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DOAS - Dedicated Outside Air System


A dedicated outdoor air system (DOAS) is a complete, unified unit that is designed to meet a wide range of heating, cooling, dehumidification, and ventilation requirements.

These units deliver up to 100% outside air and are ideal for any variable air volume (VAV) or dedicated outdoor air system (DOAS) application.

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Key Takeaways

Table of Contents

What is a DOAS?

Dedicated outdoor air systems pre-condition 100% fresh air separately before distributing it inside, optimizing temperature, humidity, and filtration specifically for the air occupants breathe. DOAS pairs well with other HVAC approaches, enhancing building health.

How it Works

The turnkey system features a total enthalpy wheel that spins between two air streams while moving energy that is both latent (moisture) and sensible (heat). The enthalpy wheel, which offers up to 80% total efficiency, greatly reduces the heating and cooling capacity requirements, resulting in lower operating costs.

A DOAS is built from the ground up to save energy and reduce operational expenses. With its rare earth magnet inverter, the scroll compressor terminates excessive cycling and hard starts that extend the unit’s life.

It can achieve optimal efficiency in part-load settings with the help of the latest modulating technology.

It has optional hot gas reheating components and fully regulating refrigeration that can deliver the precise air volume needed at the required temperature and humidity. Thanks to variable speed components, the unit can alter its heating and cooling capacity to match the necessary load.

This provides a consistent temperature throughout the space and avoids the large temperature swings often associated with single-stage equipment.

DOAS restaurant diagram benefits dedicated outside air system food service
Authorized DOAS Suppliers

We are the authorized distributors for the leading American manufacturers of DOAS units. We’ll gladly provide the ideal unit for your application as authorized representatives.

For a fast quote or if you have inquiries about commercial or industrial DOAS, get in touch with us.

DOAS Manufacturers

We are official representatives of the DOAS manufacturers listed below. Click the link to learn more about the manufacturers’ warranties and other information.

absolutAire Distributor

DOAS Control Variables

The unit can be calibrated for 100% outside air or partial recirculation, providing tempered air. When set to partial recirculation, the fan operates at a constant speed; however, the damper modulates the outside air intake depending on how the kitchen hood operates.

Custom Design Options

Depending on your needs, a custom DOAS can be made for your application’s needs, including:

Choice of Condensers

  • Water source heat pump
  • Air-cooled
  • Water cooled

Heating Options

  • Electric
  • Gas
  • Heat pump mode
  • Steam coils or hot water


DOAS units provide 100% OAU and are ideal for more applications. They offer more extensive tonnage ranges and nominal CFM than competing units.


Accessibility and safety are now easier than ever, thanks to a hinged access door and touch-safe control panel.


Galvanized steel cabinet panels exceed 1000 hours of salt spray testing and have a two-coat primer and primer-paint external finish.


Listed below are the range and variations of DOAS units. Contact our official representative to find out which model best suits your application.

DOAS for Commercial Kitchens & Food Service Industry

DOAS units provide energy-efficient solutions for commercial kitchens that require fresh air from outside to be tempered before entering the space, vastly improving indoor air quality (IAQ).

Our industry-leading, energy-efficient Dedicated Outdoor Air Systems (DOAS) are the perfect solution for commercial kitchens requiring more outside air. Air should also be fully conditioned for complete temperature and humidity control inside your kitchen and dining spaces. 

Buildings that don’t follow codes with improper ventilation can cause health hazards for guests and staff (source).

Ensure you work with a trained professional when selecting the best DOAS unit suitable for the building.

DOAS vs. HVAC Unit

The drawback of adding outdoor air to your building is that it may increase humidity indoors.

If the additional moisture is not controlled, it may foster the growth of viruses, mold, mildew, and other potentially dangerous organisms. Controlling the amount of moisture in the building is essential for preventing these byproducts from forming.

A typical HVAC air conditioner is designed with temperature change in mind and may not be able to handle the additional moisture content

Yes, an HVAC air conditioner does remove some humidity from the air, but most are designed to regulate temperature and not to remove moisture effectively. Instead, a system that can fully regulate temperature and humidity must be implemented.

Restaurant Design With Make-Up Air (MUA) And Rooftop Unit (RTU)

Typically, an RTU exhausts the air, and an MAU exhausts up to 80% of the air from the kitchen hood. The RTU must exhaust and make up the rest of the air in the kitchen. There are limitations on the capacity of outside air they can handle.

The diagram shows a commercial kitchen in a small restaurant or fast food chain.

restaurant ventilation make-up air and roof top diagram

DOAS for Restaurant Diagram

The diagram below demonstrates how a DOAS unit can combine the roles of an RTU and MUA in one unit. The unit also eliminates moisture before entering the kitchen, whereas a typical kitchen attempts to control it afterward.

DOAS restaurant diagram benefits dedicated outside air system food service

Advantages of DOAS for Restaurants

Common Food Service Applications