Environmental Control of Gas Appliances: A Three Step Method for Detecting Unacceptable Flue Gas Leakage from Furnace Heat Exchangers

摘要

A three-step method for detecting unacceptable leakage of flue gases through furnace heat exchangers was developed and field tested. The first step of the method is a thorough visual examination of the heat exchanger with a strong light and a mirror. Next a check of the burner flames is made with and without the circulating air blower operating. The final step is to trace the migration of a 14.3 percent methane in nitrogen mixture from the combustion chamber to the circulating air side of the heat exchanger if a leak is present. A portable combustible gas detector is used which can be calibrated to respond to a leakage rate equivalent to 200 ppm carbon monoxide. The method was field tested by seven utility companies which compared the new three-step method to their normally used method. The majority of the utilities felt the new method was more reliable and accurate than their currently used method.