One of the things I like about it is that because it's flexible, if you route it carefully you can avoid using connectors in a lot of areas that rigid pipe would require a joint. The way I saw it used, the only joints were in areas like cleanout access and crawlspaces, so even if a joint went bad, it wouldn't require opening up a wall to fix. I'm not a pro, so maybe rigid pipe is supposed to only have joints in accessible areas too, but that certainly wasn't the case with the century-old plumbing I saw.

It's still relatively new compared to other pipe material, so there may be some other surprises that crop up with long term use, but I'm really impressed with its ease of installation.

One thing about plastic pipe is that it is susceptible to rodent damage, unlike copper.

Seen it a few times.

There is few type of PEX fitting systems. I agree the hose clamp style doesn't inspire confidence at all.

I have replaced almost all piping in my house. I used PEX-B with the fittings secured by copper rings that you crimp with the appropriate tool. It is so easy to use and confirm the joint with a gauge tool.

I had to solder copper where I couldn't replace it all. Every copper joint was it's own little project. While for PEX it's quick and easy.

After a thorough session of Internet Research, I chose to start with stainless cinch rings rather than the copper crimp rings? Because copper crimp rings are seemingly preferred by professionals only due to being slightly cheaper in quantity plus looking nicer? Also the consumer-priced power tool (Ryobi) for doing the crimp rings has mixed reviews, while their cinch ring tool seems universally loved (likely due to manufacturing tolerances needed for a good crimp die).

Either way, my lack of confidence applies to all PEX-B and PEX-A connections. They're all essentially a straight friction fit with some hose barbs. I got some PEX-AL-PEX fittings/tube too (the 1" P-A-P has 35% larger cross section than plain PEX, and PEX larger than 1" seems rare and expensive), and the threaded compression style gives more confidence.

I'm not disputing that PEX is a whole lot easier, even knowing how to do copper and just watching PEX videos. As I said, "maybe I'll fall in love". I'm just starting with piping where a leak won't be a major hassle (hydronic, and eventually compressed air), and foresee myself continuing to do copper for any modifications to potable water in the immediate future. If I had to redo the whole house, I'd get over my reservations quick!

PEX-AL-PEX is more expensive, but also convenient to work with as it stays in place like a gooseneck lamp. It is also an oxygen barrier, and as such useful for closed loop hydronic with prone to rust components (cast iron). I don't know if P-A-P can be rated for potable water though.

I purposefully avoided the stainless cinch rings. This feels like the cheapest solution to me. It has some moving pieces. I found examples of leak with stainless cinch rings online when I was choosing what technology to use. Not so much with the copper rings. The copper rings are just that. A thick copper ring that you press into shape with great force. The price of the $50 crimp tool is nothing compared to the cost and hassle of a leak down the line. Add a $30 ring cutter tool too. For when you mess up (you cannot remove the ring in place, you must cut the pipe).

I have also retrofitted the house with underfloor hydronic heating. 400m of PEX in an open loop system. Not a single leak after few years.

With the copper rings the PEX takes the shape of the fitting. Even if you manage to cut the ring. The PEX won't come off. You have to cut the pipe lengthwise to get it off. I am not sure the stainless clamps perform the same.

Why open loop for the radiant? Already had non-barrier PEX? Or using existing DHW as the heat source?

I'm installing an outdoor wood boiler, which is an open system. But it will have a heat exchanger to my closed hydronic system for house distribution.

P-A-P seems nicer to route the pipe, but there are fewer fitting shapes. I'm considering it for a few long runs, because anything over 1" nominal seems to become rare and jump in price, and the 1" P-A-P is 35% larger than 1" PEX-B. But maybe I should just suck it up and deal with 1.25 or 1.5 inch PEX-B. (Would you happen to know a good source? I keep coming up with Supplyhouse.com, but half the fittings are out of stock and they seem expensive).

I'll see how I like the cinch rings. Maybe I'll move towards the crimp rings down the line. I figured a powered tool would be a boon for doing a bunch, and as I said it seems like for a powered crimp ring thing I'd need a Milwaukee cordless for ~$600, whereas the cinch ring I can get away with a $100 Ryobi. I can justify the latter for personal use, but not the former.

pexuniverse and supplyhouse are the two places I have used for the material.

Open loop is easy to deal with. I can use the same water heater. It's the bay area in California, so the system works for 1/3 or the year. Rest of the time it's simply buffering the cold water supply to the water heater. So no water stagnating, not air vent needed, and it's always filled up by definition. Further more because it's at the street water pressure, the pump cannot cavitate, so it last longer and is quieter.

I only used manual tools to crimp the rings. Sure you need some force but your body will build muscles. And since PEX is flexible you don't use that many fittings anyways. It's really childs play.

Can you tell me more how you retrofitted your house with underfloor hydronic heating? How long did it take and what materials did you use. How many pipes per square meter? Also, did you reuse the flooring after or did you replace it completely?

I'm looking into adding underfloor heating myself.

The house is a stick framing atop a perimeter foundation, with few posts making a crawl space. You can almost sit down. It took a week to install loops of 1/2 (16mm) PEX between the joists supporting the floor. The pipes go through holes in the joist and blocking, and cross at the beginning of every bay to make up every loop. The PEX is held up by aluminum heat plates that are simply stapled. Theost annoying part of the job was to cut all protiding nails. The took few days prior the piping. There is something like 400m of pipes. Split into multiple circuits. Aligned at room boundaries and adjusted to have similar length for homogenous pressure drop. All of that is an open loop with the water heater. A pump, a thermostat and few check valves supply the manifold that distribute the hot water under the floor.

Awesome, thanks. The loop design looks simple, which is encouraging. It's true that the most annoying parts are usually the secondary tasks that can't be ignored either way.

The joists sure help. In my case the floor is either tiles or wood panels laying on top of poured concrete.

Be sure to read up on oxygen barrier vs permeable Pex. (You probably already have, but if not, you almost certainly want barrier Pex in a closed-loop system.)

I haven’t seen 100 psi in household applications

My city water pressure was around there, with few ill effects. I've since installed a pressure regular to drop it to around 60psi. But I liked it better before, especially on the silcocks.

It's not really the pressure that has me worried, but rather the potential flow rate. I've dealt with a flooded basement before, and I'd rather not do it again.

I don't see many people complaining that PEX fails by completely pulling apart, but it's hard for my intuition to accept that.