The introduction of variable refrigerant flow (VRF) expands the range of development potential for HVAC systems. The hybridization of traditional HVAC ducted systems and ductless VRF integrates both the advantages and disadvantages of each system type. Existing research does not focus on hybridization but on individual component evaluation that covers quantitatively expansive evaporator or multiple compressor configurations. The Trane Residential Heating and Cooling Research Lab at the University of Texas at Tyler was used as the research facility to experiment and validate a hybrid ducted-ductless HVAC system where a ducted attic air handler unit and three ductless evaporator units were installed. Spatial temperature and component operation were acquired through independent data acquisition systems to report daily data based on successful evaluation scenarios. Control of the system was assessed to be done very well given the zoning layout for the indoor units. Efforts to individualize zones for the ductless components had limitations since two indoor units shared an open floor plan. Temperature variation was found to be uniform with even one indoor unit and further balanced with addition of hybrid components with refrigerant line pressure and temperature response to compressor operation increase.

Date of publication

Summer 7-31-2019

Document Type




Persistent identifier


Committee members

Nelson Fumo, Tahsin Khajah, Mohammad Abu Rafe Biswas


Master of Science in Mechanical Engineering

Available for download on Friday, July 30, 2021