Image Credit: Image #1: Zurn Industries
More Q&A Spotlight
Building his “forever house,” Dean Sandbo is mulling what type of tubing to use for his plumbing supply lines. He has narrowed the choice to one of two types of cross-linked polyethylene (PEX): PEX-A or PEX-B.
Key issues, Sandbo notesin his Q&A post at GBA油管会持续多久,是否there are safety concerns — that is, will the PEX tubing leach chemicals into his drinking water?
“I am on a well,” he writes. “Any input as to the longevity and safety of these two different types of pipes?”
Although that’s where the discussion starts, GBA readers quickly turn to another potential issue: What’s the best way of achieving a leak-free connection between tubing and fittings?
That’s the topic for this Q&A Spotlight.
Characteristics vary by type
There are actually three types of PEX, as a reference article supplied by GBA senior editor Martin Holladay explains (see the “Related articles” sidebar below). Types A, B, and C are manufactured differently, which affects characteristics such as flexibility, resistance to chlorine and oxidation, coil memory, and cost. The lettered designations aren’t grades, just references to the manufacturing process.
For Richard McGrath, PEX-A is at the top of the heap. “PEX-A is produced with a better manufacturing process than PEX-B as the crosslinking takes place during the extrusion process,” McGrath writes. “PEX-A products usually achieve an 85% crosslinking while PEX-B products average a 65-70%.”
PEX-A is more resistant to the chemicals commonly found in plumbing and heating systems than what it has replaced, he adds, and long-term testing by Uponor, one of the manufacturers of PEX-A, is very encouraging. The company holds an unofficial record for resisting high temperature and pressure, McGrath says, holding up to 175 pounds per…
12 Comments
polypropylene
Polypropylene is great as far as taste and is also one of the better plastics as far as environmental impact of manufacturing. The downside is that, as far as I know, there's no way to do any work on it without a special heat welding system. Few plumbers in the US have those systems. I hope that will change, but for now I'd be hesitant to install that system unless there are at least two plumbers in your area who have good reputations and have the tools to work on it.
Thanks for pointing out the Legend Hyperpure alternative. It would be interesting to see some third-party reporting about it.
那呢？
I had a plumber work on my system recently, and he used Sharkbite push-to-connect fittings to change around some of the pex lines. Any concerns about the reliability of these pieces?
页
The heat welding systems for PP aren't terribly expensive for residential pipe sizes (<2"), around $1k if I recall correctly. You can easily drop $2-3K on battery powered expanders / crimpers for Pex.
The real downside (other than cost) is that it requires some additional planning for fittings and connections, and can't be used in a small diameter home-run system like pex can. So if you don't like waiting for hot water, you're back to a circulation loop.
I REALLY don't trust sharkbite fittings. They're expensive, and the seal there relies entirely on a rubber washer that is likely to wear out much quicker than the PEX, and if we're already worried about the PEX longevity...Particularly w/ chlorinated water, I don't let them in the houses I work on.
OnOn ot ot ot配件不是
OnOn ot ot ot配件不是"unrestricted" or "full flow". Not even very close, either. A quick look at the specs will confirm this. They're just *less* restricted than typical PEX fittings.
Inner diameters for 1/2 nominal products:
Uponor PEX tubing: 0.475"
安装：0.378“
Standard PEX fitting: 0.350"
Sources:http://www.uponorpro.com/~/media/Extranet/Files/plumbing%20literature/AquaPEXProPEX_Compare_C274_0211.aspx?sc_lang=en
http://s3.supplyhouse.com/manuals/1295550221872/44591_PROD_FILE.pdf
You can also see it clearly if you have physical access -- the fittings are clearly smaller on the inside than the tubing.
Reply to Steve
The main downside of Sharkbite fittings is their price. Most of the builders I know are comfortable using them in locations where they are exposed but are still reticent to bury them in walls. There is no reason to doubt their integrity, but a lot of us would rather wait and see what their long term reliability is. Most other fittings that rely on rubber gaskets for their seal are fixtures, like faucets or hose bibs, where the consequences aren't as large if they do fail.
混合管道?
如果化学物质通常是从PEX中浸出的，为什么不将polypro用于饮用水的常见来源，然后将PEX用于其余部分，尤其是家庭经营的热水呢？
Dustin's idea
Dustin, I think that's a great idea.
Mixed plubing
We've looked at that on a couple houses, but in both cases the owner's opted for either full PP or full PEX. The reason is that one of the speculative downsides of PEX is a shorter service life...so if you're paying to do a good chunk of the system in PP (including the line from the street), you might as well go whole hog and get "forever pipe" everywhere.
I could see doing it in a very large house, though.
混合管道
Chemicals added to a plumbing system (as when you drip chlorinate) are considered to be fully dispersed after 4 diameters of pipe length. Is there any research that suggests that chemicals leaching from pex pipes would stay isolated within what is a common, open water supply?
我们知道，进入房屋的加压供水可能会影响其附着的市政系统。如果有PEX浸出的化学物质，它们可能会同样最终出现在所有房屋的水中。
Thanks, Malcolm.
I won't worry about changing out the Sharkbites then. But after reading this thread, I think I will reinstall my wholehouse water filter.
Uponor fittings
The question remains, which isn't necessarily answered in this article, does one risk using a fitting system other than Uponor, if by doing so you would likely have no warranty coverage. What Richard McGrath lays out seems pretty straight forward. Plumbers use other fittings, WHICH WILL WORK, however, if plumber/consumer want the manufacturer to honor a warranty to claim, they better have used the Uponor fittings.
Seems like a no brainer to use them. Am I wrong?
对MS的响应
MS,
If I understand Richard McGrath correctly, he is a big fan of Uponor tubing. That's fine -- lots of people have favorite brands. If you are using Uponor tubing, you need to use Uponor fittings. That's as expected.
If you choose a different brand of tubing -- say, Nibco tubing -- then you use Nibco fittings. Again, no surprise.
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