Have you ever heard a banging in your walls when you or another person turns off the water at the sink or tub? The sound can be unnerving and may lead to damage to your home. A water hammer may, over time, lead to a leak or burst pipe in your home.
When HomePro Inspections performs a home inspection, our home inspectors listen for clues of a potential water hammer as we operate water valves in a home.
What is water hammering?
Water hammering is the result of a surge of pressure when a water valve is closed suddenly. Water does not compress, so when a valve is closed, the flow is stopped instantly. It’s kind of like walking into a wall.
A sudden stop in a water line can generate pressure up to three times that of the water flow pressure. That pressure can cause pipes to move, displace, or vibrate within your walls. Over time, that spike in water pressure may cause a leak or burst a pipe, causing water damage over an extended period of time or all at once. Fortunately, a water hammer can be fixed.
Split water line
This video from “Practical Engineering” does a really good job of explaining what a water hammer is.
What causes a water hammer?
There are several factors that can cause or contribute to a water hammer. One or more of these could be causing the banging in your walls.
Water Pressure – High water pressure is one potential cause of a water hammer. The higher the pressure of the flow of the water, the higher the pressure when that flow is suddenly stopped at a valve.
Appliances – Appliances that use water, such as a washing machine, dish washer, and even the water dispenser/ice maker on the refrigerator, can cause a water hammer. The water valves on these types of appliances shut off quickly.
Watch the flexible water supply hoses on the washing machine or the coil of copper at the back of your refrigerator when the water is shut off. The flexibility in these lines helps to absorb some of the energy, but they can still shake, move, or wiggle quite a bit when the valve is shut off.
Loose Pipes – Having some flexibility in the water lines in your home can help with dampening a water hammer’s energy. If they are in contact with your walls or structure, you may hear banging. Modern PEX water lines do a better job at dampening than rigid copper water lines. However, too much movement in rigid copper water lines may result in cracked solder joints and leakage. Long runs of copper water line with minimal support are prone to excessive movement.
Leaking joint at the elbow
Old Plumbing Systems – Because older water plumbing systems lack modern plumbing standards, they can be prone to water hammer. Sometimes, during a home inspection in an older home, our home inspectors will find bladder tanks and pressure relief valves in the water supply system. These devices will help to mitigate water hammering.
Fixing a water hammer
There are several possible solutions to eliminate a water hammer problem. Depending on the issues you may be having with your plumbing system, one or more of the following fixes may be needed to eliminate a water hammer in your plumbing system.
Water Pressure Regulators – Managing the water pressure within your plumbing
system with a water pressure regulator can prevent surges or higher water pressures.
Water Hammer Arrestors – These devices are installed in your plumbing system to absorb the shock in a water line when the flow suddenly stops due to the fast closing of a valve or faucet. Within the water hammer arrestor is basically a pocket of air or a bladder that will compress and absorb the higher water pressure when the water flow is suddenly stopped.
Below is a photo of a washing machine outlet box with water hammer arrestors integrated into the design. Washing machines, dishwashers, and refrigerators have valves that close quickly. Installing a water hammer arrestor in close proximity will eliminate a water hammer.
Water Hammer Arrestor
Air Chamber/Bladder Tank – These are not as common. Our home inspectors come across air chambers and bladder tanks in older homes as a retrofit to older plumbing systems. They provide extra space for expansion and absorption of water pressure changes.
Air Chamber/Bladder Tank
Pressure Relief Valves – These devices use an internal spring within the valve. Higher than normal water pressure will overcome the spring force and open the valve. Any water released can be routed to a drain.
Pressure Relief Valve
Loose Plumbing – Any loose plumbing should be secured to your home’s structure to keep it from banging. Although this may not be the root cause of the banging, securing pipes will help reduce the potential for cracking or loosening of any solder joints.
Summary
Water hammers are at the very least annoying, depending on their proximity and loudness. In a worst-case scenario, if a leak develops and goes undetected for a period of time, it can result in serious water damage.
At HomePro Inspections, our home inspectors are trained to inspect plumbing systems and identify any defects. Any issues are documented in your home inspection report and recommended for resolution by a qualified professional.
Visit our website to learn more or to schedule your home inspection in the Rochester, Owatonna, and Faribault, MN areas. You can contact us today at (507) 202-8942 or utilize our online “Schedule Now” feature to set up an appointment.