I am adding a water softener to my house. Unfortunately the copper pipe splits in my finished basement and the outside faucets are all plummed together with the rest of the house. The water line comes into the basement in a bedroom closet. It runs into the center of the house into the area where the ducting runs. I cut an 8″x14″ hole and fished a string to the furnace room and into another unfinished room on the opposite side of the house. I can see the outside faucet in the furnace room and I will add a new one on the other side of the house. I will cut the input line where it tees and cap it. I then plan to add a tee and run the outside water into the furnace room and into the other room for the outside faucet and kitchen sink for drinking water. The issue is that I can pull PEX tubing through the ceiling but I will have a 26′ and 14′ span with no hangers. The PEX will sit on the basement ceiling in the duct area until it reached the rooms where a have access. Is this an issue? Should the PEX be wrapped?

Water pipes running in ducts is an issue and a bad idea. Running water in any type of pipe will get the outtter surface of the pipe to sweat, especially when air runs through the duct. This will set up a perfect environment for mold and mildew in the worst possible place in the home, the air ducts.

I am not running the water lines in the actual duck work. The water lines are already in the same boxing. I am just going to run an additional line in that boxing. The copper is attached to the joists but the new PEX line will just be sitting on the bottom of the boxing with no fasteners

So this is more of what we call a chase. Chases are used like a passage to allow wiring, ductwork or plumbing pipes to run unimpeded.

Right, so I fished a string down to both ends of the chase. On end is at the furnace room and the other is a work at the opposite side of the basement. I can pull the PEX tubing through but it will be laying on the bottom of the chase with no fasteners. Will this cause a problem with the PEX over time.

Pex will move slightly when water is turned on and off. There would be some very marginal friction wear but I don't thionk I'd lose any sleep.