A free cooling coil transfers heat directly from a building or process to outdoor air when ambient temperature is sufficiently low, eliminating mechanical cooling equipment runtime. These coils enable significant energy savings during winter and shoulder seasons in temperate climates.
System Integration
Free cooling coils connect to building water loops, allowing outdoor air to cool circulating fluid without operating compressors. Controls monitor outdoor temperature and building return water temperature, automatically activating coils when outdoor conditions provide sufficient cooling capacity. Typical activation occurs when outdoor air drops below 55°F. These systems eliminate cooling costs during operation periods, potentially reducing annual HVAC energy consumption by 20-40% in favorable climates.
Design Considerations
Free cooling coils require freeze protection in freezing climates, typically using glycol solutions or heat tracing. Stainless steel or aluminum construction prevents corrosion from outdoor air exposure. Coil selection depends on building loads, ambient temperature data, and occupancy patterns. Installation costs average $3,000-8,000 per building depending on complexity. Expected service life reaches 15-20 years, with maintenance limited to seasonal inspections and occasional cleaning.