The purpose of this project was to test a method of integrating solar heating with a small commercial air handling unit (AHU). In order to accomplish this a heat exchanger was placed in the reheat position of the AHU and piped to the solar heating system. This heat exchanger is used to supplement or replace the existing electric reheat. This method was chosen for its ability to utilize solar energy on a more year round basis when compared to a traditional heating system. It allows solar heating to be used for direct heating during winter and for reheating in hot humid summer weather.

Data was taken for seven days without the solar reheat coil (SRC) in place and for eleven days with the SRC in place. For this project two similar days (one with the SRC and one without) were compared and contrasted to determine the feasibility of a solar reheat system. The results have shown that the SRC reduced the electric consumption in the electric reheat coil. There were two main indicators of the energy reduction. First, energy consumption of the electric heater relative to the total energy consumed fell from 33% to 16% with the use of the SRC over a 12-hour period. Secondly, on September 5, 2009 the solar reheat coil saved almost 10 kWh, over 25% of the heater energy required for 24 hour operation.

This project has resulted in a working prototype for solar powered reheat. With a few modifications this system will prove useful in future research. With solar assisted reheat being one of only a few acceptable forms of reheat for ASHRAE 90.1 (2007), interest in this topic will continue to grow and further research will be necessary. Therefore, this project has put Purdue University and the Applied Energy Laboratory (AEL) in a position to be a frontrunner in the up and coming field of solar assisted reheat research.


Solar, Reheat, Heating, HVAC, AHU

Date of this Version



Mechanical Engineering Technology

Department Head

Vahid Motevalli, Ph.D, P.E.

Month of Graduation


Year of Graduation



Masters of Science

Head of Graduate Program

Gary Bertoline

Advisor 1 or Chair of Committee

William Hutzel

Committee Member 1

Daphene Koch Ph.D.

Committee Member 2

Rodney Handy Ph.D.