Space heater and high efficiency are two phrases not usually found in the same sentence – except if you're talking about Rinnai's direct vent wall furnace.
About the size of a piece of carry-on luggage, this 11,000-BTU gas furnace packs enough punch to heat up to two average rooms.
Measured by the strictest real-use standards, the heater has an impressive 80 percent AFUE (Average Fuel Utilization Efficiency) rating.
Installation is fairly straightforward, requiring only a 3 inch hole for the outside vent and a 120 volt connection. The 7-stage modulating gas valve enables this compact unit to use the smallest amount of gas possible to provide heat. Available in natural gas or propane.