Flue-Gas Condensate Disposal from High-Efficiency Gas Furnaces

摘要

This paper presents the results of a GRI project to identify and assess potential adverse effects associated with flue-gas condensate disposal in residential sanitary drain systems. The main thrusts of this project were (1) the on-line characterization of the flue-gas condensate and the sanitary system effluent from a typical home heated by a high-efficiency gas furnace operating in the condensing mode and (2) the investigation of corrosion of common plumbing materials in the effluent before and after condensate addition. In situ corrosion-coupon exposure tests of metals, mortar, and PVC plastic did not reveal accelerated corrosion or deterioration as a result of condensate addition to the drain system. An overall assessment showed that under normal living conditions it is expected that the condensate added to the residential sanitary drain will be diluted and neutralized by the sanitary system effluent which typically averages 30 to 60 gallons for each gallon of condensate generated. Under these conditions, condensate addition to the sanitary drain does not appear to increase the corrosion rate of common drain materials. The assessment further indicated that the addition of the condensate to the municipal sewage treatment system should not upset the sewage treatment system process, even under the conditions of 100 percent market penetration of condensing furnaces.