CPVC might be better than PVC, but it's still way worse than copper or pex. Both PVC and CPVC will shatter if stressed beyond it's yield strength. Go hit it with a hammer, and compare that to hitting a copper pipe or pex. This is also the reason why pvc is super dangerous for compressed air.
It's certainly not 'way worse'. CPVC/PVC has its advantages and disadvantages, just like every other piping method. CPVC can become less pliable over time, particularly for hot water, but properly (by code) supported/strapped and glued, it can last for decades. It, like PEX, should be run to a well-secured, copper stub out where it sticks out of the wall in an area where it could be damaged.
Copper is not without its disadvantages: it's outrageous expensive as of late, soldering can be dangerous (banned in some cases due to fire risk), it takes longer to install than most other options, and some water supplies have a composition that leads to premature failures.
PEX is a universe of options: PEX-A, PEX-B, crimp rings, clamps, plastic/brass fittings, etc. It also needs to be properly installed - PEX B has very specific locations for the crimp/clamp rings on the fitting, and the difference between a proper crimp/clamp and a failure waiting to happen is very subtle.
We build most houses to last for centuries when properly maintained. We also know from experience that few houses go more than 50 years without a major remodel so we don't overbuild making that impossible.
People's needs change. Technology marches on. My house was built in 1973, next week i'm throwing away a furnace that is still working like new because it is 60% efficient. I don't know how efficient the air conditioner is, but it is being replaced by a heat pump that will be better. If it wasn't so expensive the windows that are working like new would go as well for something more energy efficient. I'm also considering (unlikely but considering) options to make my kitchen larger like what a new house would have as this lacks some functionality of a modern kitchen. Previous owners added a few extra bedrooms in the 1980s. This house was built without cable tv or internet wiring, some of that was added latter, but not to every room (and.with modern wifi probably isn't needed anymore. I haven't tested, but i'm sure the pipes were soldered with lead, the paint might have lead underneath, and there could be asbestos in places.
My house is typical for a house its age. I have no idea what people will want from a house in 2073, but it will be at least somewhat different from today. Some of that will be style of course, but some will be real functional differences.
It's not like these needs can't be anticipated. The wiring problem can be solved by running conduit, or at least making fishing easy. As for the heating, the basic problem of pushing around hot air or hot water just isn't going to change, regardless of the details of how it's accomplished.
My point is that it's possible to build a house with with a lasting structure that can be updated for new technologies as they arise relatively easily, but we don't do that because the home building industry is overrun with corner cutting.
If you visit old houses (pre-war) you can see that the general quality of the construction is just considerably higher than the crackerjack boxes we've been erecting since the '50s. Sure, there is an element of survivorship bias, and some of the legacy stuff is ugly to deal with (lead paint, asbestos, horsehair, and knob and tube, I'm looking at you), but overall they were built to last in a way that new construction today just isn't.
You obviously have not looked at old houses in detail. They are far worse quality than today. Sure they may have used old growth lumber which was slightly stronger, but they had no concept of what was quality. I've seen 2x4 used for floor joists, no insulation in walls, and many other engineering failures. And of course there is survivorship bias, the worst examples are torn down already.
Sure the old houses looked stronger, and and often were in places where strength is not needed. However they often are lacking in critical areas.
Even the things you mention have changes: what about a ton of conduit runs for POTS lines that now seem quaint? Many of these, even if in conduit, aren't in locations where slapping an Ethernet jack makes sense. Duct work for fossil fuel furnaces is often undersized for heat pumps or AC that needs to flow a certain amount of air to function.
I'm OK with multi-decade life for certain things like roofs or fences or siding. But not for plumbing. What happens, one day the pipe just bursts and destroys the house?
Depends. PVC tends to fail catastrophicly so if you are nnot home to get the valve off you are in trouble (odds are you are home, as pressure changes from turning a faucet off are likely to cause this. Metal pipes develop slow leaks over time so if you look at the house monthly you will probably catch issues before they do too much damage. So long as PEX isn't exposed to UV is is probably good forever (but the joints
are not).
Floods generally will not destory a house structure but it will destory the drywall, carpet, and the like so the cleanup is expensive.
If only Uponor would flesh out their fitting portfolio for 3/8”. 3/8” PEX is a near-perfect material for hot water distribution to sinks and showers — jurisdictions seem to have settled on the 0-2gpm range for sinks and showers, and 3/8” PEX high velocity at moderate pressure loss at these flows, which is exactly what you want. [0] But Uponor has very limited 3/8” parts, and using their brass fittings in that small size makes me a bit uneasy due to potential erosion issues. Give me stainless steel or plastic, please, or at least something where the very narrow part that inserts into the 3/8” PEX tube is highly resistant to fast-moving hot water.
If you consider push-to-connect fittings acceptable, something like this could be very nice for connecting tubing to shower valves:
(3/8” is permitted by code, but not by the tables in the UPC - actual math is required.)
[0] PEX, unlike copper, tolerates fairly high velocity hot water. Copper has a delicate passive layer on the inside, and scrubbing it off will erode the pipe. The interior of a PEX pipe, is, drumroll please, just PEX, which is a rather tough polymer that is not going to be easily eroded away.
Both PEX-A and PEX-B require a separate tools (segment of the tool, or swappable tool head) to perform the pipe to fitting connection. In most cases, it’s easier to just upsize the pipe and have your final termination point be the size you need. I’d rather have very cheap 1/2 inch available than have slightly more expensive 1/2 and 3/8 inch. If needed anything that required the 3/8 in, I would just use copper because it’s likely a very small and isolated case.
For domestic hot water, for the connection from whatever part of the system stays hot (the header, the recirc loop, etc) to the fixture, the amount of time and wasted water needed to get hot water to the fixture is directly proportional to the volume of the interior of the pipe, and for a fixed length of pipe, it’s inversely proportional to velocity. So you want the narrowest pipe you can get away with. 3/8” PEX has about half the interior cross-sectional area as 1/2”. This means you get hot water about twice as fast. 3/8” PEX loses about 26 psi/100 ft at 2 gpm and much less at lower flow. If you have 40 psi water and you have a short-ish pipe, that’s usually fine. Or if you have higher pressure and a longer pipe, you’re still fine.
The issue here has that, while the 3/8” PEX is near-perfect for this application, the rest of the system is not amazing. Your sink is likely (sigh) “3/8 female compression”, aka non-standard 9/16 UNEF or so, but the flow rate is well under 2 gpm, so this isn’t a big deal - use whatever adapter you like.
But your shower likely has 1/2” NPT brass female threads. To get the benefit of 3/8” PEX, you need to adapt it at the shower.
> If needed anything that required the 3/8 in, I would just use copper because it’s likely a very small and isolated case.
No, don’t do that. From the horse’s mouth (this particular horse very much wanting you to use copper):
> To avoid excessive system noise and the possibility of erosion-corrosion, the designer should not exceed flow velocities of 8 feet per second for cold water and 5 feet per second in hot water up to approximately 140°F. In systems where water temperatures routinely exceed 140°F, lower flow velocities such as 2 to 3 feet per second should not be exceeded. In addition, where 1/2-inch and smaller tube sizes are used, to guard against localized high velocity turbulence due to possibly faulty workmanship (e.g. burrs at tube ends which were not properly reamed/deburred) or unusually numerous, abrupt changes in flow direction, lower velocities should be considered. Locally aggressive water conditions can combine with these two considerations to cause erosion-corrosion if system velocities are too high.
A 2.2 gpm shower head fed by 3/8” copper is out of spec.
I have personally seen copper tube fail when used with plain water at excessive velocity. It’s not pretty. Fortunately it was outdoors. Don’t do this inside your walls. Most vendors seem to think 8 ft/sec in PEX at 140F is fine, though.
> 3/8” is permitted by code, but not by the tables in the UPC
Can you elaborate on this please?
It takes 90 seconds for hot water to flow from my water heater to my kitchen in the winter. I’m not sure if I have 1/2 or 3/8 pex (I’d have to crawl under the house to check). I’ve been thinking of adding a small Bosch water heater under the sink or a recirculation like, but maybe I should reduce the size of the pipe too
Code will have requirements like "pipe must flow X gallons/min" or something - and then a table of pipes of various materials and if they meet the requirements at a given length.
But they don't list all possible pipes, or all lengths. And the argument is that 3/8 PEX will flow to requirements and have a smaller amount of water sitting in it.
> This is also the reason why pvc is super dangerous for compressed air.
Back in the day all us kids knew to get the ABS stuff when building our potato cannons. I was terrified of the combustion chamber shattering right next to my face.
I remember hearing the opposite, 20 years ago when I made one–that PVC was preferable to ABS because you couldn’t readily buy ABS with any sort of pressure rating.
It didn’t even occur to me that ABS pipe is pretty much only used for drainage and vents. I think it’s still probably decent to have unrated pipe tear smoothly rather than rated pipe—over pressured—shatter?
I guess the pro move is to either (1) fully characterize the amount of pressure made from a random shot of hairspray, then choose a PVC pipe to accommodate, or (2) put a larger ABS sleeve over the inner PVC combustion chamber to contain the shrapnel.
