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RETAC Product

High Efficiency Rooftop Units (RTUs)

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Condensing modulating rtu modulation gaspack gaspac packaged doas make-up air MAU MUA
Created 10/26/2017 by Christopher Kroeker
Updated 4/12/2019 by Mark Rehley
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Packaged, weatherized, commercial natural gas indirect air heating systems that may or may not include ventilation and/or air conditioning, mounted externally to a building, that capture heat from the products of combustion (flue gases) to achieve a minimum thermal efficiency (TE) or annual fuel utilization efficiency (AFUE) of 90%. Also includes non-condensing products that use modulating gas valves. 

Contributing Org
NEEA (Jeff Rigotti)
Market/Commercial Readiness
Level 4
Growing (commercially available in NW from at least 2 mfrs, growing market demand)
Product Performance
Level 3
Lab Validation (independent lab testing of features and savings)
Program Readiness
Level 4
Full-scale Pilots (performance at min. of 4, formal market study underway, well developed risk assessment)
Energy System(s)
Energy Subsystem(s)
Rooftop Units and Air Handling Units
Building Type(s)
Commercial:Food Service
Commercial:Residential Care
Cost and Savings
Unit Cost: N/A
Savings Type: GasSavingsOnly
Elec. Unit Savings: N/A
Gas Unit Savings: N/A
Unit: N/A
Benefits and Regional Potential
Non-Energy Benefits: N/A
Elec. Potential: N/A
Gas Potential: N/A
Explanation: N/A
EE or DR Benefit
Energy Efficiency Benefit
RTF Research Plan
RTF Sunset Date
Additional Information

Products include:

  • Dedicated outdoor air system (DOAS*) units
  • Makeup air system units (MUAS**) units
  • Gas packs***
  • Capturing heat from the products of combustion causes the water vapor component to condense, and since the units are typically mounted on building rooftops, the units are referred to as condensing rooftop units, or condensing RTUs. The baseline units that condensing RTUs replace are referred to as non-condensing, or standard RTUs, and have TE/AFUE ratings of 80-81%.


Heating Module Specifications


≈80% TE products which use modulating gas valves and have stainless steel secondary heat exchangers



93% Thermal Efficiency (TE), 400 MBH input retrofitted to select 12.5 - 25 ton Voyager Light Commercial RTUs (furnace supplied by Beckett and Heatco)

Note: very limited product offering


90% TE, 150 to 600 MBH input, 10:1 turndown, up to 9350 cfm (100% OA – DOAS product line supplied by others)

Engineered Air

90% TE, 100 – 1,400 MBH input, 15:1 turndown, 1,000 to 44,000 cfm


93%TE, up to 500 MBH input, 7:1 turndown, up to 12,000 cfm

Reznor (now part of Nortek Global HVAC)

93% TE, up to 600 MBH package (400MBH split), up to 10:1 turndown, from 500 to 11,500 cfm package (6000 cfm split).


95% AFUE, 39 to 96 MBH input, 2 stage, up to 1,895 cfm


93%TE, up to 800 MBH input, 10:1 turndown, up to 16,000 cfm

ICE Western

91%TE, 200-3000 MBH input, 60:1 turndown, up to 50,000 cfm


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