# Hammer arrestor



## Bill (Jun 17, 2008)

Does anyone here think it is needed on a house that has a private well??
I mean, a private well has to have an air ballast tank which in my opinion should be able to absorb the shock as well as an arrestor. 

Thoughts??


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## Plumbworker (Oct 23, 2008)

i've never plumbed anything on a private well..?:blink: i dont think it would hurt though


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## super plumber (Oct 19, 2008)

i agree with u bill the pressure tank should act as a big arrestor. i work in a rural area with many homes on wells and have not had any issues with water hammer. also the water pressure is normally lower on a well system than city water


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## Bill (Jun 17, 2008)

super plumber said:


> i agree with u bill the pressure tank should act as a big arrestor. i work in a rural area with many homes on wells and have not had any issues with water hammer. also the water pressure is normally lower on a well system than city water


Thats what I was thinking. I have been to the city where we had to install a pressure reducer. But a private well is usually only 60 lbs anyways and the bladder unless there is a check valve should suffice.


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## pzmember (Sep 20, 2008)

as long as there is not any kind of check valve between the tank and the house.


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## Redwood (Sep 8, 2008)

A hammer arrestor is geared more for a point of use application.
Think of the pressure tank more as the water main in the street.
You have a column of water in the pipe running at high velocity towards the filling washing machine when all of a sudden the valve closes because the machine is full. You still have all the momentum of that moving column of water between the pressure tank and the washer coming to a screeching halt. The energy needs to be absorbed at the point of use to be effective so yes you still need hammer arrestors at the washer.

The one thing that may save you from needing them is the fact that well systems usually run at a lower pressure so velocities in the pipe may not be as high.

But the pressure tank is not doing anything to absorb the effects of water hammer.


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## muck (Oct 10, 2008)

Bill said:


> a private well is usually only 60 lbs anyways and the bladder unless there is a check valve should suffice.


 Ya I agree with you here


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## 422 plumber (Jul 31, 2008)

If you the smallest pipe you run is 3/4" copper, you don't need air chambers, that's not code, just my experience.


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## Wethead (Oct 13, 2008)

Its always good to have a hammer arrestor


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## rocksteady (Oct 8, 2008)

i'm thinking if there were a case where a hammer arrestor would be beneficial, such as a fast closing washing machine, the well pressure tank would be too far away to serve the same purpose. with the lower pressures that well systems run at, i don't think you'd run into that problem often. i work on a lot of homes that have wells and i can't remember an instance of needing an arrestor. city water, that's another story. the next town over has pressures over 150psi in some places.






paul


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## Proud Plumber (Sep 15, 2008)

Redwood said:


> A hammer arrestor is geared more for a point of use application.
> Think of the pressure tank more as the water main in the street.
> You have a column of water in the pipe running at high velocity towards the filling washing machine when all of a sudden the valve closes because the machine is full. You still have all the momentum of that moving column of water between the pressure tank and the washer coming to a screeching halt. The energy needs to be absorbed at the point of use to be effective so yes you still need hammer arrestors at the washer.
> 
> ...


We are required to install washer boxes and ice maker boxes with shock arrestors on them. All quick closing valves are required to have shock arrestors on them.


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## Redwood (Sep 8, 2008)

rocksteady said:


> i'm thinking if there were a case where a hammer arrestor would be beneficial, such as a fast closing washing machine, the well pressure tank would be too far away to serve the same purpose.


Exactly! its on the wrong side of the water supply. It would be the equivelent of puting a large hammer arrestor on the cities water tower base and saying it would protect the whole town. The problem is there might just be a few miles of water moving through the pipe that have the momentum that causes the water hammer.

Of course in a home the distance would be less but the principle is the same.


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## celtic1 (Dec 16, 2008)

*Yes do it, in My opinion*

Some homes on wells, get city water at a later date. Walls are all closed in then! It's in My code. 12" risers for 1/2" and 18" for 3/4"


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## Redwood (Sep 8, 2008)

celtic1 said:


> Some homes on wells, get city water at a later date. Walls are all closed in then! It's in My code. 12" risers for 1/2" and 18" for 3/4"


Your code is outdated in its practices.
It is widely accepted that the traditional "Air Chamber" does not work for long as they rapidly fill with water and then fail to provide any cushion at all. Only the use of a Hammer Arrestor that uses a piston to provide a seal between the water and the air charge will work in the long term. Installing the traditional risers is a waste of copper.


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## ROCKSTARPLUMBER (Dec 14, 2008)

Our code requires them on the washing machine, ice maker boxes, and the hot side of the kitchen sink, for dishwahser. had to install one the other day for a customer, pipe was slamming in the ceiling of their bedroom when they ran the dishwasher at night. Was on a well too. 60lbs of pressure.


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## celtic1 (Dec 16, 2008)

*No arguement there!*



Redwood said:


> Your code is outdated in its practices.
> It is widely accepted that the traditional "Air Chamber" does not work for long as they rapidly fill with water and then fail to provide any cushion at all. Only the use of a Hammer Arrestor that uses a piston to provide a seal]
> 
> Next time in the Bay area have a sitdown with the 30 or so plumbing inspectors. My self ,I like My jobs signed off! S.F. Has many amendments to the U.P. C. One is all roof drainage,and area drains to the lateral! gas drip legs every 90 degrees! BLA BLA BLA. I don't like it ,but I like to EAT!
> Ps You're 100% right on air chambers! :yes:


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