natural gas

[tomd7735]

If you are referring to a high efficiency furnace, the flue is a 2-2 1/2" plastic pipe. The smell of gas there indicates incomplete combustion. This would cause a higher bill. It would be best to call for service. It may need cleaning of the secondary heat exchanger; especially if the filter doesn't get changed often. Or there could be a problem with the combustion air blower...
Tom D. HVAC Mech. 

[nikkilucy]

natural gas Furnace 2 yrs old. i can smell gas outside at the vent when it is running. is this normal?