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What Is a Dedicated Outdoor Air System (DOAS)?
A Dedicated Outdoor Air System (DOAS) is a ventilation system designed to deliver 100% outdoor air to a building while independently managing humidity and ventilation loads. By separating fresh air delivery from heating and cooling equipment, a DOAS improves indoor air quality, reduces system strain, and supports more stable temperature control across the facility.
Engineered Temperature Solutions designs DOAS systems to integrate seamlessly with rooftop units, fan coils, VAV systems, and other HVAC equipment, ensuring ventilation is properly controlled without sacrificing efficiency or comfort.
DOAS systems are especially effective in commercial environments where consistent airflow, humidity control, and ventilation compliance are critical, making them a foundational component of modern HVAC system design.
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Purpose-Built Ventilation
DOAS units are designed specifically to manage outdoor air requirements, delivering consistent ventilation without relying on space conditioning equipment to handle fresh air loads.
Humidity Control First
By actively conditioning incoming outdoor air, DOAS systems remove excess moisture before it enters the building, improving comfort and reducing the risk of condensation, mold, and indoor air quality issues.
Reduced HVAC System Load
Separating ventilation from heating and cooling allows fan coils, RTUs, and VAV systems to focus on temperature control, improving efficiency and extending equipment life.
Designed for Code Compliance
DOAS systems help commercial buildings meet ventilation and indoor air quality requirements while maintaining predictable airflow and performance across all occupied spaces.
Our Services
ETS provides complete Dedicated Outdoor Air System (DOAS) services, supporting every phase of system performance.
🚩DOAS Red Flags
When Should You Service or Repair a DOAS System?
Key Indicators Your DOAS System Needs Attention:
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Inconsistent or insufficient outdoor airflow
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Persistent humidity or moisture issues
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Odors or stale indoor air
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Condensation at diffusers or ductwork
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Comfort complaints despite normal temperatures
DOAS issues often show up as humidity, air quality, or ventilation complaints long before the system fully fails.
Airflow Imbalance
Inconsistent outdoor airflow often points to damper, control, or balancing issues within the DOAS system.
Poor Humidity Control
Ongoing humidity problems typically indicate improper dew point control or reduced moisture removal capacity.
Ventilation Quality Issues
Odors or stale air can signal inadequate outdoor air delivery or filtration performance.
Condensation Formation
Moisture at diffusers or ductwork is commonly caused by airflow misalignment or insufficient dehumidification.
Ventilation-Related Comfort Complaints
Comfort issues despite proper temperatures usually stem from ventilation imbalance rather than heating or cooling failure.
Every Ventilation Need.
One Reliable Team.
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ETS HVAC Insights
Go inside our commercial HVAC projects and discover how ETS helps Central Ohio businesses upgrade systems, solve problems, and improve building performance year-round.
Frequently Asked Questions
A Dedicated Outdoor Air System is designed to deliver 100% outdoor air to a building while independently managing ventilation and humidity, separating fresh air loads from heating and cooling equipment.
DOAS systems solve ventilation and humidity challenges by providing controlled outdoor air without overloading rooftop units, fan coils, or VAV systems.
Unlike standard RTUs, a DOAS system is purpose-built for ventilation and humidity control rather than space heating and cooling.
A DOAS focuses on delivering code-compliant ventilation and humidity control to occupied spaces, while makeup air units are typically used to replace air removed by exhaust systems and maintain building pressure.
DOAS systems are commonly used in offices, healthcare facilities, schools, fitness centers, hospitality spaces, and other buildings with high ventilation and IAQ requirements.
DOAS systems actively condition incoming outdoor air to control moisture levels before it enters the building, helping prevent condensation, mold, and comfort issues.
Yes. DOAS systems are designed to integrate with existing RTUs, fan coils, VAV systems, and building automation systems.
A DOAS system typically includes outdoor air intakes, filters, cooling and heating coils, fans, controls, and duct connections to distribute conditioned air.
While not always required, DOAS systems are often used to meet ASHRAE 62.1 ventilation standards and local building code requirements more effectively.
Key benefits of a DOAS system include:
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Improved indoor air quality
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Better humidity control
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Reduced load on primary HVAC equipment
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Improved comfort consistency
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Enhanced energy efficiency
DOAS systems can improve overall HVAC efficiency by allowing heating and cooling equipment to focus on temperature control rather than ventilation loads.
Routine maintenance includes filter replacement, coil cleaning, sensor verification, condensate management, and control calibration.
Common DOAS issues include airflow imbalance, humidity control problems, sensor failures, control sequencing errors, and drainage issues.
Yes. When properly engineered, DOAS systems are well-suited for Ohio’s humid summers, cold winters, and wide seasonal temperature swings.
Yes. Engineered Temperature Solutions provides full DOAS support, including system design, installation, maintenance, and repair for commercial buildings across Ohio.
Need DOAS services in Central Ohio? Request a quote or call (614) 289-8733 to get started.
Frequently asked questions
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