Air-to-Air DOAS Heat Pumps

Air-to-Air DOAS Heat Pumps

Petra Air to Air Heat Pumps for Space Heating

Our heat pumps are customized for each job. Contact us for specifications and more information:


Air-to-Air DOAS Heat Pumps

To enhance indoor air quality (IAQ) to the highest extent, bringing in 100% outdoor filtered air to an indoor space is essential. That’s where Dedicated Outdoor Air Systems (DOAS) come in — ensuring that as much outdoor as possible is coming indoors.

On top of a DOAS system, to maximize system flexibility and operations, adding heat-pump capabilities is the answer. Thus, a DOAS heat pump is an excellent choice for improving IAQ, energy efficiency and cost savings.

Air-to-air DOAS heat pumps take energy from the outside air and transfer it to an airstream that will be delivered directly to a building for space conditioning. These systems work in all climates, including the cold weather of the New York City metro area.

Addison AK 1 DOAS Heat Pump
Petra PPH 100 Doas Heat Pump



Addison AK 1 Series Compact DOAS

As buildings and city centers continue to evolve, rooftop space comes more at a premium. At Addison, the drive to provide the best solutions for customers has lead to the continual improvement and expansion of their highly acclaimed AK Series.

The AK Series delivers exceptional performance and versatility over its now 3 – 90 Ton range. The all-new 1 Series cabinet features an even more compact footprint with new capacities and efficiencies. The CoilMatrix 4-coil system features a variable sensible/latent ratio for even more application versatility and flexibility. Additionally, the compact 1 Series footprint is a drop-in for many competitor footprints. From Retail, Offices, Hospitality and more, the AK Series is perfect fit for your next project.

Addison AK 1 DOAS Heat Pump
Standard and Optional Features
  • Capacity from 3 – 8 Tons
  • Airflow from 400 – 2,000 CFM
  • 2” Foam-Injected Double-Wall Construction (R-13)
  • Hinged, Double-Walled Access Doors
  • Industry exclusive Patented CoilMatrix 4-Coil System
  • Modulating Reheat Circuit
  • Fully Variable Speed Scroll Compressors
  • All-Digital Controls with BAS Integration
  • Direct Drive EC Plenum Supply Blowers
  • Modulating Electric or Gas Heat
  • 2,500 Hour Salt-Spray Rated Cabinet
  • MicroChannel Condenser Coils
  • Up to 6” of Media Filtration
  • Multiple Service Access Points
  • Reduced Cabinet Weight
  • Compact Footprint
  • Optional FrostShield TM Defrost Free Heat Pump Operation
  • Optional 10,000 Hour Corrosion Protection
Addison AK 1 DOAS Heat Pump
Addison FrostShield

FrostShield is a revolutionary new mechanical and unit control technology that not only extends the operating range of air-source heat pumps, but also removes the need for the unit to enter defrost mode during heating operation. This feature extends the life of HVAC equipment, has the potential to save a tremendous amount of electrical energy, and improves occupant comfort.

  • Normal operation: The air-source heat pump operates as it normally would when in heating mode sending fresh, clean air into the building.
  • FrostShield Detection: As conditions near frosting levels, FrostShield detects outdoor coil temperature levels and determines the precise amount of hot discharge gas needed to prevent frost from forming.
  • FrostShield Protection: FrostShield maintains the coil temperature above the threshold where moisture condenses and frost forms. This prevents the unit from switching to cooling mode, saving energy.
Addison FrostShield for Heat Pumps
Benefits of Addison FrostShield
  • Uninterrupted Comfort: FrostShield allows uninterrupted operation of energy-efficient electric air-source heat-pump heating to continuously deliver fresh, clean air.
  • Green Technology: FrostShield is the only air-source heat pump technology that can be applied to continuous heating of ventilation air without relying on supplemental heat from wasteful strip heaters or fossil fuel.
  • Energy Savings: Without having to switchover to defrost, enormous amounts of energy are saved by not having to utilize heat from the building to clear the outdoor coils.
  • Wider Range of Applications: FrostShield allows operation in the coldest climates where heat pumps are not traditionally applied without the need for a backup heat source, such as a furnace or electric heat.


Petra PPH – 100 DOAS Air Cooled

It’s becoming increasingly important to create a whole set of solutions for 100% Dedicated Outside Air Systems (DOAS), where all the features can be presented, furnished and controlled with optimum performance and quality in single piece unit. Petra Engineering Industries is providing a unique solution for quality and humidity control in addition to the vast choices of extra features.


  • Capacities ranging from 26 kW (7.5 TR) to 176 kW (50TR).
  • Distinguished by a small footprint and high efficiencies.
  • Petra’s 100% DOAS rooftop is provided with environmentally friendly R-410a and optional R-407c refrigerant.
  • Factory assembled and tested packaged units minimize field installation and commissioning costs.
  • All units have a built DDC Controller with capability. Any units can be monitored through an IP address and labeled from any place.
  • Controller is BACNET native. It can communicate with most BMS systems available.
Petra PPH 100 Doas Heat Pump
Standard Features
  • Double wall construction made from 22 gauge galvanized steel, with 50 mm (2 inch) thick (3pcf density) injected foam insulation minimizes heat loss for additional energy saving, and thermal resistance R=13 hr.ft. F/Btu.
  • Heavy duty galvanized steel C-channel base with full supporting cross members made of heavy gauge galvanized steel.
  • Weatherproof construction for the entire unit exterior/interior with applied polyester powder electrostatic paint, oven baked which ensures durability by complying with a5000 hour salt bath test in accordance to ASTM A117 and ASTM B1117.
  • Single Width Single Inlet (SWSI) plenum fans with VFD for air balance.
  • 25 mm (1 inch) spring isolator under fan.
  • Extended face area filters (Merv-8) and coils reduce system pressure drops and improve efficiency.
  • High efficiency scroll compressors feature excellent reduction in noise and vibration provide higher redundancy reduced maintenance costs and enhance integrated part load values (IPLV).
  • Dual independent refrigerant circuits include manual shut off valves on the suction, discharge and liquid lines, accessible sight glass, filter drier and solenoid valves and high and low refrigerant pressure protection switches.
  • 3-phase severe duty totally enclosed condenser fan motors with current sensing overload protection and permanently lubricated bearings support extended product life.
  • Condenser fans are of the axial type statically and dynamically balanced selected for optimum efficiency and for maximum sound power reduction. Fan blades are direct driven by external rotor motor type and protected by steel wire guard coated with electrostatic polyester powder coating oven baked.
  • Copper coils with aluminum fins pre-coated with corrosion protecting coating, polyurethane anticorrosion.
  • Stainless steel drain pan “double wall, double sloped.”
  • Stainless steel coil casing for all coils: DX, HGRC and condenser.
  • Modulating HGRC hot gas reheat coil for humidity control.
  • Single power entry.
  • Double-sloped roof cover with rain gutter for the whole unit.
Optional Features
  • Copper tubes, copper fins coil.
  • Coil corrosion protection including polyurethane pre-coating (for aluminum fins) and polyurethane post-coating (for aluminum and copper fins).
  • Sound reduction options including low rpm condenser fan and compressor jacket.
  • Availability of using heat pipe coil which increase the Energy Efficiency Ratio (EER) with same unit’s footprint.
  • Digital compressor for low ambient control.
  • Convertible supply air opening for both bottom and side supply air.
  • Gas heater and electric heater for heating application (winter heating).
  • SCR control for electric heater.
  • Modulating kit for gas heater.

Contact Us About Heat Pumps

We have all the heat pumps necessary for your commercial/industrial or multifamily job. Contact us for customization information and specifications.

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