# where to install water hammer arresters ?



## amakarevic (Apr 12, 2007)

also, which arresters should we get, considering the intensity of the problem (heard in the whole house) ? i am thinking it may be worth to shell out a few more $$ and get decent ones from ferguson or some place rather than go with the nipple-looking ones from HD ...


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## 47_47 (Sep 11, 2007)

Water hammer is usually caused by the closing of electric solenoid valves as found on washing machines, dishwashers... They are most effective when installed at the device.

If all the faucets hammer, your water pressure may be too high.


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## Termite (Apr 13, 2008)

Yes, fast-acting valves will usually be the culprit. The arresters should be placed right at the washing machine valves...Washing machines are often the biggest problem area.

Agreed, a pressure reduction may be in order if operation of the sinks and showers causes hammering.


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## amakarevic (Apr 12, 2007)

thekctermite said:


> Agreed, a pressure reduction may be in order if operation of the sinks and showers causes hammering.


okay then, we will slap a couple of nipple-looking arresters above the washer valves.

if the high pressure turns out to be the issue, should we get a bell-shaped pressure reducer at the entry point into the house like the one i happen to have before the pipe goes into my radiator boiler ?


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## majakdragon (Sep 16, 2006)

Most arrestors I have installed were located in the inlet and outlet piping at the water heater. It kept them accessable and easy to change if something happened to them. When I worked in Florida, the code required an 8" extension above each fixtures supply piping (except the kitchen sink) which was the same size as the supply piping and a cap on the end. This is what they considered hammer arrestors. I will say, Florida had some weird codes.


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## 47_47 (Sep 11, 2007)

majakdragon said:


> Most arrestors I have installed were located in the inlet and outlet piping at the water heater. It kept them accessable and easy to change if something happened to them.


A question majakdragon, I could see the use of one on the outlet side of a water heater, but the inlet is usually teed off of the main branch. What purpose would one on the cold side serve?


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## majakdragon (Sep 16, 2006)

Since we did almost all one story homes, the water heater piping was the highest point on the waterlines. Having one on the cold water inlet also served the rest of the houses cold water feeds. We always fed the water heater first off of the main line. The reason the code called for these was to prevent water hammer caused by air in the lines. (not for quick shut-offs from appliances)


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## Termite (Apr 13, 2008)

In all my years, I've never seen anyone put hammer arrestors at a water heater. It just doesn't make any sense, no matter how the plumbing is configured. There is no potential for water hammer unless there is an abrupt interruption of flow...That does not happen at a water heater. Putting a hammer arrestor way upstream of a fast acting valve will not be as effective as locating it right by the valve.

Some old school guys will put air chamber (simply pipe stubs intended to be full of air) arrestors by shower valves and other fixtures. They inevitably fill with water in no time, and are a simple waste of time and pipe. The only way to go are the ones like Sioux Chief makes.


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## majakdragon (Sep 16, 2006)

thekctermite, as strange as you may think it is, it is code in Florida to put air chambers at each fixture except the kitchen sink. I have also seen water hammer with no "fast acting" valve being operated at the time. In many of the Forums I post in, the person asking about the noise states it happens with a bathroom sink or even a toilet when flushed. They always describe it as "the pipes in the wall are vibrating". Strange things happen in plumbing and I cannot explain them all. I just do what I can.


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## mstplumber (May 3, 2008)

Sioux Chief makes a wide variety of water hammer arrestors, many of which can be installed in a retro-fit application. They also have a pretty good FAQ about water hammer. Here's the link:
http://www.siouxchief.com/Frm_NS.cfm

Hope this helps.


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