Air Chambers Necessary?

Herk

My opinion of air chambers is that they simply don't work. Mechanical air chambers are preferable to plain copper ones. The plain ones reportedly saturate after a few weeks and become useless.

In my area, we use PEX. I still use copper for building a tub or shower valve assembly, but otherwise avoid it. PEX pipe requires no air chambers since it's quieter and self-cushioning.

But back in the days when we were using copper for new housing, I did not use air chambers and there were no problems with water hammer. Back in the day, when seat and washer faucets were common, there were many problems. When you get water traveling 80 feet per second and stop it suddenly it can bang. When the threads in the faucet wear out, or a toilet fill valve has parts that can vibrate, you can get that hum that sound like a 747 coming in for a landing.

But newer faucet designs have all but eliminated such things.

My vote: no air chambers.

BigMikeB

I always use mechanical arrestors on equipment with solenoids on the inlet water line. Some people have a hard time describing a noise they hear and from process of elimination I find often it is water hammer or just movement in lines hung poorly on reznor hooks. I was at a medical office a few weeks back where the 1/2" copper lines had rub marks like two inches long from rubbing against the hooks, when I cut them out the copper was paper thin. They never complained about noises there. Air chambers or arrestors on the washing machines and hydrotherapy tubs would have saved them that repair.

Ron The Plumber

He's right your nuts, you don't need them, only place they will work and thats in a commercial applications, like a commercial dishwasher, waste of money in a residential application.

rex

in michigan they are required on the gray box and the diswasher....i will use 3/4 air chambers on custom shower set up with a thermostatic valve but thats it...and i wipe my copper joints with my finger then clean it up with a rag

bauler

Stupid question, but why do you have to wipe your joints besides looks.

Ron The Plumber

Because if you don't wipe the joints it means you don't put in air chambers, which makes a plumber non-caring about his work. So wipe your joints so we know you use air chambers.

Grumpyplumber

Here, we're required to put 3/4" chambers on all shower valves and laundries.
I'd call it redundant, but experience has proven otherwize.
Ever hear a "thump" when the shower is turned off?
When the washing machine shuts off?
Often on older homes I install expansion tanks or PRV's with them to alleviate piping with no chambers.
I like that "Killer"'s code requires them on everything.
Also, wiping the flux off joints doesn't make a difference now...
Go back in a year and flake off the green copper and see how much material was eaten away.

MechanicalDVR

Looks like not every plumber you ask will tell you no air chambers. Looks pretty divided to me.

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Teetorbilt

Watch your pipe sizes.

I'm not a plumber but am a Fluid Engineer and former Civil Engineer with the utilities dept. for a large city. The most common water meter is 3/4", you will not get any more than it can provide. You have to consider your end use. 6 showerheads + a rain head + toilet + 2 sinks may lead you to think that 3/4" might be needed but what are the odds of having them all running at once?

I posted this years ago but it bears repeating. I was working for the aforementioned utilities dept. when one of my cohorts decided to replumb his 1920's home. In his haste, he forgot the end point use rule and plumbed the entire house with 1 and 3/4". It took over 3 mins. to get hot water to the master shower

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Grumpyplumber

I always use the smallest diameter on hot lines I can...for that reason and also the fact that when you turn off the water you have a larger volume of standing hot water that goes to waste and cools off.

As far as a home with as many as 6 shower heads...I'd assume they're either full or half baths...something that size would require a 1-1/4" to 1-1/2" water main. Even though the meter ports might be 3/4".

KillerToiletSpider

Meter size in Chicago is based on the water service size, one pipe size smaller than the incoming service, so a two inch service would get an 1-1/2 meter.

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Ron The Plumber

To size the water lines properly it thats there known facts.

Elevation from meter to highest fixture being served.
Number of fixture units being served.
Designed working pressure.

With out these known facts you can't properly size the water lines. When these are known then your code book will dictate the size required.

Grumpyplumber

This is where it gets interesting.
We're not UPC here, so I'd be curious to see the differences state by state.
In my code:
3/8" feeds on a fixture are a factor of 1
1/2" is 2
3/4" is 6
1" is 12

Most residences have nothing morre than 1/2" feeding individual fixtures...except for higher end/high volume 3/4" showers, roman tubs etc..
("Killer" will chime in I'm sure...this is his specialty)

Sizing a water pipe relative to height to fixture has no bearing on pressure.
Here we add booster pumps when needed based on incoming pressure vs .434 psi per foot in height. (usually if the pressure gets below 40 psi...but the target pressure is 60.)

We have a "demand factor" sizing chart that dictates how we size the main....a common residential demand factor is .5 (you divide the added factor value of all fixtures by this...commercial/industrial have different demand factors...etc.)

A "standard" bathroom group's factor adds up to 7...with hot and cold.
Lav has two 3/8" feeds...toilet one 3/8", shower has two 1/2".

Minimum water main on any residence incoming is 3/4"...for the obvious reason....

The sizing chart we use calls for 1/2" up to a 4.0 total factor (after demand factor has been figured)
Broken down:
1/2" up to 4 factor values
3/4" up to 9
1" up to 16.6
1-1/4" up to 28
1-1/2" up to 55

Water meters are installed by the local DPW and usually go in as 3/4"...obviously not on larger mains, but they make the call (which seems rediculous when you install a 1" and they show up with a 3/4")

Ron The Plumber

Min service size is 3/4"

Max number fixture units in 1/2" is 7.

Resident Fixture units under UPC Oregon Admendments

Bathtub 4
Washer Machine 4
Dishwasher 1.5
Hose Bibb 2.5
Additional Hose Bibb 1
Laundry Sink 2
Lav 1
Shower 2
Toilet 1.6 gal Gravity Tank 2.5
Jetted Tub 4

Most meters are 3/4" size.

Grumpyplumber

Geesh...I speak latin, you speak Greek.
Did you mean Factor values?(For water) or Fixture units? (for drainage)
I'm going after my UPC license in a bordering state and it's lookin' uglier all the time.

Ron The Plumber

Here fixture units mean are either or.

Grumpyplumber

I could only wish.
Certainly makes it easier for sizing water AND drainage.
We use two completely independant sets of charts / formulae for each.

Ron The Plumber

There is two different charts we use but drainage units are not the same as water distro.

WSFU Water Supply Fixture Units
DFU Drainage Fixture Units

Grumpyplumber

Again..Latin/Greek.

Another notable difference...we use a simple formula for vent distance from trap weir...d X 2+2= distance in feet...in other words
2" X 2 + 2 = 6' from trap on 2" drains, 1-1/2" is 5', 3" is 8'.
I'm told UPC has a chart you refer to, usually comes out a little further.

Ron The Plumber

Distance to vent under upc is.

1-1/2" = 3.6"
2" = 5'
3" and 4" is 6'

For closet distance that's total developed length from top of flange, distance includes the vertical and horizontal length before vent.

So to answer your question, no yours are further