| Author |
Message |
Nathan Woods, CCCA, LEED AP
Senior Member
Username: nwoods
Post Number: 140
Registered: 08-2005
| | Posted on Friday, December 01, 2006 - 11:08 am: |    |
An owner/builder client is asking to use PEX piping for potable water inside our high density wood framed housing units, in lieu of our commonly specified copper piping.
I'd done some research online, and am having a hard time drawing a conclusion about this proposed substitute.
Anyone have any qualified opinions on this issue? |
Richard A. Rosen, CSI, CCS, AIA
Advanced Member
Username: rarosen
Post Number: 5
Registered: 08-2006
| | Posted on Friday, December 01, 2006 - 11:30 am: | |
Most the plumbing contractors on our residential projects in the North East have used the system for some time now. Our MEP consultants specify PEX and the DC/VA contractors exclude it when the qualify their bids. The PC's bidding on several of our high multi-family projects in the DC/VA Metro area absolutely refuse to use the system. The NE guys say it is cheaper and faster. The DC/VA guys say it is more expensive. I just don't get it. |
Nathan Woods, CCCA, LEED AP
Senior Member
Username: nwoods
Post Number: 141
Registered: 08-2005
| | Posted on Friday, December 01, 2006 - 11:40 am: | |
Well...in my opinion based on research I did this morning, PEX seems okay, perhaps even beneficial.
The most significant drawback I have found is limited high temperature use. It cannot be used where water heater outlet temperatures exceed 180 degrees F. This should not be a major problem, as the temps are normally set at 140 I think. It depends on the length of the run. In the housing units with individual water heaters, I don’t anticipate this being a problem.
Also, there are different grades of PEX. We might prefer to specify a higher grade, such as PEX-AL that has an internal aluminum sleeve sandwiched between two layers of plastic.
Benefits that are worth considering include the following:
- quieter flow noise than copper (no water hammering)
- longer runs with fewer connections and potential leak points
- less prone to sweat, thus less prone to add to mold/mildew potentials in concealed spaces
- less expensive to install
- faster hot water delivery (pipe doesn’t absorb the heat)
- more resistant to mineral deposit buildup
- more stable pricing (unlike copper which has spiked dramatically)
Links:
- PEX FAQ’s: http://www.ppfahome.org/pex/faqpex.html
- Plastic Pipe Institute tech info: http://www.plasticpipe.org/pex/tech_info.php
- Real world comparison: http://www.builderonline.com/industry-news.asp?sectionID=28&articleID=376862 |
Ronald L. Geren, RA, CSI, CCS, CCCA, MAI
Senior Member
Username: specman
Post Number: 366
Registered: 03-2003
| | Posted on Friday, December 01, 2006 - 10:54 pm: | |
Just to add a bit of controversy to the mix, here's a link to an article posted on the California Pipe Trades Council's website that has a different opinion about the material:
Calpipes.org article |
Nathan Woods, CCCA, LEED AP
Senior Member
Username: nwoods
Post Number: 142
Registered: 08-2005
| | Posted on Monday, December 04, 2006 - 10:57 am: | |
I had found that same article earlier in my research, but discounted it as fearmongering. Too many intangible claims, too little facts. |
Tobin Oruch, CDT
Senior Member
Username: oruch
Post Number: 37
Registered: 04-2003
| | Posted on Monday, December 04, 2006 - 01:15 pm: | |
On high temp issue, the pressure/temp relief valve on most hot water heaters is set to vent at 210 deg F, so if a thermostat fails the hot water lines could see temps almost that high. A conservative design would have to assume tstat failure could happen and use piping that could take it. Watts t/p valve: http://www.watts.com/scripts/pro-products.watts?_cfg=./db/pro-products.cfg&_fil=cat2%3d'Temperature_and_Pressure_Relief_Valves'.and.cat1%3d'Relief_Valves'.and.div%3d'_watersafety-flowcontrol'&_sn=pro-products&_tar=_view5_watersafety-flowcontrol |
John Bunzick, CCS, CCCA
Senior Member
Username: bunzick
Post Number: 614
Registered: 03-2002
| | Posted on Monday, December 04, 2006 - 05:54 pm: | |
I thought that the pressure relief valve would dump the hot water directly into the DWV system of a building, generally a short distance and could be copper. How would it get into the hot water supply lines? |
Tobin Oruch, CDT
Senior Member
Username: oruch
Post Number: 38
Registered: 04-2003
| | Posted on Monday, December 04, 2006 - 06:35 pm: | |
Someone open a tap -- after tstat failure but before RV opens. Would also scald themselves. System could even refill and cycle back and forth a few times before someone caught on. Don't know how likely... |
Tobin Oruch, CDT
Senior Member
Username: oruch
Post Number: 39
Registered: 04-2003
| | Posted on Tuesday, December 05, 2006 - 10:56 am: | |
Looking in UPC2003, PEX-AL-PEX meeting ASTM F 1281 is allowed and even suggests if can tolerate 210 deg F, so temp issue seems moot. |
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