Question: I searched your database unsuccessfully for answers to the following questions. Can you answer or point me to a source for an answer for these questions. 1) Is there a method to calculate the output of a wood stove based on surface area and temperature.ie a wood stove with a surface area of 20 sq feet at 450 degrees is producing approximately ? BTU's per hour. 2) What are the highest,lowest and most efficient surface temperatures for an average wood stove. 3) What is the minimum flue gas temperature for a wood stove to minimize creosote formation. 4) Are those units which use a fan/heat exchanger system to extract heat from flue gases safe and efficient. Do they cause creosote buildup by reducing flue gas temperatures excessively. Answer: 1. There is a basic method for this, but I have not seen it for year. I'll dig around. Even then, more than surface temperature is at stake. Certain wavelengths of radiant heat can throw heat out from a hot part of a stove...while another model may have the same surface temp and not have this hot spot. 2. Most single wall surfaces on the top of a wood stove are best at 450 - 850 degrees. Cast-Iron and Soapstone stoves may be a 100 degrees lower or so. 3. Not really a question with an exact answer. If the wood is burned efficiently, then there is little creosote to form at any temperature. On the other hand, wood burned poorly may produce creosote at relatively high temperature. Best bet is to use a modern clean burning stove which has been tested to produce almost no creosote. 4. Flue pipe heat exchangers are really not suggested for the reason you mention.