Why the difference? High efficiency units have induced draft systems to force the flue gases to the outside and generally produce mostly water vapors. Now that you have some idea of what to look for, here are some guidelines for venting high efficiency units: A high efficiency flue should be at least one foot above the ground or 7 feet above a walkway, at least 4 feet below or beside a window, door or air inlet such as a clothes dryer, bath fan or range hood vent. The flues can be no closer than 3 feet to a gas meter regulator, which can occasionally release natural gas.
Call your agent and ask for a copy of the inspection report or a written explanation to better understand what needs to be done.
C. Dwight Barnett is a certified master inspector with the American Society of Home Inspectors. Write to him with home improvement questions at C. Dwight Barnett, Evansville Courier & Press, P.O. Box 268, Evansville, Ind. 47702 or e-mail him at firstname.lastname@example.org.