I am interviewing contractors to replace my air and furnace and are getting conflicting messages on the converting from my current system (Carrier EN038) series from 1985 to an R-410A based system. More specifically, I have heard that you can flush and drain linesets as long as the tubing is flexible and the joints are hard soldered and the issues are with hard copper tubing linesets. Then I have also heard that it is not a good idea to ever re-use line sets whether they are hard tubing or flex tubing. Sorry, I may be off in my terminology as I am just a novice. Any Insight?