Abstract: A pump for a spa or swimming pool adapted to heat the liquid being pumped includes a rigid plastic housing fabricated from (1) a first housing part having a volute portion defining a suction chamber enclosing a pump impeller and having an outlet therefrom and a boss defining an inlet thereto and (2) a second housing part having a discharge outlet and a tubular inlet. A sleeve extends between the tubular inlet and volute portion boss to define a suction inlet to the suction chamber. A body extension inserted between the first and second housing parts defines a pressure chamber surrounding the suction inlet and suction chamber and in communication with the suction chamber outlet and discharge outlet. An electrical heater is positioned in the pressure chamber to heat the liquid pumped by the impeller and is controlled by temperature and pressure sensing devices positioned in the pressure chamber.