by Ken Rajesky
Over the many years in Technical Service during the early Fall, we would receive calls from customers complaining of awakening in the middle of the night to a smoke alarm, and finding a smoke filled room where their stove was located. Obviously this was disconcerting and prompted a call to see what was wrong with their stove. We would first ask how cold was it outside during the night and how they loaded and set the stove for nighttime operation. Almost 99% of the time, the answer came back that it was in the high forties, early fifties (Fahrenheit). These temperatures would make the house uncomfortable if some type of heat was not utilized so it made sense that the woodstove was used. The problem that caused the smoke to fill the room and/or house was not a mechanical failure or design defect but instead, a lack of draft. The stove was improperly operated for the season.
What do I mean by that?
First, you need to understand draft, and how it works, so here is a quick Draft 101 course. First of all, draft is not shipped with stoves. If you don't have draft, you don’t have a chance, even with the best of products. Draft will vary from house to house on the very same block because of the many factors involved even though the homes may have been built identically. Draft evacuates by-products of combustion (smoke / gases) by a pulling or sucking action. This action pulls air into the stove for combustion purposes, and at the same time, pulls gases out of the stove through the chimney connector (stovepipe) and flue (chimney).
Draft is determined by contrasts——-the temperature of the air outside of the flue, versus the temperature inside the flue. The greater the temperature contrast is, the stronger the draft. Chimney height, flue size, chimney connector configuration, fuel, and altitude are also important factors, but temperature contrast is a greater factor. That’s why stoves typically operate wonderfully in the winter, and seemingly not so great during the other seasons. In the winter, the outside temperatures are colder, thus creating a greater contrast with flue temperatures. In the spring and fall seasons, the temperatures are warmer so the contrast isn’t as large. As one might say, when the contrast ain’t great, problems precipitate! So, if the outside temperatures on a cool October night are not near freezing, what can you do to ensure a good draft? First, remember the basics of draft—-contrasts. Next, remember that if its not real cold outside, you will somehow need to create that contrast by sending more heat up the flue than normal. You may even have to keep the bypass damper (if your stove has one) open for an extended period of time. This means sacrificing some efficiency but its a trade off that you must make. If its unacceptable, then turn on your furnace.
Accept the fact that you will probably need to build each fire from scratch so prepare yourself by collecting a lot of kindling & paper to make this easier. Then, begin to develop a good bed of coals (1-2” deep) before loading your larger pieces. Load just two pieces at a time. The idea here is to heat everything—-the stove, the flue, the house, and then let the fire die out overnight. Heat your home so its comfortable, but do not fully load the stove and set the air supply lever in the same manner as you would in January. If you do so, you will certainly lengthen your burn time. But, you will rob the flue of the crucial heat it needs to keep the temperature contrast high in order to sustain a good draft. If you insist on operating the stove in this way, the result will be the flue will cool, temperature contrast shrinks, draft slows down, and exhausts are not pulled out of the stove and house. The new result is a smoke filled room, smoke alarms blaring, kids crying, lost sleep, and anxiety. Who needs this when all you want to do is to stay warm and save money by heating with wood? But, if you can understand the basic concept of draft, and how to run the stove differently for the different seasons, thats 90% of the battle. Because of the many variables, you need to be flexible with your stove operation.
The Simple Solution Summary - Burn the stove with less wood and more air - do not smolder! In recognizing this, you will be successful, and sleep better.
(article submitted by Ken Rajesky)