I think 1500 is the max but not sure if one with a larger surface actually puts out more heat or not. We like the Vornado which was top rated by Consumer Reports. The fan is always running to keep even heat but an adjustable thermostat varies the heat output. The air is warm and never hot to the touch. Expensive but comes in various models and styles. It heats our 30 foot MH down to possibly 30ish. Some big box stores or on line Once our switch broke so I sent it to the manufacturer and it's been good now for years.