If the manual permits a clearance reduction using an NFPA211 design wall shield then the clearance can be reduced to 12". But remember that single wall stove pipe has a clearance of 18". If the stovepipe needs a clearance reduction too then it will need either wall or pipe shielding. Or switch to double-wall stovepipe which has a 6" clearance.I believe my fireplace has to be 18 inches from combustibles. But if I put some sheet metal on the wall 1 inch from the wall can I move my stove closer?