I use an oil filled radiator heater plugged into a Ranco thermostat set to 83 degrees. It ends up being on at least 12 hours a day during the winter as the house goes down to 63 while I'm at work. The built in thermostats on these have a reputation of being cheaply built and likely to fail. Whether it's actually true or it happened to one person and everyone just jumped on the blame wagon, I don't know. Better safe than sorry is the way I look at it.