How to Install a Water Hammer Arrester

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Clattering pipes can be a major annoyance, but they also should alert you of a problem with the supply system.

 

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Continue to Step 1

Overview

Pipes can make a loud banging noise when faucets are turned off or when valves on washing machines (or other automatic appliances) shut abruptly. The sudden stop of flowing water traps air and creates a shock wave, called water hammer, that slams through the water supply system. Some pipes may knock against wall studs or joists, creating additional noise.
Water hammer can be more than an annoyance. The shockwave can cause damage and eventually failure in pipes and fittings. If a pressure-relief valve on your water heater leaks, it may not be a faulty valve, but a pressure surge in the supply system.
You can eliminate water hammer by installing a simple device called a water hammer arrester in the supply line. Inexpensive point-of-use arresters are small enough to be installed easily near the noisy valve or appliance (the closer the better). They can be positioned horizontally or vertically or at an angle without any change in effectiveness. Unlike with old-style air chambers, water cannot fill a water hammer arrester, so they should be effective for the life of the system.
Pipes that bang against studs or joists can be quieted by cushioning them with pieces of pipe insulation. Make sure pipe hangers are snug and that pipes are well supported.
From: The Complete Guide to Plumbing, 978-1-58923-378-2

What You'll Need

Tools:

Reciprocating saw or hacksaw
Propane torch (for sweating copper)
Pipe wrenches (for galvanized iron)
Adjustable wrench
Foam rubber pipe insulation
Pipe and fittings, as needed
Utility knife
Teflon tape

Materials:

Reciprocating saw or hacksaw
Propane torch (for sweating copper)
Pipe wrenches (for galvanized iron)
Adjustable wrench
Foam rubber pipe insulation
Pipe and fittings, as needed
Utility knife
Teflon tape

 

Step 1

How to Install a Water Hammer Arrester - Step 1

Shut off the water supply and drain the pipes. Measure and cut out a section of horizontal pipe for a T-fitting.


Step 2

How to Install a Water Hammer Arrester - Step 2

Install a T-fitting as close to the valve as possible.


Step 3

How to Install a Water Hammer Arrester

Install a short piece of pipe in the branch arm of the T-fitting. This short pipe will be used to attach a threaded fitting.


Step 4

How to Install a Water Hammer Arrester - Step 4

Install a threaded fitting. Use a fitting recommended by the manufacturer of your arrester.


Step 5

How to Install a Water Hammer Arrester - Step 5

Wrap the threads of the arrester in Teflon tape. Thread the arrester onto the fitting by hand. Tighten by holding the fitting with one adjustable wrench and turning the arrester with the other. Do not overtighten. Turn the water on and check for leaks.


 
 

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