You can cure water hammer by turning off the water behind the flooded chamber, opening the offending tap, and allowing the faucet to drain completely. Once all the water is drained from the chamber, the air will refill it and restore the cushion. Remove the plumbing fixture where the water hammer is taking place. Trim drywall around water supply valves to access wall pipes.
Loosen the water supply valve coupler with an adjustable wrench, then slide the valve, ferrule, and coupler out of the copper tubing. Cut an 18-inch copper pipe that matches the diameter of the copper pipe from the wall with a pipe cutter. Clean the burrs on each end of the pipe, then apply flux to one end of the copper pipe and to the inside of a copper cap of the same diameter as the pipe. Weld the cap to the pipe with welding wire and torch.
All air chambers must be recharged with air from time to time or every time a water hammer occurs. You can do this by turning off the water and draining the pipes to let air in. Spread the pipe glue around one end of the 1-foot pipe section. Slide a tube cap over the end of the tube.
Spread the pipe glue around the other end of the pipe and around the inside of the male end of the reducer. Insert the tube into the reducer. The air chamber is now complete. Wait about half an hour for the glue to dry inside the pipe.
The water in the air chamber will also drain. With the water out, the chamber will fill with air. Turn off the faucet and open the shut-off valve to refill the line with water. It will be sprayed to remove excess air, but will trap air in the chamber.
The hammer should no longer be produced. You will need to do this for both the cold and heat supply lines. Water hammer, also called hydraulic shock, is “a concussion sound when moving water against the sides of a pipe or container,” (Illinois State Plumbing Code). Water hammer is the result of a rapid deceleration of water flow in an enclosed space, such as a pipe.
There are a few ways to solve this problem, which require simple parts and technical knowledge. A water hammer suppressor, for example, is a device used to absorb pressure increase when the flow of water suddenly stops. A device called an air chamber may be required instead of a mechanical water hammer suppressor. An air chamber is an extension of the water supply pipe near the pipe fitting that provides the air cushion to absorb hydraulic shock.
If you look at the image below, the pink lines you see are the real “air chambers”, while the other lines are the hot and cold water supply, and the drain and vent pipes. To recharge the inner tubes in a plumbing system, start by turning off the water in the water meter. Then open the tallest faucets first (the ones that are farthest from the meter) and then go down to the basement or utility room. When you turn on the laundry faucet, usually the lowest in the house, the whole house drains into the bathtub.
Don't forget to open the keys to the outer sill and pull the toilet chain on your way. To fill the chambers with air, you need to completely drain the water from your plumbing system. As the pipes drain, so does the water in the air chambers. The first step is to close the main water supply valve.
Then turn on all the faucets in the house and flush all the toilets. Turn on the lowest faucet (s) (hot and cold) in the house, or a drainage system, if you have one, and all the water will flow out of the pipes. Don't forget to turn on the washing machine (turn it hot to open the hot and cold valves) and the dishwasher for a few moments to make sure the pipes are also completely drained. It has fittings that screw onto a faucet, toilet, or appliance hose, and an air chamber made with a diaphragm or piston in a sealed chamber.