We installed a Lennox 100,000 btu 2 stage high efficiency gas furnace in our home about three years ago. When the furnace is exhausting outdoors we are able to detect the an odor that is very similar to chlorine. We have had the furnace checked for co and natural gas problems, nothing wrong. Also had the furnace serviced. I am an ex-smoker so the odor is not that strong for me. However, my wife is able to detect the odor when outdoors and the furnace is on. Does anyone know what the problem might be?