The energy crisis of October 1973 through the early spring of 1974 created an awareness of the need to improve the performance of gas-fired space heaters and conserve energy. Since then new spare heating equipment and retrofit items for installation on existing equipment have been offered along with claims of their energy-saving potential. The American Gas Association (AGA) Spare Heating Efficiency Improvement Program (SHEIP) was organized in the summer of 1976 to field test the energy saving potential of new space heating units and retrofit items installed on existing equipment. This paper will show how the test method developed in the SHEIP was utilized to conduct additional field tests and performance evaluations of vent dampers installed on gas-fired space heating equipment.