If your RV water heater does not have a built-in heat exchanger but you still want to install a freeze protected (closed loop) system this kit is for you. It contains everything you need to add a high quality freeze protected solar water heater to your RV. Included is a compact stainless steel heat exchanger (316 alloy) and all other parts required for a closed loop system. The antifreeze in the solar loop is heated by Heliatos SW-38 solar water heating panel. This panel is robust enough to be mounted on a vehicle at highway speeds, has unbreakable twinwall polycarbonate glazing, and a strong aluminum frame, yet only weighs 12 lbs.