No...there is not a thermostat in that housing,and you CANNOT use one on that type of setup (no water pressure bypass valve = blown head gaskets).Water temp can only be controlled by adjusting the main valve at the pump. I am as well as many other jetters are useing a REX DUAL TOWER THERMO. setup with a pressure relief valve in the housing.Get a REX catalog,there's a diagram showing how it functions.