My contractor installed PEX tubing in my basement for the supply and return lines connected to my Burnham boiler. The install was done in the late spring, so I guess he didn't expect the tubing to expand so much once the heat kicked on. Right now, I have two really bad sagging spots. One is about an 8' stretch where the low point is about 1' from the bottom of the joist. The other is also about 8' long with the low point about 18" from the bottom of the joist. There are also a few curves that I plan on straightening out and inserting 90 degree elbows.

So my questions:

1. How do I know how much I can safely cut from the sagging PEX before I reattach to the joists? Do I just wait for the summer to see if the tubing contracts and then bring the tubing up with a few inches of slack?

2. Is adding a right angle or two to each line bad idea or is it highly preferred to have continuous tubing?