The ones that run from heat are stove top to move radiant heat. They don't move much unless you have no power available and need that type. Then it should be an expensive sterling type engine type to move enough from a freestanding stove. You're extracting heat by convection;
You don't have a regular stove top. The heat you're trying to extract is from around the vent pipe leading from firebox to the outer shell that makes an air space around the firebox. This is convected heat, compared to radiated heat. It pushes the heat convected to air out around the rear of the Insert that would only drift out naturally and also radiate through outer shell to heat the masonry hearth behind it, radiating outside and upward through the chimney mass and roof. The blower brings the heat inside also removing the heat from the hottest parts, around the exhaust vent. Look under the front of ash fender (shelf) for a slot all the way across Insert. That slot is designed to blow air under firebox, up the back, and out the top slot, forward. There are optional ways to connect blowers if you have slots in the front face cover as well. It should move 225 CFM. They all push air out the top slotted vent where there should be an angled deflector to prevent rising heat from mantle.
A good thread showing blower types as well as homemade;
made-a-blower-for-my-fisher-insert.117672