My Quadrafire Castile pellet stove works great for a couple of hours but then shuts down and won't restart. It is hooked up to a digital thermostat which works well if the stove is only on for a short period. I am not sure if the stove is getting overheated and shutting down for as a safety feature or not. But the last couple of nights have been very cold and when I go to bed the stove is working great and when I wake up, the house is cold and the stove is out. Don't know what to do.