Lopi Endeavor and pipes installed along with OAK in 2009. Burn 24/7 thru the winter. Oak cut by me from logs, split and stacked, seasoned for 2-3 years. MC between 14 and 16%. Stove top 650 and pipe measured with Auber probe about the same. No secondary burn. Burning N-S, could never get the stove to burn E-W. Always left the back wood to smolder. Cleaned the stove and pipe end of last year. There was a thick coating of soot in the pipes. Used the soot eater to get to the top but I couldn't got my fiber brush past the offsets. First time that happened. Also I have noticed a light smoke condition tword the end of the burn. Average burn time 8 hours. Difficult to find someone willing to do a bore scope inspection of the stack.