I to have a old waterbed heating pad that was salvaged. It has lots of disclaimers on it to only use under a water mattress as a possible fire hazzard???? Only able to find some info on re-using it as a seed tray heater, but it seems to be able to be reto-fitted for carboys also?? It has a controller & a temp sensor prod, about 15 inches by 36 inches, rubber coated material. It was designed to warm water, so should also heat the carboys, I have some 3 inch styrofoam sheets that could make a box/tray to set it in. May try a test using a carboy with just water or a 5 gal plastic water jug to see if I can control the heat & temp in them. Don't want to chance loosing a full carboy of wine but this would be ideal if able to control the heat. Would be a great help in the colder months...
Any comments or suggestions are welcome......
Al