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1victorianfarmhouse 11-26-2011 08:29 PM

Air Chamber Usage?
I'm replacing the old galvanized iron hot water supply lines in my basement, and there is a 6" section of pipe with a cap oriented down vertically. It looks to me like an old air chamber, but everything I read is they should be vertical upward. There are no chambers in the cold water system, but there were several sections that once led somewhere but were later capped off.

I don't have any problems with water hammering or pipe noises, pressure coming from the well is at it's highest around 60 psi.

I took a look at the plumbing in my mother's house built in 1988 to all modern codes, and there are no chambers built into the system that I can find in the basement.

What sayeth the experts here on the usage of air chambers, for lack of a better description?



joecaption 11-26-2011 08:38 PM

Your right an air hammer would have been up, that one's for any solids to fall into instead of going down line.
You see them on gas and air lines all the time.
It's called a drop leg.

1victorianfarmhouse 11-26-2011 08:57 PM

Thanks! Very interesting, as it does have a threaded plug at the base, so it will be interesting to see what's in it when I dismantle it tomorrow. Plenty of rust in these iron old lines, even it they look good on the outside. I've found some 3/4 cold pipes that were so plugged up I couldn't get a #2 pencil through parts.


joecaption 11-26-2011 09:45 PM

What are you replacing it with?

1victorianfarmhouse 11-26-2011 10:30 PM

Copper. I know, I know, PEX is the new best thing, etc. But I'm a bit old fashioned in an old Victorian house and like copper.


joecaption 11-27-2011 05:47 AM

My biggest fear when working in an old house and soldering is fire. Most were done with ballon framing which acts as a chimmney when it starts burning.
Places like behind the bathtub faucets where your going to most likly find a 2 X 4 holding it in place that's been there since the house was built scare me the most because your working so close.
Plus I can run one pipe up inside an inside wall from one floor to another in one piece with Pex.

Redwood 11-29-2011 08:56 AM

Hi Vince,
I suspect that the line dropping down was probably supplying something at one point and was removed from service. Drop Legs would not be used in a water supply system and code does prohibit dead ends over a certain length. Drop legs are used in gas piping.

As for pressure chambers they are useless as the air charge is rapidly absorbed into the water rendering them useless. Yea I know many plumbers still swear they work, but when pharmaceutical companies do drug trials some people have been cured or, have side effects from the placebo as well... :2cents:

Instead if you have a line that needs a hammer arrestor installed on it such as a washing machine line, dishwasher line, or, a tub/shower valve, use a real hammer arrestor where the water is separated from the air charge by a piston.

Sioux Chief has some very decent hammer arrestors...

1victorianfarmhouse 11-30-2011 10:05 PM

Hi Joe,

Yes, I worry about fire, too. But I am working in the basement, with a thick wood floor keeping anything from going upwards. What I do when working near wood is spray it with water from a spray bottle, then, if the piping is close, use a shield of aluminum as well. I learned the hard way how difficult it is to get damp wood to burn, even with a torch, with my burn pile in the backyard.

Previously copper tubing was run up through the walls, and that is what I'm connecting to from the basement.


1victorianfarmhouse 11-30-2011 10:10 PM

Thanks Redwood!

Now that you mention it, there were several dead ends in that corner, the drop down just looked much neater than the rest.

The clarification between pressure chambers and hammer arrestors is appreciated, I was finding a lot of conflicting information when I started looking.


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