Rinnai Infinity FFWALLTERM horizontal flue terminal There are 4 flueing options that enable the installation of an internal continuous flow model. Vertical Direct Flueing straight up through the ceiling and penetrating the roofline. Horizontal Direct Flueing 90DEG bend off top of unit, backwards or side wards through the wall Horizontal Extended Flueing identical to horizontal flueing but with additional components to extend the length of the flue Combination Flueing mixture of both horizontal and vertical flues