To evaluate the energy-conserving potential of furnace retrofits, residential gas furnace field studies have been limited to either controlled-house tests or large cross-population surveys such as the Space Heating Efficiency Improvement Program (SHEIP) of the gas utility industry. This paper presents the results of a recent study in 150 low-income-family, detached residences in Illinois. The houses had been previously envelope-weatherized and the
furnace retrofit budget was limited to an installed cost not to exceed $300 per dwelling. The 150 total test sites were divided among three distinct climatic zones so that about 50 sites each were located in Waukegan (7000 annual heating degree-days), Carlinville (5200 annual heating degree-days), and Marion (3800 annual heating degree-days). The furnace actions undertaken included furnace tune-up, service or repair and, in few instances, furnace replacement (corroded or cracked heat exchanger). Each furnace was also retrofit by one more among four options such as Intermittent Ignition Device (IID), Thermal Vent Damper, either on the furnace (FVD) or water heater (WVD) vent connectors, or on both (TDD). The homes were monitored over a full heating season and pre/post gas consumption was established through gas utility customer bills for at least one post-envelop retrofit heating season and the post-furnace retrofit season (1985-86). Group-mean seasonal gas consumption reductions varied from -4.0 to 13.5%, at a 95% confidence level.

Units: I-P