All brands of Pex are interchangeable, there 2 types of bands: 1) bronze rings that are swaged on and 2) stainless steel bands that "ratchet" on they both work the same but use very different tools, and some local government require one or the other. There is a 3rd system for connecting Pex, I have only seen it on TV, you expand the Pex and slide a different size fitting in and it will shrink back on the fitting (in a number of hours.) This seems to be the best choice for hot water heat applications, but will work for all other plumbing too.
Fittings come in plastic or brass and are also completely interchangeable.
Tools: The crimping tool I use looks like a bolt cutter and will do 3/8, 1/2, & 3/4 sizes of Pex, but needs checked/adjusted when changing sizes! There are 1/4 and 1 inch Pex also and will require a separate tool each. The clamping tools for stainless bands are totally unrelated so they will be more money (Pick one system and stick to it!)
My son had his home in South East Texas re-plumbed with Pex. It took the pros longer to remove the old copper, that to install the new Pex! Total time was a day and a half. CPVC is cheaper but takes longer, New copper would be 3 or 4 times as expensive and 2 or 3 times more labor than Pex!
There is Shark Bite Brand of Pex and fittings, but don't confuse that with Shark Bite Type plumbing connectors! The cost difference is huge!!!
Pex can freeze! but it takes a little colder and a little longer because of the better insulating nature of the plastic. But when a line does freeze the tube can expand up to 3 times without breaking, but the fittings are subject to the limits of plastic or brass!
Coming off any hot water tank, including tankless, you need 18-24" of copper pipe on the inlet and outlet sides, it is a safety thing required in many states (and a good idea everywhere). Since you are redoing the copper and the new Tankless water heater is electric, start by placing the water heater in the center of your usage. For example, between the bathroom and kitchen or kitchen and laundry. That way you have less water line with cold water in it, that saves water and heating energy every time you wash your hands. It can be in a hall closet or under/inside a kitchen cabinet, just leave room for service, and if the tank requires a "overflow" line to a drain.
If the old lines are 3/4 size instead of 1/2 (copper size, not inches!), you can often use old plumbing holes to pull the Pex through like an electric wire. You won't have to rip out all the walls when you can do that. So an Electrician's "fish" is a tool that you can buy, rent, or borrow to help with that. If you are going to take longer than a day, you can plan ahead and rough in the Pex and disconnect the old copper in sections of the house, so you aren't completely without water for too long. I recently did a 200 year old home's plumbing, in just the basement. I took out over 400' of 4 kinds of pipe (of several sizes) and used 110' of 1/2" Pex. Between the new pipe, and removing all the unnecessary zigzags, the pressure to all the faucets was at least double.
Tip on doing the job. Buy lots of extra fittings and around double the ferrules (bronze rings). Then return the unopened parts when complete. This sure beats running for one last part-- two or three times! Lowe's and Home Depot both stock the common parts and tube, but you'll not get the best price!
Ivan
