The right chimney enhances the safety and performance of your high efficiency fireplace
Air cooled chimneys were designed for open wood burning fireplaces. Since open fireplaces produce very little heat, air cooled chimneys are not required to undergo severe chimney fire testing. These chimneys have no insulation; they stay cool by circulating cold air past the inner flue. As a result, the flue is colder than with an insulated chimney resulting in reduced draft and a greater chance of creosote formation. They are used on most entry level “builder box” fireplaces so they are usually constructed of the cheapest materials UL Standards allow.
Insulated chimneys were designed for wood stoves. Stoves can produce high flue gas temperatures and large amounts of creosote which can cause chimney fires. Stove chimneys are certified to much tougher safety standards which require the chimney system to withstand repeated 2100°F chimney fires. They utilize high temperature insulation and superior stainless steel making them much more expensive to build. They warm up quickly and are less likely to accumulate creosote.
To read the complete article go to http://www.icc-rsf.com/en/safety-and-performance