I use an oil filled radiator with a ceiling fan moving the air. I have a backup oscillating heater for when the oil filled cannot keep up. I have to make sure the oscillating on is blowing away from the racks otherwise some racks get hotter than others. Your area is smaller than mine which may make the issue larger. Buy a couple digital thermometers and place them in tubs at the extremes of the room (all four corners) and do some test runs without animals. It is my guess with a room of that size you might be better off with a radiator if you can keep it far enough away from the tubs. The radiator seems to use less power also. Make sure your thermostat can handle the pull of the heater. It is my belief that the radiators are more reliable also.