Trane® / Mitsubishi Electric CITY MULTI® VRF
Featuring an innovative two-pipe system, Trane® / Mitsubishi CITY MULTI VRF units offer options for air and water-source heat pump or simultaneous heat/cool systems.
Learn moreHorizon® Family
Trane® Outdoor Air Systems
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
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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.
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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.
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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.
A Family of Solutions
Horizon® Dedicated Outdoor Air System
Trane’s Horizon Dedicated Outdoor Air System (DOAS) is ideal for buildings with high-performance requirements. It helps improve indoor air quality (IAQ) to keep your building optimized and your people comfortable.
Horizon DOAS units eliminate excess moisture, preventing the health risks associated with mold and microbial growth. The unit conditions 100% outside air year-round and reduces latent loads. These functions enhance the entire building system's comfort, energy efficiency and overall health.
Horizon® Flex™
Application-Specific Outdoor Air System.
Not every building requires 100% outdoor air or a very low dewpoint, so why invest in more equipment than you need? Horizon Flex unit can deliver 100% outdoor air. Many customers need more than a standard unit provides but less than 100% outdoor air for their application. The Horizon Flex the ideal choice for lower upfront costs.
Product Literature
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Horizon® Dedicated Outdoor Air System Family Brochure
DOAS-SLB001-EN
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Dedicated Outdoor Air Systems Application Guide
SYS-APG001-EN
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Understanding DOAS Design
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
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.
Related Products
Indirect Fired Make-Up Air
Trane indoor make-up air handling units are designed for applications that need heating, cooling, ventilation, and make-up air. They are gas-fired and work indirectly.
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Horizon™ Water-Source and Air-Source Heat Pumps
The Trane® Horizon™ Dedicated Outdoor Air Units offer Water-Source Heat Pumps and Air-Source Heat Pumps. These are two of the most sustainable and eco-friendly methods for heating and cooling buildings.
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