[Greenbuilding] [BULK] Pex tubing

[Keith Winston]

Copper is probably the most common umbilical pipe. Only major weakness 
is freeze vulnerability.

You can find Pex-Al-Pex at any good plumbing supply house. I see it on 
ebay too! I get mine at RE Michels, a local HVAC distributor (wholesale 
only).

Keith


Lawrence Lile wrote:
> Might copper tubing be a good choice for the solar loop, especially if
> it is glycol? Do you have a source for the Pex-Al-Pex?  
>
> --Lawrence   
>
>
>
>
> -----Original Message-----
> From: greenbuilding-bounces at listserv.repp.org
> [mailto:greenbuilding-bounces at listserv.repp.org] On Behalf Of Keith
> Winston
> Sent: Wednesday, July 19, 2006 9:09 AM
> To: Greenbuilder list
> Subject: [BULK] [Greenbuilding] Pex tubing
> Importance: Low
>
> Regular Pex tubing is somewhat standardized these days. You can use
> fittings and tools between many (though not all) brands. It's
> temperature rating is well below what solar wants: the top working
> temperature of most Pex is around 180F I believe, and to have some
> margin for error I'd like my solar umbilical tubing to be capable of
> handling something more like 250F. I am currently preparing to
> experiment with Pex-Al-Pex, which has considerably higher operating and
> burst temperatures and pressures. It consists of alternating layers of
> Pex (cross-linked polyethylene) with an aluminum core. It's stiffer, and
> holds a shape, and doesn't kink as easily as some Pex'es do. But all the
> Pex-Al-Pex manufacturers still have proprietary fittings, tools.
>
> There are several different ways to cross-link polyethylene, which
> result in different strengths, etc. Also, in heating systems some people
> argue the necessity of an oxygen barrier, which can also be done several
> different ways. At least one reputable company, Radiantec, suggests it's
> unnecessary. Pex-Al-Pex doesn't require an additional oxygen barrier,
> the Al works as one.
>
> Finally, I spec'ed out a house in Pex fairly recently, for the potable
> water, and subsequently decided I probably won't again. Upon catching up
> on the literature, I was reminded that over and over we discover strange
> chemicals that outgas and leach out of plastics, which very subtly mess
> with our systems. Polycarbonate is used for laboratory animal cages, and
> only when a researcher discovered a slew of results that they couldn't
> explain, did they eventually discover that the cages were releasing
> hormone-like chemicals. I think it was traced to improper cleaning
> chemicals. I will likely continue to use Pex for heating systems. Also,
> an experienced plumber running pex for the first time may not move much
> faster than they could in copper (learned the hard way). Of course,
> copper is getting very expensive, and copper mining is a scourge, at
> least sometimes. Complicated world...
>
> Warmly, Keith
>
>
>
>
>   
>> We used the PEX system in a recently built house.  I believe every 
>> positive thing Lawrence has to say about it is true (chlorinated water
>>     
>
>   
>> is not a problem).  But be aware there are several 'systems'
>> out there and the tools required to compress the rings (to hold the 
>> fittings together) are proprietary to the specific system.  PEX tubing
>>     
>
>   
>> comes in several sizes btw.  I gather it can not be used for solar hot
>>     
>
>   
>> water because it won't expand properly.  Let me know please if I'm 
>> wrong about this latter point.  Sacie Lambertson
>>
>>
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>
> --
> Keith Winston
> Earth Sun Energy Systems
> 3927 Madison St.
> Hyattsville, MD 20781
> 301-980-6325
> keith at earthsunenergy.com
> www.EarthSunEnergy.com
>
>
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-- 
Keith Winston
Earth Sun Energy Systems
3927 Madison St.
Hyattsville, MD 20781
301-980-6325
keith at earthsunenergy.com
www.EarthSunEnergy.com