I'd like to have a discussion to get your feelings on a variety of plastics offered out there currently for water lines & hydronics to get your input. Here is a bit of a summary the way I see it off of the top of my head.
The tried tested & true Bow-pex with those black coloured copper crimp rings - tried tested and true - it carries a 25 year warranty on both the water line stuff and their oxy pex (apparently). My company doesn't use much of this although it is a viable option that I'm sure many of you guys must use.
Wirsbo Pex- great stuff but quite expensive apparently (I don't see the bills much as I just buy the stuff and install it and my office deals with the bills). My boss stopped using this in favour of the Rehau Everloc system some years back though. The one thing I like about Wirsbo is it's great for tight spots in most cases. You pull the pipe out of the wall, pump it up, then push it back into the wall and on the fitting as an example. Downsides are if you dont know the little tips & tricks in dealing with the rings you will have leaks but the upsides are that you won't have any missed crimp rings blowing off (not that a pro would have them but the odd time, etc.). The Oxybarrier stuff in Wirsbo is quite expensive - the Wirsbo heating manifolds are twice the price of the Rehau heating manifolds. The Wirsbo He-pex has an oxybarrier that doesn't squeak which makes it good for staple up under the floor applications in comparison to the rehau radiant oxybarrier pipe. But the Rehau heating Hepex is not suitable for use for potable water which means any tails you have can't be used for water lines if you wanted to save $$$. Carries a 25 year warranty if I'm not mistaken.
Rehau Everloc - As far as security/quality of joints/fittings, the Rehau everloc system is the best system available for Pex in my opinion. The Everloc system is also, at least in my area, the only system that is approved for joints in concrete; if a radiant pipe is damaged during a concrete pour (or before), the everloc system couplings are the only approved coupling/joining system available in my area that is approved to be encased in concrete. Everything else has to be dropped below the floor and repaired and then brought back up. The manifolds are cheaper than Wirsbo, I even believe the pipe might be slightly cheaper, but the Everloc system is definately more expensive. The Everloc system and the tool that you use for it is also a bit cumbersome/PITA to use and not as friendly for tight applications as Wirsbo or pex. The Oxybarrier pipe is suitable for use with potable water compared to the Wirsbo stuff which is not, BUT it has a squeaky Oxygen barrier membrane so it's not the first choice for staple up applications but works great for being encased in concrete. This system carries a 25 year warranty if I'm not mistaken as well. I also believe rehau unlike wirsbo will offer a warranty (If I'm not mistaken) if you choose to use crimp rings with their pipe but it is reduced in time. Also just by eye the Rehau everloc system fittings seem to have a slightly bigger cross section than Wirsbo, Pex, or Kitec systems which should help flow slightly. The other thing is if you buy a 3/4" Copper Female x 3/4" Everloc adapter, the Copper side will also act as a 1" Copper Male if you need it to and this is how most of their Copper to Everloc adapters work (and they also do both - a 3/4" Copper male to 3/4" Everloc adapter will work as a 1/2" Copper Female). Also the 1/2" MIP adapters (to everloc) also act as a 1/2" Copper female if need be.
Both Rehau Raupex pipe and Wirsbo pipe can both be repaired with a heat gun if kinked as they are manufacturered in a very similar fashion I'm told. They also offer identification systems, for instance the Wirsbo rings have different colours (red/blue or white) and the Rehau everloc system pipe (raupex) comes in different colours if you want and also offers a UV barrier on their red/blue pipe.
The biggest problem with Pex in general is it seems to take the tradesman out of the trade. It's much easier to install, but I don't see many who install it properly with bend supports and properly clipping it, securing it, running it, etc. The other problem with pex in general is the the bigger sizes, say 1" plus tend to require special hydraulic joining tools which are expensive (wirsbo/raupex-everloc) and the pipe itself (1 1/4" plus sizes) is also quite expensive.
CPVC/PVC - good stuff but you have the issue of breathing in VOC's with this stuff & the glue/primer can be messy. Also requires a bit more installation expertise compared to Pex systems - similar to copper, and you need to support it more often than your favourite metal counterparts. Also, in heating applications if you wish to transition from metal to plastic you HAVE to use their FIP with metal ring adapters and they can be finicky - Ipex which is the manufacturer we use, does not currently have a MIP adapter that you can screw into brass/steel that will handle temperature fluctuations without leaking ( I believe there is one out there from another manufacturer that is reinforced with brass so it can handle temp fluctuations) - believe me I'm speaking from experience. I also don't know the deal on warranty. I also believe that CPVC can be brittle at times. Never really used this stuff for water pipe other than a bit of PVC sch 80 for water mains. I do like the built in R-value of PVC Sch 80 however. The expansion on this stuff is insane and I'm speaking from experience there too.
Kitec - you know I'm still trying to figure out the benefits of this stuff. It's insanely expensive - I've heard even more expensive than Copper. It is joined by crimp rings like Bow-pex or similar, and it has a thin layer of aluminum sandwiched between an outer and inner layer of Pex or PERT depending on if you are using the heating stuff or the water pipe. It behaves very similarly to that of Soft Copper. Running it for water lines if you kink it the section must be cut out and replaced. Because it maintains it's shape it doesn't look very good and is hard to straighten out (much like soft copper). If you don't have the reeming tool then pushing the fittings in is a nightmare. I'm not exactly sure what warranty is offered with it. It's much more difficult to run for radiant lines compared to traditional pex and there again lies the issue of if you kink it you're basically screwed if you're pouring concrete overtop of it and you want to legally repair it (the kitec crimp ring fittings aren't approved for encasement in concrete where I live). It may have better heat transmission properties because of the aluminum, but, then I heard there may currently be a few lawyers trying to set up class action lawsuits because of the apparent touching of aluminum to their brass fittings at the end of a joint which may cause corrossion issues. You also need seperate crimpers to use this stuff (too bad they couldn't have designed it to use with pex size crimpers). Perhaps the aluminum layer helps with fire rating but I still don't see the benefits of this pipe in all honesty. You can get it in orange (heating), red or blue (water lines).
We got a heating call from someone recently where they had a 5/8's kitec line in their heating system that needed to be repaired. They wanted to find a contractor who had a set of the 5/8's crimpers, which we used to have which have gone missing (and we're not missing them - we don't really use the stuff much if at all), and they didn't want to have to foot the bill for a contractor to have to pay for them. What a PITA.
And then there is Fusiotherm. A buddy of mine who is a master plumber in my company and someone who I apprenticed under for a bit has really championed this stuff. He really sees it as the wave of the future as far as what we will use in a lot of future jobs. The fitting system is awesome with saddle fittings, street fittings, MIP/FIP adapters, valves, etc. I really am going to try and do one of my next mechanical rooms in this stuff once I get the hang of it (current job is rehau/copper so it'll be about half a year until I can really start using it). The Pipe itself is permanently fused with the fusion iron (one piece after the fusion is done) and it comes in small to large sizes. It's also in metric and the 1/2" equivilent has an excellent cross section with higher flow rates than comparable plastics or even copper. Here is their website for a bit more info: http://www.fusiotherm.com/306.0.html
They also offer these heating grids for radiant heating & cooling which you would preferable install in the wall or ceiling, and they offer seperate heating & waterlines pipe. The only issue with this stuff is it is definately not the most installer friendly as far as tight spots and requires a bit more planning due to the use of irons to fuse it. It definately puts the trade back in tradesman however and I really look forward to using it/trying it anyways, so I'll try and do a report when I get more experience with it. Current reports on the big job we are using it on though are quite favourable from the guys I've talked to in my company who use it.