizes, the piston returns to its original position.
   • Where to install them: Piston arrestors are typically installed directly onto the water supply line, close to the appliance or fixture that is causing the water hammer. For washing machines, they are often installed right at the hot and cold water hookups. For faucets, they can be installed under the sink.
   • Advantages: They are very effective, relatively compact, and designed to withstand the constant pressure of a water system. They are also less prone to losing their air cushion over time compared to older types.
2. Air Chamber Arrestors (older style): These are essentially vertical pipes or chambers attached to the water line that are partially filled with air. The idea is that the air trapped at the top of the chamber will compress when a water surge occurs.
   • How they work: When a sudden surge of water occurs, it pushes into the air chamber, compressing the air. This compression absorbs the shock.
   • Disadvantages: The primary drawback of air chamber arrestors is that the air can be absorbed into the water over time, rendering them ineffective. They often need to be "recharged" by draining the water from the line to let air back in, which is a more labor-intensive process. Many modern plumbing codes discourage their use due to this issue.
   • Recommendation: For most homeowners, the piston-type arrestors are the superior choice due to their reliability and lower maintenance.

Other Important Considerations and "Tools"

While water hammer arrestors are the primary "tool" for direct shock absorption, other factors and simple fixes can also contribute to preventing or reducing water hammer:

• Securing Pipes: Sometimes, the banging you hear isn't just the water itself, but the pipes rattling against joists or walls.
  • Tool: Pipe straps or clamps.
  • How to use them: Ensure all exposed water pipes are securely fastened to the framing of your house with appropriate pipe straps. This will prevent them from vibrating excessively and making noise.
• Addressing High Water Pressure: If your home's overall water pressure is too high, it's a major contributor to water hammer.
  • Tool: Pressure Reducing Valve (PRV).
  • How to use it: A PRV is a device installed on your main water line where it enters your house. It reduces and regulates the incoming water pressure to a safe and consistent level (typically between 40-60 psi). If you suspect high water pressure, you can test it with a simple water pressure gauge that screws onto an outdoor faucet. If the pressure is consistently above 60 psi, a PRV is a wise investment.
• Slow-Closing Valves: For faucets that don't have a solenoid valve (like standard bathroom or kitchen faucets), you can consciously train yourself to close them more gently.
  • Tool: Patience and good habits!
  • How to use it: Simply turn off the faucet with a smooth, deliberate motion rather than a quick snap. This is the simplest and cheapest method for manual faucets.
• Checking Appliance Valves: The solenoid valves in appliances are often the biggest culprits.
  • Tool: Water hammer arrestors (as described above) are crucial here.
  • How to use them: Install arrestors on the hot and cold water lines feeding your washing machine, dishwasher, ice maker, or any other appliance with quick-shutoff valves.

Which Tool is Right for You?

For most homeowners experiencing water hammer, the primary "tool" to consider is the piston-type water hammer arrestor. They are effective, relatively inexpensive, and easy to install for anyone with basic DIY plumbing knowledge (or a plumber can do it quickly).

If you have consistently high water pressure throughout your home, addressing that with a Pressure Reducing Valve (PRV) is a fundamental step that will benefit your entire plumbing system and help prevent water hammer at its source.

For older homes where pipes might be loose, simply using pipe straps can eliminate the banging sounds even if the pressure surges are minor.

When to Call a Professional

While installing a water hammer arrestor can be a DIY project, if you're uncomfortable working with plumbing, have a complex system, or suspect issues with your main water pressure, it's always best to call a qualified plumber. They can diagnose the exact cause of your water hammer and recommend and install the most appropriate solution for your specific situation.

Frequently Asked Questions (FAQ)

How do I know if I have water hammer?

You'll know you have water hammer if you hear a loud banging, thumping, or rattling noise in your pipes, particularly when a faucet is suddenly turned off, or when an appliance like a washing machine or dishwasher finishes its cycle and shuts off its water supply.

Why is water hammer bad for my pipes?

Water hammer creates intense pressure surges that repeatedly jolt your plumbing system. Over time, this can weaken pipe joints, loosen fittings, damage valve seats, and even cause leaks or burst pipes. It's like repeatedly slamming a door shut – eventually, something will break.

How do I install a water hammer arrestor?

For most piston-type arrestors, installation is straightforward. You'll typically shut off the main water supply to your home, drain the line, and then screw the arrestor onto the threaded outlet of the valve where the appliance or fixture connects. Many come with clear instructions. If you're not comfortable with this, a plumber can install them quickly.

Can I just ignore water hammer?

While it might be tempting to ignore the noise, it's not recommended. Water hammer is a sign of stress on your plumbing system. Continuing to ignore it can lead to more serious and expensive repairs down the line, such as leaks, burst pipes, or damage to your appliances.

Are there any permanent solutions for water hammer?

Water hammer arrestors, especially piston-type ones, are considered a long-term solution. They are designed to last for many years and require little to no maintenance. Addressing high water pressure with a PRV is also a permanent solution for that specific contributing factor.