A wood pellet stove operable to mount to a wall includes a combustion chamber, a combustion chamber door, and a hopper. The combustion chamber has a front, back, and side. The combustion chamber door is in the front of the combustion chamber. The hopper is mounted at the side of the combustion chamber. The bottom of the hopper is below a top of the combustion chamber, and a top of the hopper is substantially coplanar with the top of the combustion chamber. The stove may also include a sight glass or fuel level monitoring system for determining a fuel level of the hopper without opening the hopper.