Overview
Combined air handling units are assembled by joining modular functional sections, each dedicated to a specific task in the treatment of supply air. Together they filter, heat, cool, humidify and deliver conditioned air to the space.
Key functional sections
- Return air section connects to the return duct and is fitted with a multi-blade volume damper on the top or side.
- Fresh air or mixing section receives outdoor air from the top or side and blends it with return air.
- Pre-filter section uses non-woven panel or bag filters to remove dust and solid particles, keeping coils clean.
- Heating section comes as steam, hot-water or electric type; electric heating is common in constant-temperature, constant-humidity units.
- Cooling coil section contains finned-tube heat exchangers and a condensate pan; a baffle turns it into a cooling and mist-eliminating section.
- Humidification section applies dry steam, high-pressure spray or wet-film humidifiers.
- Supply fan section uses double-inlet centrifugal fans with vibration isolation; the supply section sets outlet direction and links to the duct.
- Medium or sub-HEPA filter section raises air purity, while the silencer section cuts airflow noise with plate or perforated attenuators.
- Intermediate section provides maintenance access, and the energy-recovery section exchanges heat between supply and exhaust air through plate-fin cores.