When we bought the house there was a free standing heater sitting there. Gas burner, and completely out of style with the rest of the place, and since the “hearth” was just a bunch bricks glued to the floor and wall, we had no qualms about tearing it out!
Any times you are installing a fuel burning appliance in your house, go to your insurance company and get their list of specs, their footing the bill if it burns down building codes mean F all. Had it out with more than one building inspector.