A spa is provide with a heat pump for both heating and cooling the water contained in the spa tub. The heat pump uses the existing water pump of the hydrotherapy system to circulate the water through the water heat exchanger of the heat pump. Condensation produced by the heat pump is pumped into the spa tub. Components of the heat pump and water pump are acoustically isolated for noise reduction. Electronic noise reduction may be implemented. Co-generated heat is used to heat the air to produce warm therapeutic bubbles and to feed an ozonator. In addition, an auxiliary electrical resistance heater is arranged in combination with the heat pump for rapid water heating.