Of stove building events

This copper tubing needs to make way for the flu. (It’s part of the bench and radiant floor heating system, lurking just above the flu pipe in the bowels, scrubbing heat and moving it to the floor.)
Two loops tucked perfectly, one is trying but blocked by another that isn’t long enough to go around the new flu pattern. (The original flu ran horizontally into the water heater.) In my plumbing department I found three brass flare/compression parts for the job, though introducing a 90* elbow isn’t ideal. It’s free and not a big deal.
Shall I cut it now while I have a couple hours before work? The heating system is full of fluid and could be a lil messy, especially as glycol is sticky. Fortunately the top of the system (by the water heater and reservoir) isn’t full, and the tube I need to cut is above the floor, so it won’t be THAT messy…