Infrared energy is radiated outward from the fire. This energy is converted to heat on the surface it strikes, such as skin, the surface of a chair or your clothes. But if something comes between you and the fire, you notice the difference. The temperature of the air has not gone up one degree, and chances are it has dropped because air needed to supply the fire comes from outside at much cooler temperatures. A wood stove, accompanied by a glass enclosure on the fireplace, is the best way to heat with wood. The average volume of air that is pulled through an open chimney in an hour is equal to twice the total volume of air in your house. This varies slightly depending on the chimney and the size of the house but not by much. So all night while your furnace is busy pumping hot air in, the chimney very efficiently pumps the hot air out. This is why glass enclosures are important in helping to stop heat loss.
There are five good reasons to have a chimney cap:
A build-up of creosote in a chimney is a potential fire hazard. Dust-like carbon deposits called creosote collect on the inside of a chimney flue, impairing the draft. Creosote is a natural by-product of burning wood. The build-up will vary depending on the type of wood most used in the fireplace. Soft woods, including pine and artificial logs, produce the highest level of creosote. These burn fast and leave a high deposit of creosote. Juniper is a little better. The best woods to use are hard woods, which include cedar, oak and mesquite. These burn slower, hotter and leave fewer deposits of creosote. Creosote burns with an intense flame that can damage mortar. In a matter of seconds the fire spreads up through the flue, as the creosote is burning, creating a draft that only helps the fire burn. This is a chimney fire; it sounds like a roar, like a rocket taking off in your living room.If you think you have a chimney fire, leave the house and call 9-1-1. The National Fire Protection Association recommends that chimneys be inspected once a year and cleaned if needed. When used regularly, the chimney should be checked every six months. How do you know whether your chimney needs cleaning? You may be able to tell by using a powerful light and a mirror to look up the flue from the bottom. If the bricks look pink, you're okay. If they are black or furry looking, it's time for cleaning.