Description: Part # 100557 is a 3/8" thermal relief valve designed for hot water pressure washers up to 145°F. The valve discharges a small amount of heated water upon sensing a rise in temperature, allowing cool water to enter and cool down the pump. This helps to prevent heat build-up in bypass mode which can cause damage to the machine. An innovative cap design allows flow to be diverted according to operator preference, and the valve may be mounted in the pump manifold, inlet water supply, or bypass loop plumbing. Maximum PSI: 125. Maximum Temperature: 145°F. Inlet Size: 3/8" MNPT. Outlet Size: 1/4" Plastic Hose Barb.