If it falls within your budget, Dyna-Glow’s 10,000-watt Electric Garage Heater offers unbeatable heat output. It emits 34,121 BTUs, which heats rooms as spacious as 1,000 square feet.

Costway 1500W Oil-Filled Radiator Heater Portable Electric Space Heater 3 Heat Settings $61.99 (was $179.99) BLACK+DECKER Portable Space Heater, 1500W Small Space Heater with Overheat Protection ...