A distribution tee assembly 10 for transferring the products of combustion from a heat exchanger 12 to an exhaust vent system 14. The distribution tee assembly 10 includes a distribution tee 16 having an inlet pipe 18 and two transverse outlet pipes 20, 22. A transition region 24 is located proximate a wall of the distribution tee 16. In the transition region there is positioned a deflector vane 28 which diverts incoming combustion products toward the transverse outlet pipes 20, 22. If one of the outlet pipes is capped, all of the combustion products are diverted to the unblocked transverse outlet pipe.