Variable speed central heat and air conditioning systems now on the market have the potential to save energy since they can match their operating speed more closely to the heating or cooling demand on a structure. However, current installation practices necessitate installing a duct system large enough to handle the (often infrequent) maximum air output of this equipment. At the more typical lower speeds of operation, the heated or cooled air moves slower and stays longer in the duct system, leading to tremendous energy losses. This project will develop a parallel duct system with air control valves that can selectively modulate duct capacity. The parallel duct system will provide increased insulation and greater R values, further limiting BTU losses in the duct system. Phase1 will develop and test three alternative parallel duct systems with associated valve control. Emphasis will be placed on a duct-in-duct design, in which a smaller low speed duct is enclosed within a larger high speed duct. Preliminary testing and measurement of duct BTU losses and air performance in a controlled environment will then be conducted on each system.
Commercial Applications and Other Benefits as described by the awardee: The parallel duct system should encourage the use of energy saving variable speed equipment. Significant energy savings should be realized for the potential moderate additional cost of the parallel duct system
