water hammer

[fred1949]

Which is better to stop water hammer. I can either build one out of copper pipe or buy one at Lowes that has a valve in it. Which is better & which does the better job?

Fred

[LazyPup]

Technically speaking, its 6 of one and half a dozen of the other. There is one argument that the commercial water hammer arrestors have a rubber bladder separating the air from the water so the air cannot be absorbed into the water as it might in a field constructed vertical stub hammer arrestor but on the other hand, the rubber will deteriorate in 5 to 10 years, which then leaves you with a vertical stub.

The codes now require that an auxillary water hammer arrestor must be placed in the near proximity of all fast acting valves. Some examples of fast acting valves are solenoid operated water valves such as found on washing machines, dishwashers, steam or hydronic heating systems and some irrigation systems as well as float activated valves such as the toilet fill valve.

For new construction I prefer to use both methods. When making the stub outs for the bathroom lavatory I install a Tee with the side opening to the angle stop. Off the top on the tee I install an 18" vertical riser with a cap on top. These are fully contained inside the wall.

With the exception of the toilet fill valve line, I then install the small 6" auxillary hammer arrestors on the lines supplying the fast acting valves. (The hammer arresters on the lav are in the near proximity of the toilet valve so it meets code.)

[fred1949]

Thanks again for the info. You may make a plumber out of me yet.

Fred