What Is Wrong With My Fire?
Draft Problems
It can be frustrating when you build a fire and the smoke pours out into your living room instead of up the chimney. The heart of chimney design is to keep the smoke from entering your home and leaving in a safe manner to the outside. Smoke inside the house can set off smoke detectors and breathing in smoke is detrimental to your health. If you can smell wood burning inside your home, it is an indication that you have a draft problem. It important to remedy drafts in the chimney, but what causes these drafts is not always an easy answer.
If your fire is hard to start or produces a lot of smoke, it may be time to have a certified sweep take a look.
If you have encountered draft problems in your chimney where smoke is entering your home, due to the variable nature of home and chimney design, an inspection will likely have to be done by a certified chimney professional to properly address any draft or down draft issues.
Chimney Design
Before understanding why down or back drafts occur, we must look at how chimneys work. The main principle behind the smoke going up the chimney is based upon hot air rising. As the hot air rises from the fire, it is gently pushed into the narrow opening into the flue. These angles and placements of design are critical for proper function. There is a delicate balance between heat and air pressures inside the home and the outside air pressure. Negative air pressure in the room (when air pressure in a room is lower than outside air pressure) prevents the smoke from leaving and causes the back draft and smoke enters the room instead of the chimney flue. Why this occurs can be a variety of factors including blockage, improper firebox design, improper flue design, structural damage, blockage, or other external factors.
Blockage
Blockage of the chimney can be anything from an improper functioning damper to animals that are stuck. The damper might also be too small for the opening needed. Animals can also leave nests behind inside or on top of your chimney that is creating a serious air obstruction. Creosote build-up is dangerous due to fire hazards, but there can be enough in the flue to cause this air pressure balance to sway the other direction. A proper and non-evasive inspection can reveal most of these blockage issues.
Improper Firebox and Chimney Design
In building a house, sometimes the look and design comes before function. An improper size firebox can easily throw off the ratio needed to pull smoke through the flue. The firebox must be in proper ratio of size to the chimney; a bigger firebox needs a taller chimney flue. Sometimes the chimney can be raised, or the firebox can be altered. Fire should also be at the very back of the firebox, and a firebox may be too shallow to function properly.
External Factors
Fire needs oxygen, pure and simple. A fire will pull the oxygen from a room quickly, and many modern day houses are tightly sealed and air pressure inside drops. It can drop so much so quickly, that the pressure inside is now lower than outside and a back draft is created. One remedy is opening a window in the house to equalize the pressure outside, but that defeats the purpose if you are trying to heat your home. An exhaust fan might be needed to properly vent the smoke out of your house and pull enough oxygen into the fire for the fire and chimney to work properly.
Tips
Here are some helpful tips to use in trying to prevent draft problems in your chimney
- Have your chimney inspected by professional on a regular basis to ensure proper function and address any key issues.
- Always burn properly dry seasoned firewood. Freshly cut wood is too moist and creates more smoke than fire.
- Avoid using other air vents in the same room while the fireplace is in operation.
- Always build the fire in the very back of the firebox to ensure proper smoke flow.
- Never use a fireplace that has continual draft problems. Wood smoke is dangerous to your health and toxic.
If still unable to remedy the draft problem yourself, consult a chimney professional.