Thermal relief valves 'trip' at 145° or 190° and allow water to pass through and cool your pressure washer pump. Both the 3/8" and the 1/2" trip at 190° and the 1/4" trips at 145°. These prolong pump life by limiting damaged caused by overheating.
Landa Stock #
9.803-670.0 1/2"
8.707-250.0 3/8"
9.804-025.0 1/4"