Ensure your stove is operating at the correct temperature by using this magnetic thermometer that attaches to your stove/pipe. If your stove is too cold then creosote deposits will form, if its too hot then you are wasting energy.
Our fluesystems.com stove thermometer attaches magnetically, directly to metal flue pipe. Optimal location is at eye level, no less than 300mm (12") above the top of the stove, where you can easily see it in the room.
For most woodstoves, ideal operating efficiency is between 400°F and 650 °F (200°C-350°C), the middle zone indicated by the pointer.