Yes in theory it may. Considering the fact that it is a closed space to begin with meaning your incubator, you dont need to close in the flexwatt. Covering flexwatt makes it heat up to hot. This is why you see people browning the bottom of tubs when using belky heat with tubs that sit on it. That fridge or cooler is already well insulated to begin with. The object of a fan in an incubator isnt to move the heat. Its simply just to circulate the air inside the incubator. By covering the flexwatt and making it heat up more you are basicalky creating a hot air blower. I will bet if you uncover the flexwatt and let the fan just move air without covering the fan up you will hold your temps perfect with a good thermostat.