Dave is definitely right. Something else to remember about the heating elements is size. The wattage is driven by the surface area of the element; a small element (like in the #1) needs much less wattage to heat the space in a model 1. The 700 watt element in a 2 is due to the length of the element (about 3" longer). The 3 is even bigger yet. Putting a larger element in a unit that doesn't need one could be overkill, at best, or disastrous at worst. If the element heats way too fast for the enclosure, it will likely be hard to control.