I am trying to put a furnace in my garage but only the fan runs I don't want a thermostat as I will shut off when temp is comfy, but furnace has a thermostat at the top of the furnace but can't figure how to wire it
The thermostat on top of the furnace may be there to monitor the temperature inside the boiler. Can you show us a picture?
It is not good to set up a furnace to run using only a manual shutoff. You might forget and leave the room and then the furnace runs forever.
When cleaning anything including baby diapers, it is better to sweep off or scrape off as much solid and semisolid material as you can first. (1) Less cleaning fluid or detergent needs to be used, (2) Less of a mushy mess which in turn means that bleaches or disinfectants will be more effective.
The furnace will not operate until you make the circuit through the switch/T-Stat on top. Theres a reason for the T-Stat. Safety. And thats why it will not run until you find out how to wire a furnace.