Empire's Ultrasaver 90 is the most efficient space heater available on the market. Due to the high efficiency of this heater you can easily vent this unit with 1.5" PVC Pipe. Available in 35,000 and 17,500 btu units. Runs off propane or natural gas. Works at high altitudes. Built in control panel with 5 heat settings, built in thermostat, and modulating blower. The ultrasaver 90 can also be operated by remote control or any standard 24V wall thermostat. This unit requires electricity to operate. You will also need a condensate drain, condensate pump, or the optional condensate evaporator. The condensate evaporator will add humidity to the room by turning the condensate into water vapor. The Ultrasaver 90 is more efficient than any vented heater on the market including ducted central heating systems.