Ventilation is an essential part of any building—homes, offices, clinics, or commercial spaces.
However, many people struggle with understanding the differences between common systems such as propeller fans, sirocco fans, and energy-recovery ventilators.

This guide explains the basics of each type and how to choose the right one for your space.

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1. Propeller Fans (Wall-Mounted Ventilation Fans)

Features

• Installed directly on exterior walls
• Air is exhausted straight outdoors by fan blades
• Common in home bathrooms, toilets, and small kitchens

Advantages

• Low cost
• Simple structure, easy maintenance
• Strong airflow—effective for removing heat and humidity

Disadvantages

• Affected by outdoor wind pressure
• Not suitable for rooms far from exterior walls
• Limited installation locations

Best suited for

• Residential toilets and bathrooms
• Small restaurant kitchens
• Storage rooms or back-of-house areas
• Spaces with an exterior wall available for installation

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2. Sirocco Fans (Duct-Type Ventilation Fans)

Features

• The most common ventilation system in commercial interiors
• Uses ducts to exhaust air through ceilings or walls
• Cylindrical fan with many curved blades (sirocco type)

Advantages

• Can install ducts along any route (high flexibility)
• Works well even with long duct runs
• Quieter than propeller fans
• Can be concealed in ceilings for a clean interior look

Disadvantages

• More expensive than propeller fans
• Requires duct installation
• Maintenance requires a ceiling access panel

Best suited for

• Offices, shops, and clinics
• Commercial restrooms
• Kitchens where direct wall exhaust is not possible
• Any space with a long duct route

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3. Energy Recovery Ventilators (ERV / “Lossnay” Systems)

Features

• Provide both supply air and exhaust air simultaneously
• Recover indoor heat and moisture while ventilating
• Improve indoor comfort and energy efficiency

Advantages

• Reduce heating and cooling loss
• Keep room temperature more stable
• Very quiet operation
• Ideal for high-performance buildings

Disadvantages

• Higher initial cost
• Requires dedicated installation space
• Filters need regular maintenance

Best suited for

• Offices and clinics
• High-insulation residential buildings
• Spaces where comfort and energy efficiency are important

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4. Which Ventilation System Should You Choose?

Residential Toilets → Propeller Fan (Wall-Mounted)

Simple, inexpensive, and effective as long as the toilet faces an exterior wall.

Commercial Toilets → Sirocco Fan (Ceiling-Duct Type)

Most commercial toilets are not located on exterior walls, so duct ventilation is required.

General Stores & Offices → Sirocco Fan

Offers flexibility and stable performance.

Spaces Requiring Quiet, Comfortable Airflow → ERV

Useful in clinics, offices, and modern residences.

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5. Summary

Each ventilation method has strengths and ideal applications:

• Propeller Fan: Direct exhaust, strong airflow, low cost
• Sirocco Fan: Most versatile, duct-based, cleaner installation
• Energy Recovery Ventilator: Best comfort and efficiency

Understanding these differences helps you plan ventilation more effectively for both renovations and new constructions.

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【Required English Disclaimer】

This article provides general information for educational purposes.
Actual building conditions vary depending on structure, design, regulations, and equipment specifications.
Always consult licensed HVAC professionals or building engineers when designing or modifying ventilation systems.