DOAS Unit- Dedicated Outdoor Air Systems
A dedicated outdoor air system handles heating, cooling, dehumidification, and ventilation in one unit. DOAS unit delivers 100% conditioned outdoor air, pre-treated to the exact temperature and humidity your space requires. Your parallel HVAC system handles the rest.
We carry DOAS units from multiple US-based manufacturers in configurations from 3 to 100 tons, with airflow from 500 to 22,000 CFM. Every unit ships with the manufacturer’s full warranty. Our engineers match the unit to your application, not a catalog.
Have questions? Contact an engineer
DOAS vs. RTU and Make-Up Air
Three systems handle outdoor air in commercial and industrial buildings. Each takes a different approach to ventilation, temperature, and humidity.
| System | Outdoor Air | Heating | Cooling | Humidity Control | Typical Limitation |
|---|---|---|---|---|---|
| RTU | 5-30% mixed with return air | Yes | Yes | Limited | Not built for high outdoor air volumes |
| Make-Up Air Unit | Up to 100% | Yes | Varies | None or limited | Typically heats or cools, not both |
| DOAS | 100% | Yes | Yes | Full (latent + sensible) | Handles ventilation load only, not space conditioning |
A DOAS unit pre-conditions all outdoor air before it reaches your occupied space. Your parallel system (chilled beams, VRF, fan coils) handles temperature. The DOAS handles humidity and fresh air. That split eliminates the problems that come from forcing one system to do both jobs.
Available Configurations
DOAS units ship in a range of heating, cooling, and control configurations. The table below covers what you can spec.
| Component | Available Options |
|---|---|
| Capacity | 3 to 100 tons, 500 to 22,000 CFM |
| Heating | Gas-fired (natural gas or propane), electric, hot water coil, steam coil, heat pump |
| Cooling | Split DX, chilled water, air-source heat pump, water-source heat pump |
| Condensers | Air-cooled, water-cooled, water-source heat pump |
| Dehumidification | On/off or modulating hot gas reheat |
| Energy Recovery | Total enthalpy wheel (up to 80% efficiency) |
| Filtration | MERV 8 through MERV 14, metal mesh |
| Controls | BMS integration, standalone digital, analog, occupancy-based scheduling |
| Airflow | 100% outdoor air or partial recirculation via modulating dampers |
| Cabinet | 2″ double-wall, R-13 injected foam, galvanized steel with two-coat exterior finish (1,000+ hours salt spray rated) |
| Mounting | Rooftop, slab-on-grade, indoor mechanical room, horizontal duct |
The enthalpy wheel transfers heat and moisture between incoming and outgoing air streams. At up to 80% recovery, it reduces the load your compressors and burners handle. Variable-speed compressors match output to demand in real time and eliminate hard starts that shorten equipment life.
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.
Manufacturers
We are official representatives of the DOAS manufacturers listed below. Click the link to learn more about the manufacturers’ warranties and other information.
DOAS for Commercial Kitchens
Commercial kitchens exhaust large volumes of air through hood systems. A traditional setup requires two separate units on the roof to handle it.
| Traditional Setup | DOAS Setup |
|---|---|
| RTU handles dining room temperature | One unit handles the entire space |
| Separate MUA replaces air pulled by hoods | Replaces exhausted air and conditions it |
| Neither unit controls humidity | Full temperature and humidity control |
| Two roof curbs, two sets of maintenance | Single curb, single unit |
| Moisture enters the space uncontrolled | Moisture removed before air enters the space |
Food service spaces that benefit most from DOAS include:
- Food halls and open-concept kitchens
- High-occupancy dining rooms
- Ghost kitchen facilities
- Teaching kitchens
- Event venues and convenience stores
ASHRAE Standards 62.1 and 62.2 set minimum ventilation rates for these spaces. A properly sized DOAS meets those requirements in one system.
Get Your DOAS Spec’d
We represent multiple US-based DOAS unit manufacturers and carry units across the full range of configurations. Every unit ships with the manufacturer’s warranty.
Our engineers match the unit to your application. That means the right tonnage, the right airflow, and the right humidity control for your building and exhaust requirements. Need preliminary sizing numbers first?
Use our DOAS ventilation load calculator to get ventilation CFM, cooling tonnage, and heating MBH before you call.
Have questions? Contact us
