These units usually stand away from the wall and are very similar to a wood burning stove in appearance. Coaxial vent system of a pipe inside a pipe (generally 4 7) the inside pipe is for exhaust, while the outer pipe brings in outside air for combustion. The design of these fireplaces allow for a completely sealed system that does not compromise inside air quality of your home. It also lets you vent a product horizontally (great for when an appliance is installed on an outside wall). Direct vent appliances are usually limited to a length of 40ft (with a maximum horizontal length of 15ft) that will allow an appliance to function properly. The FDV451 Gas stove is a great way to add charm, romance and abundant warmth to a space. Expect the Kingsman tradition of excellence to continue as you enjoy high efficiency, low maintenance and performance.Depth: 19-11 16 Finish: Charcoal Glass: Single Ceramic Glass Viewing: 20W x 16-15 16H Height: 33-1 2 Ignition Type: Millivolt Natural Gas BTU: 23,750 to 34,500 Propane BTU: 24,500 to 31,000 Venting Size: 4 7 Venting Type: Direct Vent Width: 26{Features: Safety screen barrier included Millivolt valve system allows operation during a power failure with Hi-Low heat and flame adjustment Dual burner system, with Realistic Flame Pattern Heat radiating ceramic glass Mobile home approved - (Direct Vent Model Only) Approved for installation in a bedroom or bed sitting room {Fan Kit: Heat activated with variable speed control {Thermostat: Wall mount millivolt thermostat or programmable thermostat {Remote Control: Thermostat On Off modulating and fan control