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Trane® Outdoor Air Systems

Trane outdoor air systems can meet your performance and budget goals. Improve indoor air quality, energy efficiency and comfort.

Overview

Higher indoor air quality. Improved occupant comfort.

Our family of outdoor air systems provides a range of units to meet your performance and budget goals.

  • Able to condition 100% of outside air year round
  • Reduce latent loads
  • Enhance thermal comfort and improve energy efficiency throughout the building
  • Maintain your building’s indoor air quality
  1. PROTECT HEALTH OUTLINE - SVG

    Improved Occupant Comfort and Building Health

    Indoor air that’s too humid can result in occupant discomfort, mold and microbial growth. It also can shorten HVAC equipment life.

    Trane dedicated outdoor air units control dehumidification separately from the rest of the HVAC system. This independent operation ensures the optimal level of moisture in your indoor environment.

  2. SUSTAINABILITY OUTLINE - SVG

    Higher Energy Efficiency

    Both Horizon DOAS and Horizon Flex deliver dehumidification with a high level of energy efficiency.

    Horizon DOAS exceeds the minimum requirement from ASHRAE® 90.1, as rated by AHRI 920. Horizon Flex is certified to AHRI 340/360 standards and meets minimum EER and IEER efficiency standards.

  3. TARGET OUTLINE - SVG

    The Performance You Expect from Trane

    Trane has a long history of delivering high-performing, right-sized HVAC systems across a wide range of markets.

    Our industry-leading expertise is embedded into every Horizon DOAS and Horizon Flex units. So you can be sure that each unit will meet or exceed your application’s demands.

Outdoor Air System Offerings

Mixed Air Unit

The Trane ® Mixed Air Unit is an outside air unit that offers fresh air for improved indoor air quality and energy efficiency for your budget. The unit delivers up to 100% fresh air into your building and meets the ventilation requirements specified in ASHRAE ® 62.1. Mixed Air Unit meets minimum EER and IEER efficiency standards, which means it’s good for your budget and good for our planet.
Trane® Horizon® Flex™ delivers flexible, energy-efficient outdoor air

Horizon® Flex™ Outdoor Air Unit

  • Delivers up to 100% outside air with the flexibility to use less if desired
  • ≥ 51°F dewpoint for occupant comfort
  • Peak load humidity control
  • Lower first cost
  • ASHRAE 340/360 certified to condition air and provide thermal comfort to your space
  • Meets minimum EER and IEER efficiency standards
  • Double-wall insulation for efficiency and quieter operation

 

Horizon DOAS OAD6 DX Primary Front Left Angle

Horizon® Dedicated Outdoor Air Systems (DOAS Unit)

  • Configuration Options: With or without ERV, air-cooled, water-cooled, air-sourced heat pump, water-sourced heat pump
  • Heating Options: Electric, Hot Water and Gas
  • Scroll Compressors: Standard and Digital
  • Space Control: Single zone, multi-zone VAV, make up air
  • Voltage: 208v, 460v, 575v
  • Refrigerant: Next-gen, low-GWP R-454B

Product Literature

FAQs

Understanding DOAS design.

The Horizon family offers advantages to various systems, including VAV, VRF, water source heat pumps, fan coil units, and packaged terminal air conditioners (rooftop units). But how do you choose between a Trane Horizon DOAS and Horizon Flex unit?

Consider a DOAS when the primary focus is maintaining indoor HVAC air quality and precise humidity control. Trane Horizon® DOAS excels in critical applications that demand high air quality standards, such as labs, medical facilities, data centers, and manufacturing facilities. Its ability to precondition outdoor air and regulate humidity levels ensures a healthier and more comfortable indoor environment.

Alternatively, a mixed-air system like Horizon Flex offers a balance between performance and cost-effectiveness.

In most climates, the dedicated outdoor air unit should be sized to dehumidify the outdoor air to a dew point low enough to offset the space latent load and maintain space humidity at or below the desired limit. Conditioning outdoor air to a proper dew point creates a noticeable difference, making indoor air feel cleaner and fresher while preventing mold and harmful microbial growth.

The Horizon® DOAS achieves a dew point of ≥ 43°F at both full and part load. Trane’s Horizon® Flex delivers a dew point of ≥ 51°F at full load, maintaining balanced indoor humidity and energy-efficient ventilation.

Trane has experience designing DOAS solutions for a wide range of rigorous applications, including K-12 schools, higher education, manufacturing labs, data centers, medical facilities, high-end offices, multi-family housing, and hospitality.

Horizon Flex is used in a variety of applications as well, most notably education, commercial office space, and retail.

Trane’s Horizon® DOAS and industry standards.

The Trane Horizon® DOAS addresses the need for maintaining proper indoor air quality (IAQ) by effectively managing ventilation and humidity. This is important as most Americans spend nearly 90% of their time indoors, where buildings serve as refuges from extreme weather, excessive humidity, and unhealthy air quality. However, improving IAQ is just one aspect of a broader concept known as Indoor Environmental Quality (IEQ). Trane’s outdoor air units also contribute to overall IEQ by:

  • Optimizing Ventilation and Controlling Humidity: The Horizon® DOAS supplies fresh outdoor air to dilute indoor pollutants and reduce contaminants like VOCs and CO2, while effectively controlling humidity to prevent mold growth and maintain comfort.
  • Enhancing Thermal Comfort: Integration with HVAC systems allows these units to maintain consistent indoor temperatures, contributing to a comfortable environment. 
  • Energy Efficiency: Efficient operation of ventilation and humidity control systems reduces energy consumption, leading to a more sustainable building operation.

ASHRAE 62.1 and AHRI 920-2020 are the baseline. ASHRAE 62.1 is the standard for ventilation management and AHRI standard 920-2020 created a standard definition and performance measures for DOAS equipment. Trane DOAS sets new standards for humidity and air conditioning ventilation management:

  • Energy Efficiency and Sustainability: Trane’s Horizon DOAS preconditions up to 100% outdoor air, reducing the load on central HVAC systems. By decoupling latent and sensible load management, the central HVAC systems can be properly sized, leading to overall improved system energy efficiency.
  • Humidity Control: The Horizon DOAS is engineered to manage humidity levels effectively during peak and off-peak, preventing the growth of mold, mildew, viruses, and other hazardous organisms. By conditioning outdoor air to the proper supply air dew point, at full and part load conditions the system ensures that indoor air feels cleaner, fresher, and healthier to occupants.
  • Low Global Warming Potential Refrigerants: All Trane equipment, including the Horizon DOAS, uses refrigerants with low GWP, supporting sustainability and reducing carbon emissions.

The Horizon® Flex is also AHRI 340/360 certified and ASHRAE 90.1 compliant, ensuring it meets industry standards for performance and efficiency.

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