Abstract: The float valve assembly is mounted in a liquid drain trap housing having an upper centrally located orifice and a lower centrally located outlet orifice and includes a float, an upper pin fixed to the top of the float and received in the upper orifice, a lower pin fixed to the bottom of the float in axial alignment with the upper pin and received in the lower orifice, a conical or semispherical valve seat at the lower end of the lower pin, and a mating valve seat-forming O ring clamped in the lower orifice. The upper and lower orifices are in axial alignment and form an alignment configuration for the float valve assembly by receiving therein the upper and lower pins and maintain them in generally vertical alignment. This ensures proper vertical seating and unseating of the conical or spherical valve seat on the O ring valve seat which is clamped within the lower orifice.