Can An AHU Also Provide Heating Functionality?

Can an AHU also provide heating functionality?

Yes, an Air Handling Unit (AHU) can absolutely provide heating functionality. In fact, heating is one of the core air-conditioning capabilities of most AHUs, making them versatile components in comprehensive HVAC systems that handle both cooling and heating needs.

How AHUs Provide Heating

AHUs integrate heating components to warm air before distributing it through a building’s ductwork. The key elements involved are:

Heating Coils

AHUs are equipped with heat exchange coils (similar to cooling coils but designed for heating). These coils transfer thermal energy to the air passing over them.

External Heat Sources

Unlike standalone heaters that generate heat independently, AHUs typically rely on external sources to supply warmth to the heating coils. Common sources include:

Hot water or steam from a central boiler (via pipes connected to the AHU’s coils).

Hot gas from a chiller or heat pump in reverse cycle (for heat recovery).

Electric resistance heaters (less common in large systems due to higher energy costs, but used in smaller or temporary setups).

Air Mixing & Distribution

The AHU blends recirculated indoor air (often pre-filtered) with fresh outdoor air in a mixing chamber. This combined air then passes over the heating coils, where it absorbs heat, before being pushed by fans through ductwork to heated zones.

Why Heating is Integral to AHUs

AHUs are designed to "condition" air comprehensively, which includes not just cooling, filtering, or humidifying, but also raising air temperature to maintain comfort. This is especially critical in:

Cold climates: Where buildings require consistent heating during winter.

Large commercial/industrial spaces: Such as offices, hospitals, or factories, where uniform heating across multiple zones is essential.

Multi-seasonal operation: AHUs switch between heating and cooling modes based on outdoor temperatures or thermostat settings, often controlled by a Building Management System (BMS) for efficiency.

Key Difference from Standalone Heaters

Unlike space heaters or radiators that heat specific areas, AHUs provide centralized, duct-distributed heating that integrates with other air treatments (filtration, humidity control). This ensures heated air is clean, properly humidified, and evenly distributed across the entire building, rather than creating isolated hot spots.

In summary, heating is a standard and essential function of most AHUs, making them versatile units that handle both cooling and heating to maintain comfortable, healthy indoor environments year-round.