Purpose of furnace fan

[Rick Vollmer]

I have a gas furnace which has a fan that runs auto every two hours. I notice no air movement at all. Should there be some sort of air circulation or if not what is the purpose of the fan running?

Thanks in advance....

[Ralph Brady]

An induced draft furnace has two fans/blowers. One for the combustion gasses in the flue and the other, larger one to circulate the air in the house.
I know of no reason that either one should come one every two hours, or any other time that the furnace is not running.

Some thermostats do have an option to turn on the large circulation blower only, which I personally use to filter the air and improve ventilation in my house. This is typically controlled with a separate switch on the thermostat.

[C. Scott Justason]

If you have no airflow, and it's not the combustion motor running, you need to check that the squirrel cage is spinning. Could be a motor/shaft problem, or a belt if it has one.