Large PEX

Karl_Northwind

What are everyone's opinions on large diameter pex? 

I have an upcoming project that will be using 1.5 and 2" distribution piping, at low pressure and up to 180F. 

We have used lots of ProPex over the years, and love it, and use the battery expander.

I'm looking for opinions on the larger diameter stuff, and should I use Pex Al Pex, or regular PexA? 

if PAP, What fastening system should I look at? 



Thanks

Karl

EricAune

Heavy lifter

Keeping within the operating limits of the PEX you select is a no brainer, as I'm sure you are well aware of.



I have installed [what seems to be] miles of larger diameter PEX for projects like car washes and warehouse buildings.  All a mixture of both radiant and plumbing piping.  All of the large stuff I have installed has been below grade/burried.



There are two things I can tell you from experience.  One being be prepared to struggle while trying to handle anything over 1" respectively.  Once you get up to the 1 1/2" sizes I don't think it matters much what type of PEX it is [unless it straight sticks] it will be very stiff and require some horsepower to get it to where you want it to go.



Second being if you have hydraulic or electric powered tools for joining you will be much better off at the end of the day.



Good luck!

Mark Eatherton

And don't forget about expansion...

and contraction.



As Eric said, be prepared to use small automobiles as anchors to hold this stuff in place while you are back filling. It WILL want to curl back up on you otherwise, If you hear a whooshing sound as you are rolling it out in your trench, be prepared to DUCK and COVER, cause it's probably headed at you at the speed of light from behind...



It has been a while since I've worked with it, but in the Wirsbo/Uponor world, when getting into the larger sizes, it comes from Europe, and has to use special compression fittings to make the adaption from PEX to IPS.



Wear eye/head/chest/body protection.



ME

Karl_Northwind

distribution

this will be in the building, not buried.  There is some buried already, but that's not the issue, the issue is the stuff I'll be using to distribute to a pair of fan convectors in the building.  I need 13 gpm  per convector, was planning on using 2" and 1.5" to do the deed.  I really would like to avoid the cost of copper and the headaches of iron. 

it's about 20 feet up,  and 20 feet to the near one, and another 50 feet to the far one. It's in a greenhouse, so the ability to curve to the building shape would be really cool.

Karl

hot_rod

what about press fitting and steel

I see at least one company has press fittings for steel pipe, supposed to work on schedule 40? www.cimberiovalve.com Fast Lock fittings. Looks like the jaws fit REMS, Ridgid, Rothenberger, Stanley, and Virax tools.



Victraulic has a press fitting system for sch 5 stainless. Stainless may be less then copper?



Viega also has a thin walled stainless press system.



I used Wheatland Tube MegaThread on my collector repipe. www.wheatland.com



It's a tube the fire sprinkler industry uses. It is a bit thinner wall than schedule 40, less weight and less $$. A nicer, smoother outer coating compared to black steel sch 40 pipe..



Next time I'd try that tube with a Cimberio press fitting.



hr

meplumber

Consider UV exposure in the greenhouse.

I am sure you have covered it, but all forms of pex are prone to failure due to exposure to UV from sunlight.



Just something to consider.

CMadatMe

Have Done

A few jobs with Uponor large diameter. Fittings are not cheap and must be purchased in "Bag" quantities unless you find a wholesaler who has them readily available on the shelf. We get our contractors the hydraulic expander tool as a rental which will keep you from having to hit the gym to "buff up" for the job.



Tubing is way, way less expensive then copper.

Charlie from wmass

Wow I sound like my father right now.

Why not just run iron? If it is exposed to the lights and the rigors of a green house I would go iron. Especially since it is not that far you are running. It will look better for years to come if you use iron. It could be victaulic fittings if you think the green houses will be moved any time soon.

Karl_Northwind

pretty slick

some pretty slick options there, the learning curve probably won't be there for this smallish project, but for larger ones, the cost savings may be well worth it. 



something new to learn!!



Probably going to stick with copper for this one, for a number of reasons.



K

NRT_Rob

is it possible

to upsize the convectors to run with cooler water?



if so, you could do a "minitube" design. send 180 out with a VS Injection control .... or design for a 60degree dT = very small flow rates.



downsizing to 3/4" or even 1" would probably pay for the pump and controller a couple of times over, to say nothing of the labor. final pumping power usage would probably be lower too.



sometimes you need what you need, but many times you can "cheat".

zacmobile

aquatherm

I did a greenhouse using 50mm (1-1/2") and it was real nice, no heavy lifting or uncoiling required! It is another tool investment though, but I think they are a lot cheaper than the big expander tools.



http://www.aquathermpipe.com/

Karl_Northwind

cool

that looks like cool stuff as well.  Large process piping would be pretty slick with that stuff.

K

Mark Eatherton

Caution.....

According to the manufacturer, regular Climatherm does NOT have an O2 barrier.



Climatherm OT DOES have an oxygen barrier.



I remember when Goodyear was making the claim that Entran II had an oxygen barrier. In fact, in reviewing thier literature, we found it had three totally different positions in the tube wall construction, but further testing found there was NONE at all...



Not saying these people are the same, but they seem to blow off the need for O2 barrier, because "as oxygen permeation is very low and not found to cause any problems. In most applications, it will not affect the pipe if oxygen removal or treatment is added to protect the mechanical equipment. Submitting a chemical inquiry form can verify the suitability of the treatment. The new Climatherm OT is made with an oxygen barrier for applications where simple treatment is not sufficient."



If it is REALLY so insignificant, why offer a pipe with it (O2 barrier) at all?



Proceed with knowledge and caution.



As for mini tube and PEX, I am not a big fan of that technology. I know SIggy is a big promoter, but I am not a fan because I have seen the O2 barrier delaminate from PEX due t long term exposure to high operating temperatures, and even if the barrier didn't snake skin, the diffusion of O2 through the walls of the pipe increases as the pipe surfaces goes up.



That, and the fact that your heat source will be out of condensing mode the majority of the time, but if you are using woody biomass boilers, I guess the lack of condensation is in your favor...



At that point, you can afford to do it in copper (keep maximum velocity in check) and it should work just fine. If you opt to use PEX, beware of its high coefficients of expansion, and its hate for UV exposure.



ME

NRT_Rob

if you can get down to a reasonable size

then PAP pipe might be best if the temps are high. I've never seen that delamination but I don't do a lot of super high temp systems... though the OP was talking about using high temps already, I'm just advocating for much wider delta-T to drop flow requirements. all he has to do for that is upsize the terminal units.



I love low flow design.

Karl_Northwind

temps

The high temps in this case just to be able to get more heat storage, and take advantage of the higher temps the garn will reach pretty easily.

I have sized the fan convectors to hit peak heat load down to about 160F incoming water temp and a 30deg delta T to allow lower than max flow, both to reduce pumping power and reduce piping costs.  the water would be mixed down to about that 160 F, and then drop below that when the storage temp lowers.  the LP fan convectors will pick up the slack till the hydronic convectors shut off at about 120 supply temp.



due to the UV issues, temp concerns and the fact that I can downsize one for copper (1.25" rather than 1.5 Pex)  and that I really want this system to look really nice (no droopy pex) I am going to go with copper. 

I'm really interested in alternatives to copper and even alternatives to pex, and I would like to see this thread live on as alternatives to copper become more attractive. 



cheers,

karl