Air Intake Outlet

Overview

Engineering reference data for Air Intake Outlet in HVAC systems.

Key Formulas

Sensible Heat

$Q = \dot{m} c_p \Delta T$

Heat causing temperature change.

Latent Heat

$Q = \dot{m} h_{fg} \Delta\omega$

Heat causing moisture change.

COP (Cooling)

$COP = Q_c / W$

Coefficient of performance.

Variables

Air Intake Guidelines

• Intakes should be at least 0.15 m (0.5 ft) above the terrain.
• In areas with traffic, the intake should be at least 5 m (16 ft) above the terrain.
• The distance between intake, firewalls, and surrounding buildings must comply with local authority rules.
• Avoid short-circuiting intake air with used outlet air.
• Locate the air intake to minimize wind influence on system pressure conditions.
• Air velocity through intake openings should not exceed 2.5 m/s (~500 ft/min).

Air Outlet Guidelines

• Outlets should discharge directly into an unrestricted area.
• Avoid short-circuiting with intake air, window openings, or residential areas.
• The distance between outlet, firewalls, and surrounding buildings must comply with local authority rules.
• Locate the air outlet to minimize wind influence on system pressure conditions.
• Air velocity through the outlet should be between 3–15 m/s (~500–3000 ft/min).

References

• Original Source

Quick Reference: Design Parameters

The following table summarizes the key design parameters for air intake and outlet systems:

Wind Influence Considerations

Both air intakes and outlets must be positioned to minimize wind-induced pressure fluctuations within the system. Key considerations include:

• Avoid locations prone to turbulence (e.g., building corners, roof edges)
• Account for prevailing wind directions in the installation site
• Consider wind barriers if necessary to stabilize pressure conditions