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Schedule 80 vs 40 CPVC

5K views 19 replies 8 participants last post by  a_lost_shadow 
#1 ·
Is the 80 overkill? for replumb?
 
#19 ·
Just did a repipe today on a house, I couldn't roll over underneath the damn place, and I am 6'0" a buck eighty ; not a big guy. If I had to do that with copper, it probably would have taken at least 2 days..... having to pull all the insulation down just to be able to solder joints, and then put it back up after.... no thanks. Copper is great, but pex has it's place too. <3 pex bandwagon today.
 
#20 ·
digitalplumber,
I did a replumb of my house about a year ago with PEX and did have some experience with strong plasticy taste, and in some cases odor. The taste and odor were definitely related to how long the water stayed in the pipes. On the filp side they went away over time, or if usage went up. I stopped noticing the odor after a few months. The taste took around 9 months to go away. Though I did notice a few hints after coming back from vacation. After that initial time frame, if you don't notice the difference between drinking from metal and plastic water bottles, you won't notice the difference from the pipes.

As I mentioned, usage also makes the taste/odor go away. About a month after the replumb my parents came to visit. So my 1 bathroom house went from supporting just myself, to the three of us. For the duration of the visit, I only noticed the barest hints of taste/odor if I was the first to use something in the morning. As soon as they were gone the taste & odor came back just a bit below where they were before their visit.
 
#2 ·
Schedule 80 is much more expensive than 40 and you will never win a bid quoting sch 80. You will probably lose to another plumber quoting PEX.
 
#4 ·
Then just overkill. The only advantage to schedule 80 is the increased max pressure rating (which you will never see in residential applications). You will also reduce the flow rate unless you increase the size.
 
#11 ·
Never heard about water taste..
And yes, you can have flow reduction as you can with any pipe you use. Just have to know how to size the line properly.
The joining system and type of fittings also play a factor in flow characteristics.
I like to use the ProPex expander system but the tool is spendy for one project. ProPex/Uponor uses full size fittings.
The crimp system uses smaller ID fittings that will affect the flow if not considered in the line sizing but still is quite popular. You can rent crimpers too.
 
#12 ·
+1 with what he ^^^ said.

I re-plumbed my house 5 years ago with PEX (crimp rings). I used 3/4" trunk lines to mini-manifolds and 1/2" to each fixture. I installed a shutoff to each fixture after the mini-manifold. No issues with flow or pressure.

No taste issues and why would there be any difference than CPVC.

I am surprised that you as a plumber are not already using PEX in some applications.
 
#14 ·
PVC pipe rating is 289 psi for 3/4 inch pipe schedule 40, 509 psi for schedule 80. CPVC rating is 480 psi for Schedule 40, 690 psi for schedule 80. 1/2 inch pipe is considerably higher. CPVC and PVC both derate with temperature. At the maximum operating temperature for CPVC of 200 degrees F, the allowable pressure derates to 20 percent of the rated pressure quoted, which is for 73 degrees F.

You are not going to run your domestic hot water at 200 degrees, typically hot water is at about 120 degrees F, at which temperature CPVC derates to 70 percent, and PVC derates to 40 percent. Even at 40 percent capacity for PVC, in theory you would have an allowable pressure of approximately 120 psi for 3/4 inch PVC at 120 degrees F, however PVC is not recommended for hot water applications. In any case, there is no reason to use schedule 80 CPVC, it is overkill and more expensive, but if you already have it, you can certainly use it.

By the way, I concur with the recommendation to use PEX, but I realize this is controversial on this forum and elsewhere.
 
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