What is water hammer and how do I fix it?

Water hammer in a shower valve is a phenomenon characterized by a sudden and loud banging or hammering noise that occurs within the plumbing system. This noise is a result of an imbalance of pressure in hot and cold water supply, typically caused by various factors within the shower valve. Here's a more detailed explanation of how water hammer occurs in a shower valve and how it can be resolved:

Balancing Pressure with Service Stops

Inside a shower valve, there are service stops that are designed to control and balance the flow of hot and cold water. These service stops regulate the amount of water flowing from the hot and cold water supplies into the shower, ensuring that the temperature and pressure are properly balanced. When these service stops are functioning correctly, they maintain equilibrium in the water pressure.

Debris Buildup

Over time, debris such as mineral deposits, rust, or sediment from the water supply can accumulate in the service stops. This buildup can obstruct the flow of water through the stops, causing a disruption in the balance of pressure between the hot and cold water supplies. As a result, the water flow becomes erratic and may lead to water hammer.

Imbalance of Pressure

When the debris obstructs the service stops, it can either restrict the flow of water or allow too much water to pass through one side (hot or cold), creating an imbalance of pressure within the plumbing system. This pressure imbalance can cause sudden and forceful water movements within the pipes, resulting in the characteristic banging or hammering noise known as water hammer.

To resolve water hammer issues in a shower valve, follow these steps:

Shut off the Water: Turn off the water supply to the shower to prevent any further water flow.

Inspect the Service Stops: Remove and examine the service stops to identify any visible debris or buildup. It's crucial to ensure they are clean and free from obstructions.

Cleaning with White Vinegar: If you find debris, remove the service stops and soak them in white vinegar for 12-24 hours. Vinegar helps dissolve mineral deposits and other accumulated debris. After soaking, rinse them thoroughly to remove any remaining residue.

Reinstallation or Replacement: Once the service stops are clean, reinstall them into the shower valve. Make sure they are tightly secured. If the service stops are damaged or cleaning doesn't resolve the issue, consider replacing them with new ones.

Turn Water Supply Back On: Finally, turn the water supply back on and test the shower to ensure the water flow is balanced, and there is no more water hammer noise.

Regular maintenance and cleaning of your shower valve's service stops can help prevent water hammer issues and ensure proper water pressure and temperature control in your shower.