I used Inkbird IPT-2CH V2.0 and ITC-308-WIFI to control heating mats and heating wire for gardening to keep some refrigerators and freezers from going below freezing. They are full of my late fall crop harvest of carrots, kale, turnips, beets, brussel sprouts, apples, etc . In the past I used bottles of hot water as needed but this year I am automating the process as much as possible.