Proven Part 11/4″ Thermal Relief / Relief Valve For Pressure Washer Pumps by | Jul 24, 2026Protects the pump from overheating causéd by recirculating water. 1/4″ THERMAL RELEASE / RELIEF VALVE. Thermal Relief Valve. Installs in bypass line or Thermal Port On Inlet Side Of Pump. Troy-Bilt Pressure Washer Models.