If these generate a considerable amount of heat, I might even use it to warm my little sisters hermit crab tank, and heaters like that use around the same amount of power.
Most heat generated in electric appliances, electronics and computer gear is caused by inefficient use of electricity. For example a 100 Watt bulb is drawing 100 watts, but not all 100 watts is going into the creation of light, a lot of it is wasted in heat, and that's why the bulbs get so hot.
I'm guessing the ASIC's must be pretty efficient, but even if you look at the worst case of 100% heat loss, you're only look at a 4.5 watt or 60 watt heater. I'd be shocked if even the SC puts off more heat than a single GPU, and even then, that's a stretch.
Either way I don't need that much heat! Although I forget that it wont give off 100% heat, haha