trouble with polybutylene

My house had some of the plumbing replaced with polybutylene 30 years ago. A couple of years ago, I found drips at a couple of elbows under the house. I put a pail under on so I could monitor it by ear.
One was below the kitchen sink. It had been less than a drop a second. A few days ago, it was about ten. It was coming from the floor, at several location.
There's a shelf below the sink, 4" above the floor. The space between is inaccessible. I shut off the hot water at the heater. That slowed it. I shut off the water to the house. Before long, the dripping stopped. I turned the house water back on and got about one drip per second.
That meant the cold pipe was leaking, besides the hot. The pipe fit pretty snugly where they came up through the shelf. There was no moisture on the shelf. I pulled the pipes up about an inch and felt the pipes and connections. I didn't feel any moisture.
This was bizarre. There shouldn't have been any connections between the shelf and the floor, but apparently both pipes were leaking in that space. Most alarming, a beam made from a log, possibly a century ago, had become wet.
In a repair like that, there were a lot of places I could go wrong. I turned on the water long enough to fill some containers for drinking, cooking, and washing. I filled a bucket to flush the toilet. I shut the water off and called a plumber.
I took him to the kitchen to examine the fittings. He replaced the pipes with PEX and the plastic valves with what looked like chrome-plated brass. He said they were better than the plastic valves I'd had.
He found no deterioration in the pipes. He said connectors above the shelf must have leaked. He blew into the pipes but couldn't find a leak. He said anyway, replacing the fittings was good because that plastic got brittle. He tried to demonstrate but couldn't break one.
When he left, I discovered that he'd taken the old pipes. I'd wanted to get to the bottom of the mystery. If the FBI wouldn't investigate the leaks, I would have used my neighbor's compressor.
The next day I found a drip from an elbow he'd put in, under the house. The shelf under the sink had been dry 12 hours after he left, but now there was a puddle. Feeling he wet pipe, I find that the source was the compression connection at the top of the valve. I took it apart and found that the chromed brass that the plastic compression was supposed to seat against, was bumpy. So much for the superiority of metal valves. I got it to seal with plumber's grease.
I can't figure it. The original leaks were much faster. Logically, I knew they had to be above the shelf, but I could find no moisture.
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When you turn off the hot water at the heater, you should open a hot water faucet someplace in the house to release the pressure. Alos leave it open or elese it may repressirize if there is even a tiny leak from cold to hot. Mark
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On 4/26/15 7:08 AM, snipped-for-privacy@yahoo.com wrote:

When I shut off the water at the heater, I opened the kitchen tap to relieve pressure and be sure there was no drip from a leaky valve at the heater. I'm not absolutely sure I left it open when I shut off the house water, waited until the dripping stopped, and turned it back on.
Now I wish I'd invited somebody to document everything with a video camera. When the special prosecutor investigating the leak puts me on the stand, the grand jury will dismiss me as an idiot! ;)
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On 4/26/2015 3:45 AM, J Burns wrote:

Someone else can find you a link. My memory says that type of tubing is known for leaking. I'd get some quotes on replacing all that tubing with some more modern tubing. Pex might work better.
- . Christopher A. Young learn more about Jesus . www.lds.org . .
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On 4/26/15 7:49 AM, Stormin Mormon wrote:

I'd love a link to explain how you can have a big leak with no moisture. After the plumber determined that the leaks must have been above the shelf, I said I must have imagined that water was pouring through the floor like a waterfall because we'd both seen that everything on the top side was dry. He said he'd seen how wet everything below was. I said, "Poltergeist!"
Polybutylene was used for district geothermal heating projects in Germany and Austria at 128F and 150 psi in the early 1970s. Other kinds of pipe have had to be replaced in the last 45 years, but the polybutylene still works.
It's still used almost everywhere but the US. In countries with a K, such as the UK, Korea, and Kuwait, it has a big share of the residential market. If Kansas and Kentucky would revise their building codes, I'm sure it would work fine there.
Where polybutylene subjected to high tensile stress, at a kink or a hard compression fitting, chemicals in chlorinated water can cause whitening, which can, in a few years, progress to failure. Soft compressions fittings seem to prevent trouble.
Maybe the fittings below the kitchen sink began to leak because those taps were used so many times each day, and those connections, closest to the taps, were subjected to the biggest pressure changes. In the cabinet under the sink, those valves could have been pushed by storing something agains them, which would have increased tensile stress at the connectors.
How about Tigerbite connectors? Push-on connectors using O-rings. That sounds soft! Easy to disassemble and reassemble, too. How about the wrench-type compression connections used with plastic pipe. Can they be taken apart and put back together?
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On 4/26/15 7:49 AM, Stormin Mormon wrote:

http://michaeldleavitt.com/mdl/bloggers/entry/polybutylene-pipe
This master home inspector says he hasn't seen many polybutylene failures in Utah, but they are common in some areas of the country.
He says one reason plumbers loved it was that only they had crimping tools, so they would have to be called.
They changed from aluminum rings to copper and still had failures. They changed from plastic fittings to copper and still had failures.
The plumbing industry decided polybutylene was no good. In fact, the manifold system worked. It ran polybutylene from a central distribution point, without tees or elbows. It was excluded from the lawsuit because there was no trouble.
I see the manifold system uses threaded compression connections instead of crimping.
It looks like the guy at the hardware store is right. Threaded compression connections work with polybutylene.
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