After reading several posts on other subject I realized that draft inducer may not need to be on all the time. I just want confirmation that it is normal or not. Since I moved to the house the furnace was working the same way for 10 years. As I am typing now furnace is working and inducer wheel is spinning creating lots of noise. If this is not normal please let me know what is wrong with it. Thank you.

Depending on the AFUE, it may run all the time while in the heat cycle. If it is noisy, check for debris on the blades that would throw it off balance and see if there is an oil port on the motor. If it appears loose-wiggle it back and forth-you may need a new motor. Don't know the cost for your model but typically easy to do.