There are are three factors that contribute to noises in the water supply system.
Water hammer– is the shock, and accompanying banging noise, created when a valve or faucet is suddenly closed against water flow.
Vibration hammer– Caused by hammer that has loosened pipe hangers supports or where never installed in the first place.
Rushing noises– Noises of rushing and turbulence can be reduced by reducing the velocity of the flow in the pipe. Also, the type of fitting or valve may be changed so that the change of direction is less abrupt.
( Various means are available to reduce velocity while maintaining the rate of flow. By increasing the pipe size or by substituting pipe bends with 90 degree elbows, by using pipe increasers instead of pipe bushings, and by changing the style or make of valve. Valves and fittings vary in quality as do all other types of merchandise. Poor quality usually means poor or faulty design, rough interiors, abrupt changes in direction , and possibly actual reduction of the water way through the device. The old saying “you get what you pay for” is as true of plumbing as it is of other merchandise).
Fixes- To prevent water hammer the use of mechanical shock absorbers in appropriate locations on the water supply system is your first step. In most cases replacing a bad water hammer arrestor solves the problem of banging noises and rattling in the ceiling or walls of homes and commercial facilities.
There are different styles and shapes of engineered devices on the market place. While the basic principle of operation in each unit is somewhat different, each unit is designed with a permanent cushion of gas or air to offer the displacement needed to control shock.
Before you begin to replace potential malfunctioning shock absorbers you need to check water pressure. The International Plumbing code recommends no more than 80 PSI of water pressure.
Adjust your water pressure regulator accordingly to 80 PSI insuring you use the proper Pressure regulator that either has a strainer with the device or you install a strainer before the (PRV). See pictures.
Make adjustments to your pressure regulator valve by loosing the lock nut and turn the top bolt clock-wise for increase of pressure and counter-clockwise for decrease of water pressure. Its much easier if you use a buddy system ( two people working together) if you don’t have a pressure gauge to look at while your making your adjustments. Check your water gage either outside on a wall hydrant like the picture shows,or connect your gauge to any fixture were you can get and maintain a constant pressure. If you are not getting a constant water pressure at the gauge you probably have a bad PRV and will need to replace it before you can go any further on determining what is causing water hammer.
After you have made adjustments to your PRV your ready to trouble shoot the rest of the house or building.
Listen to where the trouble started and find out if you still have a problem.
All fixtures have the potential to cause water hammer, what has to be determined after insuring you have the proper water pressure is if your still getting banging, hammer sound, rushing water.
Depending when your home or building was built you will need to take a look to see if you have a mechanical shock absorber like the ones in the following pictures. No matter what style of mechanical shock absorber you have the water hammer arrestor requires it to be to near the fixture it is serving to work properly. If the banging noise is at the fixture you will need to replace it. If the water hammer arrestor like I have seen in commercial projects is not close enough to the fixture or fixtures it is serving you will have to relocate it.
Other potential problems that you will have to pay attention too are your fixtures themselves. All quick closing fixtures can cause water hammer. After you have adjusted your water pressure, replaced faulty water hammer arrestors, tightened up pipes in the wall and secured your pipes in the ceiling and you still have problems with banging the next step is to isolated the fixture and either rebuild the fixture or replace it.
I have seen where a faucet was repaired and when the parts where put back in they were either loose or the wrong washer were put in, causing squeaking noises and water hammer.
In homes by following the above procedures 99% of the time you can fix the problems yourself. If you have a more complex plumbing installation like a swimming pool, solar system, or other appliances connected to your water system, trouble shooting may be a little more complex. Example: you may have a air tank that has become water logged, or a solenoid valve that needs to rebuilt. Either way trouble shooting begins with water pressure.
For further information on a variety of plumbing maintenance issues you can find my book at Amazon.com called “Flush Your Plumbing Troubles Down The Toilet”.