Question: I CURRENTLY HAVE DOUBLE WALLED STOVEPIPE ON MY WOODSTOVE. IWOULD LIKE TO INCREASE MY HEAT OUTPUT BY SWITCHING TO SINGLE WALLED PIPE.I REALIZE I WILL HAVE TO INSTALL A WALLSHEILD TO DO THIS. MY QUESTION IS HAVE THERE BEEN ANY STUDIES ON THE AMOUNT OF HEAT GAIN PER FOOT OF CONNECTER PIPE BETWEEN THE TWO DIFFERENT TYPES , BY THE WAY I HAVE FOUND YOUR WEBSITE VERY HELPFUL IN THE PAST. THANKS IF YOU HAVE ANY IMFORMATION FOR ME. Answer: As with most things, it depends. The heat gain is mostly found in the first 3-4 feet of pipe, after that it probably cools too much... BUT, it also depends on the stove model. Some put more heat up the chimney than others. In general, non-catalytic stoves put more heat up the chimney than cat stoves. I think it would be a fair guess to say that a 10-15% gain is possible in many circumstances.