Preheating the Flue is Key to Preventing Creosote Accumulation
A fast hot fire will preheat the flue and reduce the chance that creosote will accumulate. This preheating will also set the flue up to “draw” properly. Once airflow has been established in the flue, the intake ports on the stove will allow sufficient air to enter and to burn more completely. The key to low creosote build up is to have the chimney temperatures well above boiling to keep the wood’s moisture in the gas phase before it leaves the pipe. If the pipe is cold, these unburned gases, moisture and carbon products can condense on the inside of your flue.
Smoke and Coals
When a fire is first started it will smoke. These are the combustion gases that have not yet reached combustion temperatures. Sometimes you can watch this smoke “burst” into flames when it has become hot enough. On winter evenings, looking over my town, you can often see various plumes of smoke as people get their evening fires started. Once the fire is well established, there should be very little, if any, smoke. If your fire is still smoking by the time your kindling has been used up, your firewood may be too wet, or your air supply too low. When starting a fire in a wood stove, it is best to fully open all vents or even leave the door ajar to allow the fire to burn with the most robust exposure to oxygen.
Timing Your Fire Right
In my big stove, the start up takes about 15 minutes. We like to start with smaller bits of wood for the startup and then toss in the larger pieces. After about 30 minutes, a coal bed starts to form and we close down the catalytic vent and set the intakes to about 50 percent. Once the stove is in this state we can add large pieces every couple of hours. On really cold nights, or when the winds are cranking, we load up extra logs before bed. In the morning we can often resurrect a few coals and start all over again. Maintaining a shallow ash bed (about 2″) actually allows for better fires. We clear out the ash after a few weeks worth of fires. If your stove is running clean, the hot ash buildup should be minimal.
Remember to always place ashes in metal ash buckets, never in paper bags. Once or twice each year we read in the paper about some home fire due to improper ash storage.