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Dedicated Outdoor Air System

RuppAir’s Dedicated Outdoor Air System (DOAS) is the ideal HVAC solution offering exceptional energy savings and unprecedented comfort and humidity control.

The DOAS is designed from its core to conserve energy and save on operating costs. Its rare earth magnet inverter scroll compressor eliminates excessive cycling, premature unit aging, inefficient hard starts, and unnecessary energy consumption. Modulating technologies allow it to deliver the highest efficiencies at part-load conditions.

The DOAS contains fully modulating refrigeration and optional hot gas reheat components that deliver the exact amount of air requested at the desired temperature and humidity. Variable speed components allow the unit to adjust its heating and cooling capacity to match the required load. This provides a consistent temperature throughout the space and avoids large temperature swings often associated with single stage equipment.

The DOAS achieves an impressive 20.2 IEER rating (Integrated Energy Efficiency Ratio) which is over 1.5x the ASHRAE 90.1-2016 IEER standard. Designed with the future in mind, it is poised to exceed rising IEER standards for years to come.

RuppAir offers unmatched factory service and technical support through its rapidly expanding nationwide service team. Each local service technician undergoes extensive in-house training to ensure your needs are quickly met and problems are thoroughly addressed. Since the DOAS is a fully standardized equipment line, service techs are able to stock most replacement parts on their trucks, eliminating long lead times often associated with service visits. Additionally, RuppAir’s DOAS is designed with service in mind, incorporating several convenience features to make support visits as smooth and efficient as possible.

CASLink, RuppAir’s proprietary cloud-based building management system, collects real-time performance data in order to verify proper equipment operation, recognize potential problems, diagnose minor issues, and analyze system efficiency. CASLink allows for remote unit adjustments, often eliminating the need for an onsite service tech visit. Every DOAS unit includes a CASLink system at no additional charge.

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Dedicated Outdoor Air System

  • Conserve Energy
  • Precise Control
  • Superior Efficency

DOAS is designed from its core to conserve energy and save on operating costs. DOAS’s rare earth magnet inverter scroll compressor eliminates excessive cycling, premature unit aging, inefficient hard starts, and unnecessary energy consumption. DOAS’s modulating technologies allow it to deliver the highest efficiencies at part-load conditions.

DOAS contains fully modulating refrigeration and optional hot gas reheat components that deliver the exact amount of air requested at the desired temperature and humidity. Variable speed components allow DOAS to adjust its heating and cooling capacity to match the required load. This provides a consistent temperature throughout the space and avoids large temperature swings often associated with single stage equipment.

DOAS achieves an impressive 20.2 IEER rating (Integrated Energy Efficiency Ratio) which is over 1.5x the ASHRAE 90.1-2016 IEER standard. Designed with the future in mind, DOAS is poised to exceed rising IEER standards for years to come.

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Features & Benefits

  • Mixed Air Temperature / Humidity Sensor
    • Monitors mixed air temperature / humidity
    • Available outdoor, return, mixed, discharge, and space air temperature / humidity measurements
  • Up to Three Layers of Outdoor Air Filtration
    • Standard 2" metal mesh outdoor air filters
    • Up to 4" additional filtration - MERV-8, 13, 15 & HEPA
  • Low-Leakage Outdoor Air Damper
    • Modulates to accurately meet variable outdoor air requirements
    • Integrated louver and bird screen assembly included
    • Exceeds AMCA Class 1A Leakage Standards
  • Wide Indoor Coil Design
    • Up to 7-row coil allows for optimal compressor efficiencies, full conditioning of outdoor air, and moisture control
    • Staggered coil design reduces supply air bypass
  • Electronic Expansion Valve
    • Provides automated superheat control and monitoring by modulating from 0-100%
    • Precise position control prevents liquid migration during off-duty cycles
  • Fully Modulating Hot Gas Reheat Coil (Optional)
    • Provides highly accurate humidity control
    • Electronic reheat valve allows for precise capacity control
  • Stainless Steel Sloped Condensate Drain Pan
    • Removable insulated drain pan allows for easy maintenance and serviceability
    • Float switch monitors water level and protects against condensate overflow
    • Exceeds ASHRAE 62.1 Standards
  • Modular Heating
    • Natural gas indirect fired furnace with constant 80% efficiency throughout modulation (90% high efficiency option available)
    • Propane, Heat Pump, and Electric Heat options available
  • Variable Speed Direct Drive Supply Fan
    • High efficiency Variable Frequency Drive (VFD) or Electronically Commutated Motor (ECM) options available
    • Low maintenance – no belts to adjust
  • Variable Speed Outdoor Fans with EC Motors
    • 10:1 turndown maintains peak efficiency for all outdoor air conditions
    • Aerodynamically designed bionic blades drastically reduce noise emissions
  • Double Wall, Galvanized Steel Construction
    • Insulated with 2” thick, foil-faced, R13 closed cell foam
    • G-90 galvanized steel
  • Removable Hinged Access Doors
    • Allow for easier maintenance and serviceability
  • Human Machine Interface (HMI)
    • User friendly interface allows for simple programming of temperature, humidity and scheduling settings
    • Access to real time temperature / humidity data and refrigerant temperature / pressure measurements
  • Integrated Controls
    • Multiple PID loops maximize energy efficiency
    • Several control offerings – full integration to BAS/DDC
    • Fully insulated controls cabinet reduces condensation, avoiding damage to controls
  • Danfoss Variable Speed Inverter Scroll Compressor
    • Modulates capacity to provide precise load matching with reduced energy consumption
    • Protective operating envelope minimizes risk of damage and premature failure
    • Variable frequency drive provides phase and over-amp protection to maximize life of unit
  • Mixed Air Temperature / Humidity Sensor

    • Monitors mixed air temperature / humidity
    • Available outdoor, return, mixed, discharge, and space air temperature / humidity measurements
  • Up to Three Layers of Outdoor Air Filtration

    • Standard 2" metal mesh outdoor air filters
    • Up to 4" additional filtration - MERV-8, 13, 15 & HEPA
  • Low-Leakage Outdoor Air Damper

    • Modulates to accurately meet variable outdoor air requirements
    • Integrated louver and bird screen assembly included
    • Exceeds AMCA Class 1A Leakage Standards
  • Wide Indoor Coil Design

    • Up to 7-row coil allows for optimal compressor efficiencies, full conditioning of outdoor air, and moisture control
    • Staggered coil design reduces supply air bypass
  • Electronic Expansion Valve

    • Provides automated superheat control and monitoring by modulating from 0-100%
    • Precise position control prevents liquid migration during off-duty cycles
  • Fully Modulating Hot Gas Reheat Coil (Optional)

    • Provides highly accurate humidity control
    • Electronic reheat valve allows for precise capacity control
  • Stainless Steel Sloped Condensate Drain Pan

    • Removable insulated drain pan allows for easy maintenance and serviceability
    • Float switch monitors water level and protects against condensate overflow
    • Exceeds ASHRAE 62.1 Standards
  • Modular Heating

    • Natural gas indirect fired furnace with constant 80% efficiency throughout modulation (90% high efficiency option available)
    • Propane, Heat Pump, and Electric Heat options available
  • Variable Speed Direct Drive Supply Fan

    • High efficiency Variable Frequency Drive (VFD) or Electronically Commutated Motor (ECM) options available
    • Low maintenance – no belts to adjust
  • Variable Speed Outdoor Fans with EC Motors

    • 10:1 turndown maintains peak efficiency for all outdoor air conditions
    • Aerodynamically designed bionic blades drastically reduce noise emissions
  • Double Wall, Galvanized Steel Construction

    • Insulated with 2” thick, foil-faced, R13 closed cell foam
    • G-90 galvanized steel
  • Removable Hinged Access Doors

    • Allow for easier maintenance and serviceability
  • Human Machine Interface (HMI)

    • User friendly interface allows for simple programming of temperature, humidity and scheduling settings
    • Access to real time temperature / humidity data and refrigerant temperature / pressure measurements
  • Integrated Controls

    • Multiple PID loops maximize energy efficiency
    • Several control offerings – full integration to BAS/DDC
    • Fully insulated controls cabinet reduces condensation, avoiding damage to controls
  • Danfoss Variable Speed Inverter Scroll Compressor

    • Modulates capacity to provide precise load matching with reduced energy consumption
    • Protective operating envelope minimizes risk of damage and premature failure
    • Variable frequency drive provides phase and over-amp protection to maximize life of unit

System Sizing & Specifications

Unit Size (Nominal Tonnage) 8 15 20 30
Min Airflow (CFM) 750 1500 2000 3000
Max Airflow (CFM) 3000 4500 6000 9000
Indoor Coil Rows 5 6 7 6
Cooling Turndown Ratio 7:1 4:1 4:1 4:1
IEER 20.2 18.8 18.2 17.8
Max Heating Turndown Ratio 15:1 9:1 9:1 10:1
Furnace Input Capacity (MBH) 50-200 150-500 150-500 200-600
Electric Coil Capacity (kW) 15-60 15-100 15-100 60-150
Curb Size (L x W) 75" x 49.5" 91" x 59.5" 91" x 59.5" 111" x 80"
Unit Dimensions (L x W x H) 81.75" x 80.75" x 60.75" 99" x 89.75" x 69" 99" x 89.75" x 69" 158" x 89.75" x 94"
Approximate Weight (lbs) 1650 2400 2570 4500

Case Study: Precise IAQ

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Case Study Application:

Commercial Testing Laboratory

Product Spotlight:

DOAS’s Modulating Capacity - Precise IAQ

A RuppAir Dedicated Outdoor Air System (DOAS) unit was commissioned this past February for a commercial laboratory in Maryland. The existing space conditions prior to the installation were poor, with overpowering Formaldehyde smell. The DOAS unit quickly and significantly improved the indoor air quality by bringing in 100% fresh outside air with precise conditioning.

Over 3 months of continuous operation since commissioning:

  • Maintained space temperature within the 68°F and 73°F set points 97% of the time
  • Space temperatures never exceeded +/- 2°F of the range
  • Cooling with reheat functionality maintained the space relative humidity below the desired 58% RH set point 97% of the time

DOAS’s operation has spanned February through early May. Traditional On/Off units have difficulty meeting the lower demands of this transition season due to excessive cycling. The DOAS’s modulating heating and cooling capabilities turn down to meet this “shoulder season” demand.

  • Combined heating and cooling runtimes of 38 and 13 days, respectively
  • Average compressor speed at 38% of full speed
  • Average compressor runtime of 70 minutes – cycling reduction protects the unit and extends its useful life

Conclusion:

RuppAir’s DOAS unit met the laboratory’s tight space conditioning demands while also delivering fresh outside air. The employees commented on the drastic difference in indoor air quality and the manager was very happy with the improvement.

Percent of Time at Space Condition Since Commissioning

Space Set Points:     Heating - 68°F  |  Cooling - 73°F

Space Conditions

38%

0%
100%

Average Compressor Speed

Compressor Speed Distribution

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Case Study: DOAS vs. RTU

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Case Study Application:

Commercial Dining HVAC

Product Spotlight:

A Tale of Two Franchisees – DOAS vs. RTU

RuppAir serves and monitors a restaurant chain with two franchisee locations in Kansas City. One of the locations, Site A, utilizes RuppAir Dedicated Outdoor Air Systems (DOAS) to handle the HVAC demands and the other location, Site B, utilizes traditional On/Off rooftop units (RTUs). The restaurants have nearly identical building design parameters and operation patterns. RuppAir analyzed the space condition and equipment usage data at each site to compare the off-peak performance during the transition (“shoulder”) season.

Data trends from March through May suggest DOAS as the superior solution:

  • More precise space temperatures show improved comfort
  • Lower overall utility costs
    • Despite fully conditioning the kitchen's make-up air
  • Proper runtime from superior controls and setback implementation
    • 32% reduction by eliminating excess overnight HVAC usage
  • Less equipment cycling from full modulation extends unit lifetime
    • 56% fewer cooling equipment cycles
    • 76% fewer heating equipment cycles
  • Reduced need to mix return air to condition outside air
    • Met the same conditioning demands with 57% less total air movement and significantly cut blower energy demands
    • Less total air allows for downsized, reduced-cost ductwork

Conclusion:

As demonstrated by the data gathered, traditional RTUs can experience difficulties handling off-peak times of the year. This may result in excessive unit cycling, reduced equipment lifetime, and uncomfortable variations in space conditions. Given that most locations spend the majority of the time in these offpeak weather conditions, the modulating capabilities of the DOAS unit offer a vastly superior solution.

Space Temperatures Ranges When Occupied

Average Equpiment Usage per Day

Average Equipment Cycles per Day

Location Customer
Volume
Natural Gas Electricity
Site A (DOAS) 42,425 $856.50 $6,059.46
Site B (RTU) 38,263 $1,633.33 $6,135.19
Comparison 11% Busier 48% Savings 1% Savings

Utility Comparison of Site A to Site B

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Features

  1. Danfoss variable speed inverter scroll compressor with VFD
  2. Mixed air temperature/humidity sensor measures outdoor, return, mixed, discharge and space air
  3. 2” metal mesh outdoor air filters
  4. Low leakage outdoor air damper, includes integrated louver and bird screen assembly, exceeds AMCA Class 1A leakage standards
  5. Wide staggered indoor coil design
  6. Electronic expansion valve modulates 0-100% providing automated superheat control and monitoring and preventing liquid migration
  7. Stainless steel sloped condensate drain pan, includes float switch and exceeds ASHRAE 62.1 standards
  8. Natural gas indirect fired furnace with constant 80% efficiency through modulation
  9. Variable speed direct drive supply fan
  10. Variable speed outdoor fans with EC motors, 10:1 turndown
  11. Double wall, G-90 galvanized steel insulated with 2” foil-faced R13 closed cell foam
  12. Removable hinged access doors
  13. User friendly human machine interface (HMI) for easy programming and data measurements
  14. Integrated controls with multiple PID loops to maximize energy efficiency
  15. Fully insulated controls cabinet
  16. CASLink cloud-based building management system

Options

  1. Up to 4” additional filtration – MERV-8, 13, 15, and HEPA
  2. Up to 7-row coil
  3. Fully modulating hot gas reheat coil; allows for precise humidity and capacity control
  4. 90% high efficiency modular heating
  5. Propane, heat pump, or electric heat modular heating
  6. VFD or ECM supply fans
  7. Fully integrated, BAS, or DDC controls

Certifications

The Dedicated Outdoor Air System is ETL-listed to the following standards: Standard for Safety Heating and Cooling Equipment ANSI/UL 1995, CSA 22.2 no. 236; American National Standard/CSA Standard for Gas Unit Heaters and Gas-Fired Duct Furnaces ANSI Z83.8-2013, CSA 2.6-2013.

The Dedicated Outdoor Air System has been tested in accordance with the following standards: ANSI/AHRI Standard 340/360 – 2007, ANSI/ASHRAE Standard ANSI/ASHRAE 37 2009.

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