A sub-cooling coil is an extra section of the condenser that drops the refrigerant temperature well below the saturation point for higher efficiency. This hardware advantage allows our Penta-Zone systems to maintain incredible cooling power even on the hottest days of the year. In a Bravo Milano 18,000 BTU Universal Floor/Ceiling unit, this translates to a faster "chill factor" when you first turn the system on. To keep this coil performing at its peak, mounting the condenser on a Ground Stand ensures it stays clear of dust and lawn debris. Proper line-set lengths from our Installation Kits are necessary to take full advantage of this sub-cooling effect. For those looking to maximize their energy savings, this feature is one of the most important technical specs to consider. It represents the high-end engineering found across the entire Bravo Milano catalog.