Abstract: A socket heat fusion apparatus is provided for simultaneously heating one end portion of a thermoplastic conduit and one end portion of a thermoplastic coupler so that the heated end portion of the thermoplastic conduit can be disposed in the heated end portion of the thermoplastic coupler to provide a substantially fluid-tight union therebetween. The apparatus comprises a body member having a first heat communication opening and a second heat communication opening, the second heat communication opening extending through the body member and openly communicating with the first heat communication opening; a first receptacle disposed on one side of the body member for receiving one end portion of the thermoplastic conduit, the first receptacle communicating with the second heat communication opening; and, a second receptacle disposed on a second side of the body member for receiving one end portion of a thermoplastic coupler, the second receptacle openly communicating with the second heat communication opening.