Tips for Achieving a Safe Chimney System
When you are choosing a fireplace or wood stove to build or install in your home, that is also the time to think about ensuring that venting will operate properly. Even the most exquisite fireplace or decorative wood stove loses its appeal when you end up dealing with back-puffing, smoldering fires, excessive sooting, and other undesirable symptoms of poor design. It is possible to achieve a flawless chimney system; so why not get it right from the onset and get the maximum practical enjoyment out of your beautiful heating system?
A well-designed venting system encompasses a balanced process of air supply, combustion, and exhaust. The system is driven by the chimney, which simultaneously exhausts flue gases and pulls fresh combustion air into the fire. There are some basic principles of draft and flow which can lead to successful venting.
The first part of the draft and flow principle is that hot gases from fires rise. The gases rise more quickly and efficiently when there is a greater contrast between the temperature of the gases in the chimney and the air outside. The best way to address this principle is to have a chimney that is mostly enclosed within the house as opposed to being outside or on an outside wall. When it is cold outside and the chimney is exposed to the cold from top to bottom, what naturally occurs is that the chimney fills up with a column of cold air. A fire cannot draft properly until the cold is pushed out; and even when the fire is roaring, the flue won’t be as warm as it would be with an enclosed chimney that is protected from the elements.
A second part of draft and flow is that there needs to be a continuous fresh supply of air that flows up the chimney. Many homes today are built so tightly that negative air pressure is created, which means there is not enough air available that will move up the chimney. Large exhaust fans can create this problem along with exhaust-only ventilation systems. Our chimney professionals can help you determine how best to fix the problem of negative air pressure in your chimney.
Chimney height also contributes to proper drafting. It is best when a chimney is located as closely as possible to the highest part of the roof. Chimneys are supposed to be built in a way that conforms to the following:
- The chimney should be at least 3 feet higher than the roof on the chimney’s uphill side.
- The chimney should be at least 2 feet higher than any section of the roof within a 10-foot radius.
The chimney flue must also match the flue collar on the appliance it is connected to. Wood stoves are tested and designed for certain flue sizes that will achieve maximum combustion and draft. If the flue is too large, the flow is decreased. When combustion gases are slowed down, two additional unwanted results are an increased amount of creosote and increased moisture.
The following are more tips to achieve a flawless venting system:
- Keep the chimney straight and free of elbows, offsets, and obstructions; these features create flow resistance.
- Choose a wood stove or fireplace insert that is certified by the Environmental Protection Agency (EPA).
- Properly insulate a flue to help ensure that the air in the chimney can be warm enough to contribute to a healthy draft.
If you are preparing to install a wood stove or fireplace or if your venting system doesn’t work properly, give our chimney professionals a call. We can help you identify and solve any venting problems you may have.
Chimney Solutions, Inc.
1155 McFarland 400 Drive, Alpharetta GA 30004