# where should i add hammer arrestors ?



## Bayside500 (May 16, 2009)

doing a shower with those digital kohler valves, 

i decided to test this before they dura rocked the walls, and when i shut off the hand held line it hammers really badly.

i didn't draw in the supply lines to the valve boxes, but they have 3/4" hammer arrestors on the feeds within about 2 feet of the boxes.

so where would be the best placement of arrestors on the 4 individual 1/2" lines to the heads ?


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## Redwood (Sep 8, 2008)

Before the valve


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## Bayside500 (May 16, 2009)

Redwood said:


> Before the valve


i have them before the valves on the 3/4" feeds, it is the 1/2" lines that go up and over to the opposite wall where the heads are that hammers when shut off.


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## Redwood (Sep 8, 2008)

How well are the pipes secured?

Not sure how a legitimate water hammer could be developed in an open ended pipe...


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## Gettinit (May 9, 2012)

They should be as close to the valve as possible. The further away it would be wise to increase it in size. I would gather all of your lengths of pipe, sizes and call the hammer arrestor manufacturer for the right size and placement if you don't want to play around.


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## MarkToo (Dec 17, 2011)

You aren't going to get water hammer at the outlets or shower heads. You may have pipes rattling around a bit because they aren't supported or installed quite right.

You need to reevaluate your install and pipe support downstream of the valves. Ensure they are secured properly.


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## TPWinc (May 30, 2011)

Bayside500 said:


> doing a shower with those digital kohler valves,
> 
> i decided to test this before they dura rocked the walls, and when i shut off the hand held line it hammers really badly.
> 
> ...


As close to the Hand held as possible. Assuming you are turning the water off at the HH. Did you test with the line capped? If so I bet it won't do it when the line are open. Unless the pipes are loose.


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## Gettinit (May 9, 2012)

If it is hammering while running it is usually a loose washer.


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## Redwood (Sep 8, 2008)

.....


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## SHAUN C (Feb 16, 2011)

Bayside500 said:


> doing a shower with those digital kohler valves,
> 
> i decided to test this before they dura rocked the walls, and when i shut off the hand held line it hammers really badly.
> 
> ...


Maybe the prv?


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## U666A (Dec 11, 2010)

Redwood said:


> .....


That how that works? :laughing:


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## UN1TED-WE-PLUMB (Oct 3, 2012)

Test water pressure. If it is too high then it will cause what your describing.


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## Protech (Sep 22, 2008)

Redwood said:


> How well are the pipes secured?
> 
> Not sure how a legitimate water hammer could be developed in an open ended pipe...


Water hammer can and will occur on an open ended pipe. Go hookup a 20' length of pex to a ball valve and slam it shut. It'll happen.


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## Redwood (Sep 8, 2008)

U666A said:


> That how that works? :laughing:


:laughing::laughing::laughing:

A few years back I was playing firefighter at a department drill one Sunday morning...

We has a couple of trucks tied in on one hydrant and we were flowing about 3000 gpm there, in the same block there were several other trucks set up and pumping prolly in the neighborhood of 5 - 6,000 gpm total...

When the new deputy chief running the drill decided to end the drill...

Instead of calling for gradual flow reductions and shut downs he just called out on the radio, "All Units Shut Down." 

I was running toward the pump panel yelling, "N-o-o-o-o-!" just in time to see both pump operators chop the throttle and close the valves....

There was a water hammer event... :yes::laughing:
Our incoming hoses held... But the main didn't...:laughing:


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## Protech (Sep 22, 2008)

Bayside500 said:


> i have them before the valves on the 3/4" feeds, it is the 1/2" lines that go up and over to the opposite wall where the heads are that hammers when shut off.


How many heads are being run on each 1/2" line? Sounds like to much velocity is a possibility.


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## UN1TED-WE-PLUMB (Oct 3, 2012)

Protech said:


> Water hammer can and will occur on an open ended pipe. Go hookup a 20' length of pex to a ball valve and slam it shut. It'll happen.


Especially with excessive water pressure. 

Just like a fluid master will cause a bang when it shuts off if the water pressure is over 80 psi or so.


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## Bayside500 (May 16, 2009)

Protech said:


> How many heads are being run on each 1/2" line? Sounds like to much velocity is a possibility.


4 total 1/2" lines, 1 line is for shower head, 1 line is for handheld, each of the other two 1/2" lines have 2 body sprays each.

each valve control box has two 1/2" outlets, so 1 valve box controls showerhead and handheld, the other box controls two sets of dual body sprays.


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## Bayside500 (May 16, 2009)

i will check the pressure but i doubt it is more than about 60lbs.


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## Protech (Sep 22, 2008)

Your valves are cavitating. Install an air chamber just after the valves on each line. A hammer arrestor WILL NOT WORK. It must be an air chamber.


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## Don The Plumber (Feb 14, 2010)

Protech said:


> Your valves are cavitating. Install an air chamber just after the valves on each line. A hammer arrestor WILL NOT WORK. It must be an air chamber.


 Just after the valves, means on the open ended pipe, correct?


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## Bayside500 (May 16, 2009)

yes it is the open ended line that is hammering, the valves are digitaly controlled by a keypad deal that goes on the wall at trim out stage.

and yes pipes are secured well.

everything is run in copper and when you shut off the valve controller, it makes a sharp tinking type of noise, just once in the 1/2" pipe, there is NO shut off on the hand held end.

i did have the shower head line capped while doing this, maybe if i leave both the shower head and hand held open like it will be in normal use it will not hammer ?

both the shower head and hand held come off the same digitally controlled valve box, but have separate 1/2" lines ran to them, and the controller can run either the shower head or hand held separately or both at the same time.

i will mess with it monday and report back.

i'm am just glad i thought to check for this before they dura rocked the walls, as no one in my shop has never installed one of these things before


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## OldSchool (Jan 30, 2010)

Sounds like your shower valve is a quick closing type ... That will give you water hammer no doubt ... Installing the right size of shock absorbers on the hot and cold lines at the valve should stop the problem ...

More than likely the vibration of the water hammer is just traveling along your open ended shower outlets ...


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## Widdershins (Feb 5, 2011)

Have you checked the solenoid(s) to be sure they are free of debris?


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## PLUMBER_BILL (Oct 23, 2009)

Bayside500 said:


> doing a shower with those digital kohler valves,
> 
> i decided to test this before they dura rocked the walls, and when i shut off the hand held line it hammers really badly. >snip<
> 
> ...


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## PLUMBER_BILL (Oct 23, 2009)

*more on water hammer*

When we were doing a lot of new work. Backflow valves were just starting to be used. Therm Tanks were required. We did not install those tanks at the water heater. We put them at the point of the water service entrance. We found out that all traces on water hammer ended.


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## MarkToo (Dec 17, 2011)

Was thinking about this...

If it's just the hand spray line as you said, check the connections as there's likely a vacuum breaker in line with it. Try it with and without. See if that gives you any ideas.


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## Bayside500 (May 16, 2009)

MarkToo said:


> Was thinking about this...
> 
> If it's just the hand spray line as you said, check the connections as there's likely a vacuum breaker in line with it. Try it with and without. See if that gives you any ideas.


actually, i just put a rough-in galvanized nipple in the wing ell and then an old boiler drain on the nipple and then a washer machine hose on that so i could run it into a bucket without making a mess as i still had to install the shower pan and didn't want to have water all over the floor.


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## easttexasplumb (Oct 13, 2010)

Bayside500 said:


> actually, i just put a rough-in galvanized nipple in the wing ell and then an old boiler drain on the nipple and then a washer machine hose on that so i could run it into a bucket without making a mess as i still had to install the shower pan and didn't want to have water all over the floor.


 
A boiler drain will flow way more water than the hand shower will, you will probably be fine once it is all trimmed out.


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## PLUMBER_BILL (Oct 23, 2009)

*More on loops*





 
Don't know if it's from Kohler, a HACK, or a plumber

but it does address pressure equalizing loops.

I've been through this a couple of times 

Comments greatfully accepted ....


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## Don The Plumber (Feb 14, 2010)

PLUMBER_BILL said:


> How to: KOHLER custom shower system setup - pressure loop & plumbing conections Atlanta tile - YouTube
> 
> Don't know if it's from Kohler, a HACK, or a plumber
> 
> ...


 I love the burnt studs, criss crossed hot & cold pipes, 1/2in copper stub outs for body spray & hand held, (good luck if the tile guy cuts those holes tight to copper ),& the excessive 90's. Just my view.

Personally I would of used a 3/4 brass nip, off top of mixer, & then a 3/4 IPS brass cross, & changed to copper after that.


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## plbgbiz (Aug 27, 2010)

PLUMBER_BILL said:


> ...Comments greatfully accepted ....


I think the tee in the loop for the body sprays should have been centered. As small as the loop is it may not matter.


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## TPWinc (May 30, 2011)

Bayside500 said:


> actually, i just put a rough-in galvanized nipple in the wing ell and then an old boiler drain on the nipple and then a washer machine hose on that so i could run it into a bucket without making a mess as i still had to install the shower pan and didn't want to have water all over the floor.


 Throttle that boiler drian down to 2.5 gallons a minute and see what happens.


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## Protech (Sep 22, 2008)

TPWinc said:


> Throttle that boiler drian down to 2.5 gallons a minute and see what happens.


Exactly. Without the flow restrictors in the shower heads installed the lines are going to flow at twice the normal flow rate or more. More flow=more velocity and higher probability of water hammer or cavitation.


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## mccmech (Jul 6, 2011)

I like where plumber Bills' head is at on this one., no loop means dead-ends.


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## Bayside500 (May 16, 2009)

just to update on this, i tried throttling down the boiler drains that i had on the rough-in nipples and it made no difference at all, so i cut in some 18" long, 3/4" air chambers and it fixed the water hammer problem.

i installed them in the location i marked in light red on this picture.

you can still hear the solenoid valves click on and off, but i am pretty sure once the walls are insulated and durarocked and then tiled, it will be quiet.


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## Gettinit (May 9, 2012)

I would have put it on the feed to the valves. Are you going to be able to access it next year....or before. I would, if you didn't already add a schrader valve.


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## Bayside500 (May 16, 2009)

Gettinit said:


> I would have put it on the feed to the valves. Are you going to be able to access it next year....or before. I would, if you didn't already add a schrader valve.


i originally installed 3/4" hammer arrestors on the 3/4" hot and cold feed lines near the valve boxes before i teed off to each valve box, those were not the pipes that had water hammer on them, but installed them as per instructions from kohler.


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## evan (Dec 10, 2010)

Just wondering, doesn't your DTV have 6 outlets? Why not just use one DTV, one interface, and one port for each head? (4 bodysprays,1 showerhead,1handheld)


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## Bayside500 (May 16, 2009)

evan said:


> Just wondering, doesn't your DTV have 6 outlets? Why not just use one DTV, one interface, and one port for each head? (4 bodysprays,1 showerhead,1handheld)


each DTV has 2 inlets and 2 outlets, it is the smaller version i guess


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## Bayside500 (May 16, 2009)

just to put this thread to rest, i trimmed it all out the other day and no water hammer is heard at all.


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## johnlewismcleod (Apr 6, 2012)

Bayside500 said:


> ...so where would be the best placement of arrests...?


One on each of your girlfriend's...oh, wait! :blink:...I could get banned for that! :whistling2::laughing:


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