Abstract: The disclosed apparatus is disposed in the "U"-section deflector at the bottom end of flues connected to each other in a multiple-flue, vertical flue furnace. A deflecting plate and two associated projections, one on the plate and the other on the wall, influence the flow of gases in such a manner that first the radius of curvature of the gas making the turn is decreased, and second the distribution of flow at the input cross-section of the flow-receiving flue is more uniform. The first effect improves the effectiveness of fly ash removal from the turning gas stream. The second effect prevents localized sooting and uneven heating of a heat exchanger which may be installed in the end of the receiving flue.