My furnace has a dedicated fan switch is this normal?

Hello I recently purchased my first house and fall is not upon us. While the furnace was checked by the inspector to see if it worked it was not noted that something was odd.

I have gone to use it this past week and here is what I found.



As you can see I have a power switch and a fan switch. This stuck me as odd because I either have to leave the fan running 24/7 or come in and turn it on and off every time I want the heat.

I looked at my thermostat



and found it only had 2 wires



The furnace is a Lennox 180DF.

Fuel Type: Gas

House style: single story 109 year old Craftsman i believe

And the thermostat is a Honeywell RTH7400

I have tested to see if the thermostat can control the fan at all and it can not. I tried leaving the fan off but the furnace on and see if it auto started. The furnace kicks on and I hear what sounds like it might be a fan but it is not the main one.

I do not know much about furnaces and have not been able to figure out is this is a normal situation or not.

I would like to know what I should do.

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