do I just cap the closed loop off? do I need to drain it before capping? i have a waterfurnance with a QT Flow Center 1-230qfc-g thanks for any suggestions
Only as a last resort. Most people would wish to do the opposite - go to closed loop from open loop. But that being said, leave it accessible after cutting. At the very least one could use the pipes as sleeves for something in the future. If you don't want to fuse a cap on them, just use a Philmac or rubber sewer cap fitting to seal them up.
This is surely not the norm. As stated above, it’s typically open to closed conversions. I’ve only seen 1 person go closed to open, and that was a large addition added to a house and the new field was not feasible for the homeowner. Open loop was was cheaper and he needed a new water too.