A thermal relief valve is used to prevent pump from overheating. As the temperature rises and reaches 140 degrees the valve will open and release hot fluid allowing the water temperature to decrease and then the valve will close. The valve will open in a range from 2 to 10 seconds depending on how rapid the temperature increase is. To prevent overheating and pump failer the thermal relief valve should be installed in the by-pass line. Internal O-ring seal - Viton External O-ring seal - Buna Stainless steel spring An optional 7469 hose barb can be attached to the 1/8-27NPSF opening of the valve so that a hose can be attached to direct the water flow out the discharge.