Water Hammer

I am installing a shower and need to know if I should install air chambers to deal with water hammer. The water source is going to run past the shower valve body as shown below so I thought it might not be needed.



thanks

No, forget the air chambers. If the valve requires hammer arresters, put in some real ones that will work long-term. An air chamber like that eventually gets all of the air absorbed into the water flow and then do nothing. A proper hammer arrestor has a piston or bladder that separates the trapped air from the water.

What happens when the seal starts to leak or the bladder gets a hole in it. The nice thing about putting a tee in with a piece of pipe and a cap is when the air does get absorbed all you need to do is turn the water off and open the valve to refill it with air. If its one of the new and better hammer arresters with a bladder or piston when it fails, and it will, there is no way to repair it without tearing open the wall or if you are lucky and you have a access panel and then all you need to do is sweat in a new one

Air chambers are the way to go. If and when they do get filled with water, you shut down the system, open all the valves in the home and drain it down. Then slowly turn the water on. Now in the 20+ years I been doing plumbing I only had to do that twice in my lifetime. Most water hammer calls I get are due to no air chambers where installed.

Are air chambers used in PEX systems, too¿

SewerRatz said:

Air chambers are the way to go. If and when they do get filled with water, you shut down the system, open all the valves in the home and drain it down. Then slowly turn the water on. Now in the 20+ years I been doing plumbing I only had to do that twice in my lifetime. Most water hammer calls I get are due to no air chambers where installed.

Click to expand...

They fill up a lot quicker than you think they do...
Chances are if you think they were ding such a graet job at preventing water hammer they were not really needed at that location anyway...
Cuz they don't work...

Redwood said:

Cuz they don't work...

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Say it ain't so. SewerRatz, tell him it ain't so!

air chamber

quote; The nice thing about putting a tee in with a piece of pipe and a cap is when the air does get absorbed all you need to do is turn the water off and open the valve to refill it with air.

That MAY work, IF you can get ALL the water out of the system so air can get to the air chamber, AND you can figure out how to break the vacuum at the top of the air chamber so the water will drain out while air fills it. Do that and you may qualify as a genius. Even water heaters need to have air admitted into the top so they will drain. An air chamber is a much smaller version and needs even more help.

Redwood said:

They fill up a lot quicker than you think they do...
Chances are if you think they were ding such a graet job at preventing water hammer they were not really needed at that location anyway...
Cuz they don't work...

Click to expand...

Here in Illinois its in our code that we must install air chambers or device that meets the code. At the fixtures they are required to be 12" in length and the same size as the piping suppling the fixture. Then on Risers it needs to be 24" in length and same size as the riser. Now lots of the local codes do not allow for the mechanical or bladder type arrestors. The Illinois code is minimum requirements other localities can make it stricter. The cities that do allow the mechanical or bladder types also have in the code that they must be installed in such a way for them to be able to be serviced in the future. for example an access panel.

f) Water Hammer. All building water supply systems shall be provided with air chambers or approved mechanical devices or water hammer arrestors to absorb high pressures. Water pressure absorbers shall be installed at the ends of long pipe runs and near batteries of fixtures.