Hi, I'm trying to find Q for chimney/stove that looks very similar to the picture attached. I was going to use the formula below, but I realized that it does not account for the venturi effect if a chimney was conical in shape - i.e. smaller at the top vs. the base. Nor does it account for differences in the sizes of the air inlet and outlet. Q=CA(sq root(2gH(Ti-To)/Ti)) http://en.wikipedia.org/wiki/Flue_gas_stack where: Q = flue-gas flow-rate, m³/s A = cross-sectional area of chimney, m² (assuming it has a constant cross-section) C = discharge coefficient (usually taken to be 0.65–0.70) g = gravitational acceleration at sea level, 9.807 m/s² H = height of chimney, m Ti = absolute average temperature of the flue gas in the stack, K To = absolute outside air temperature, K I would like to know if there is a formula to find Q that would allow me to account for the following variables: - area of the bottom air inlet - area of the top outlet - temp inside the chimney - temp outside the chimney - height of the chimney Thanks in advance!!