ARLINGTON, Va. - The Air Conditioning Contractors of America (ACCA) has released the first two in a series of new technical reference bulletins on its Web site. According to the association, ACCA Technical Bulletins will be released on a monthly basis and are designed to present basic concepts in a contractor-friendly format or respond to problems and queries from the field.

The "Comfortable and Healthy Homes by Design" bulletin has been developed to help contractors evaluate the performance of existing or proposed comfort conditioning systems. It brings factors such as temperature, humidity, and indoor air quality in balance with the metabolic activity and respiratory requirements of the occupants of a home.

"Basic Principles - Residential Duct Sizing Calculations" introduces the basic principles that are associated with sizing duct runs, so that proper air-side design can be achieved. The objective of the procedure is to size the duct system so that it will work with the blower that is supplied with the HVAC equipment. The identified procedure produces a design that provides the correct airflow to each outlet and from each return.