I have a two 1/2 year old Trane XE 90 natural gas forced air furnace located in the basement next to laundry room. Recently, my wife noticed a persistant gas smell and called the installer. During several visits they IDed several minute leaks at the piping connections and fixed them. There remains, however, a faint gas smell which remains for a few minutes at the end of each heating cycle and then dissipates. It accumulates at the top of the stairwell adjacent to the laundry room. If you stand close to the furnace, you can smell a faint odor of gas most of the time. My installer says that there is nothing more that can be done and that this is normal. Is there anything else we should be doing? Thank you.