The Quadra-Fire wood stoves incorporate secondary burn tubes, which are more efficient, burn cleaner and require less maintenance than stoves with catalytic converters. More than 50% of the heat from your wood stove comes from burning the smoke, and stoves with secondary burn tubes burn that smoke inside the firebox, instead of in your chimney. Generally, the Quadra-Fire wood stoves average fewer emissions versus the EPA standard of 6 grams per hour. They are very clean burning. And, over the life of a catalytic converter stove, you will need to replace the converter several times. This is quite a costly maintenance requirement. You will not need to replace the heat tubes on the Quadra-Fire stoves.