Pressure Washer Thermal Relief Valve 1/4″ NPT 3/8″ NPT Thermal Relief Valve by | Jul 24, 2026Product Size: 3/8″ NPT, 1/4″ NPT, G1/4″, G3/8″. ✨ Thread Options: Available in NPT 1/4″ and NPT 3/8″ tapered pipe threads to fit common pump head ports. ●Compression Fittings. ●Solenoid Valve. ●Flow Sensor.