Traditionally, ventilation and air conditioning ducts have been manufactured with rectangular cross sections. The rectangular duct can easily be adapted, e.g. to restricted ceiling voids and plant rooms, however, often at the cost of efficient airflow design and possible cost savings. A round duct system normally performs better and offers a more economical solution, which is the reason why it always pays to study and compare the ductwork design before selecting which type is to be used for a specific application.
The purpose of this project was to evaluate duct sealing as a means of reducing the energy consumption of hot air distribution systems in central Pennsylvania houses. Five houses were studied, all of which were heated with forced-air electric heat pump systems. During the winter of 1995, the heat pump energy consumption, supply air temperature, and the temperature at the thermostat were monitored continuously for approximately two months prior to the duct retrofit. A test also was performed to measure the leakiness of the ductwork.
Research over the past five years has indicated that a significant majority of the cost of residential retrofit duct sealing is in the labor required to find and seal those leaks. This paper describes the results of a field investigation of the performance and practicality of sealing residential duct leaks from the inside by means of a technique based upon injecting a fine aerosol spray into the duct system. The field results presented are from 4 7 houses located in Florida.
This report is one of a series giving practical advice on methods of reducing radon levels in existing dwellings. It is intended for the guidance of householders and builders who seek to reduce radon levels in dwellings by sealing cracks and other discontinuities in solid ground floors. The remedial measures described are mainly for concrete floors laid directly on the ground but some of the principles could be used with suspended concrete floors and, to a lesser extent, with floors consisting of large stone slabs.
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