GF1800 Natural Gas/LP Heater The Monitor GF1800 gas heater runs on either Natural Gas or Liquid Propane. This efficient supplemental heater can provide comfortable dependable heat to spaces up to 800 sq. ft. GF3800 Natural Gas/LP Heater The Monitor GF3800 gas heater runs on either Natural gas or Liquid Propane. This efficient supplemental heater can provide comfortable dependable heat to spaces up to 1500 sq. ft. 2200 Kerosene Heater The Monitor 2200 space heater runs on either k-1 Kerosene or Low Sulphur No.1 Oil. This supplemental heater is designed to keep up to 1,000 sq. ft. comfortable on between .07 - .164 gallons per hour, depending on the heat setting. 2400 Kerosene Heater The Monitor 2400 kerosene heater runs on either k-1 Kerosene or Low Sulphur No.1 Oil. This supplemental heater is designed to keep up to 2,000 sq. ft. comfortable on about 1.5 – 2.0 gallons a day. This direct vent supplemental heater offers a 15% energy savings. That means hundreds of dollars in savings each year.