I bought a heat belt a week ago and it works great. It raised the temperature of the must from 60 to 70 degrees. I don't understand why it cannot be left plugged in for more than 8 days. Does anyone knows why? The secondary fermentation will take about 3 weeks according to the kit. And I will need to use it for that long since my basement is to cold (will probably get to 54 or so all of January and February).