Crown Boiler’s OC System is a control option for its Aruba 4 and Freeport 2 boilers. This control is designed to simplify the installation, operation and service of the boiler system and save energy. It launches with three plug-in OC Cards to control different boiler functions — outdoor air reset, low-water cutoff and high-limit reset. These cards plug into the OC Panel to make up the system, which then fits onto the boiler.