On a recent inspection in Highlands Ranch Colorado, I was impressed with this furnace. The home is 10 years old, and this was the original unit. As you can see in the photos, it was recently serviced in October of 2012. The unit is immaculate, and the burners work correctly as the flames are bright blue with little yellow color in the flame. This indicates that there is the appropriate gas/ air mixture during operation. It is clear that this owner has kept up yearly maintenance and the technician involved has done quality work. Its important to check the furnace unit for regular service and to check it during operation whenever possible.