Abstract: A spa heater/control includes sensors and processors to monitor and display indicia of common failures. The heater/control includes voltage sensors and processing to measure proper power connections to the heater/control.

Abstract: A vertically-oscillating spa massager for use in a hydrotherapy hot tub by a bather, and having a massager component slidably and captively mounted on a vertical track of a base member mounted on the hot tub. The massager component oscillates in a vertically reciprocating manner on the vertical track preferably by means of a rotating drive arm pivotally attached to the base member at a pivot end and slidably connected at a swing end through an elongated aperture on the massager component. The rotating drive arm is preferably driven by a water driven turbine. Additionally, the massager component has at least one convex surface, preferably a roller, which is used to apply contact pressure on a bather and rollably perform the massage as the massager component oscillates.