Development and field verification of a model of excess infiltration and house air infiltration for single-family residences

A comprehensive series of studies was conducted to quantify the factors affecting seasonal efficiency of space heating furnaces. Initial data were developed (in a laboratory model of a house) on how furnace cycling, wind speed, and structure looseness (or air charge rate) affect chimney flow by simulating a specific installation. A field study was also conducted in 20 test homes to verify the model, to extend its applicability to a wider spectrum of installations and residences, and to obtain additional practical data from the structures (e.g., crack lengths) in order to simplify the model for use by utilities, contractors, and furnace manufacturers. The results extended the applicability of the model to installations equipped with furnace retrofits (e.g., derates and vent restrictors). The results also indicated that the excess house infiltration, due to the existence and operation of a furnace, is variable and depends on the structure, installation, and climate.