Stopping Water Hammer Noise in Pipes
Knocking and thumping sounds in your walls or basement when the clothes washer fills or during the rinse cycle often indicate a condition called water hammer. Here’s how to diagnose and fix this issue:
Understanding Water Hammer
- Symptoms: Knocking or thumping sounds when the clothes washer fills, during the rinse cycle, after a toilet fills, or when a faucet is quickly turned off.
- Cause: Water is heavy and carries a lot of energy as it moves through pipes. When a valve quickly stops the water flow, the energy shakes the pipes against the home’s framing. This is especially common with fast-closing valves in washing machines.
The Solution: Water Hammer Arresters
- Function: A water hammer arrester provides an air cushion that compresses when water flow is suddenly stopped.
- Benefit: The air cushion absorbs the energy, preventing the pipes from hammering.
Types of Water Hammer Arresters
- Modern Arresters: Sealed units that should never lose their air cushion, requiring no maintenance.
- Older Arresters: Inverted, capped pipes intended to be filled with air. These can lose their air cushion over time.
- Re-establishing Air Cushion: If older arresters lose their air cushion, you need to drain the plumbing system to re-establish it.
Summary: Water Hammer Noises and How to Fix
Water hammer causes pipes to knock due to the energy of moving water being stopped abruptly. The fix is to install water hammer arresters, which provide an air cushion to absorb this energy. Modern arresters are sealed and maintenance-free, while older types may need occasional draining to restore their air cushion.