General Pump 100558 Compact Thermal Relief Valve – 1/2" MPT, 145°F for Pressure Washers

General Pump 100558 Compact Thermal Relief Valve – 1/2" MPT, 145°F for Pressure Washers

Protect your pressure washer pump from excessive heat with the General Pump 100558 Compact Thermal Relief Valve. Featuring a 1/2" Male NPT connection and a 145°F temperature rating, this valve provides automatic protection against overheated water during bypass operation.

Its compact design makes it an excellent replacement for pressure washer systems requiring a larger 1/2" connection without taking up unnecessary space.

Specifications:

• Brand: General Pump

• Part Number: 100558

• Type: Thermal Relief Valve

• Inlet: 1/2" Male NPT

• Maximum Temperature: 145°F

• Style: Compact

Applications:

• Cold water pressure washers

• Hot water pressure washers

• Commercial cleaning equipment

• Pressure washer pump systems

• Unloader bypass systems

Features:

• Activates at approximately 145°F

• 1/2" Male NPT connection

• Compact design for easy installation

• Automatically relieves overheated bypass water

• Helps protect pump seals, packings, and O-rings

• Helps extend pressure washer pump life

• Genuine General Pump component

What it does:

When a pressure washer is running with the trigger gun closed, the unloader may place the pump into bypass and recirculate water. If the machine remains in bypass too long, the recirculating water can quickly become hot enough to damage seals and other internal pump components.

When the water reaches approximately 145°F, the thermal relief valve opens and releases the overheated water. This allows cooler incoming water to enter the pump and helps bring the internal temperature back down.

Why it matters:

Excessive heat during bypass operation can contribute to:

• Damaged pump seals and O-rings

• Premature packing wear

• Water leaks

• Reduced pump life

• Costly repairs and downtime

A thermal relief valve is a small, inexpensive component that can help prevent much more expensive pressure washer pump repairs.

The General Pump 100558 Compact Thermal Relief Valve is an excellent replacement or preventative-maintenance part for pressure washers requiring a 1/2" MPT, 145°F thermal relief valve.

Not sure whether your pressure washer requires the 1/4", 3/8", or 1/2" version? Reach out—we'll help you get the right part the first time.