How much Sq feet will the World Marketing Kozy-World Infrared Variable Controlled 5 Plaque Vent-Free Gas Wall Heater unit heat?

Here are the manufacturers specifications... Fuel Type: LP Gas Controller Type: Variable BTU Rating: 25,000 BTU Width: 26.63" Height: 23-1/2" Depth: 8" Heating Area: 1000 sq ft