Tip & How-To about Garden

What is a Thermal relief valve?

The thermal relief valve is a valve that opens when the water inside your pump gets too hot. When you are not pulling the trigger on your gun, the water is circulating inside the pump. After a little while the water starts getting hot from the friction of the moving parts. When the water gets too hot, the heat starts to damage the water seals. What a thermal relief valve does is, at about 145 degrees it opens up dumping the water inside the pump on the ground. As the water pours out, new cool water flows in from the garden hose, cooling off the pump. I personally recommend a thermal relief valve to everyone I sell pumps to. Not all pumps come with a thermal relief valve. For the price (between 10 and 15 dollars) they will save you a lot more than they cost.

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Why is water continuously coming out of the thermal relief even when the water is cold?


if your pressure is satisfactory then you will need to replace the thermal relief you can plug the port as long as the pump is unloading fine when trigger is released an get a replacement asap thermal relief valve will open when the gun is released for a long duration of time over three minutes.detergent valve inside the barb you may have to assist the ball bearing inside it might be stuck to the o-ring and the siphon it produces is not sufficient enough to cause separation.you can insert a nail small enough and slowly insert it inside the port til you feel it separate.

Aug 18, 2014 | Garden

1 Answer

Pressure Washer


any leaks from connection at pump to gun and wand assembly if so the valve is detecting leakage and open up again without u squeezing trigger it builds up in the head.if your trigger gun is leaking internally then you will need to replace the gun this unit uses a trap pressure unloader valve

Jul 15, 2013 | Garden

1 Answer

Portercable Pressure Washer Model PCH2401


when the trigger for the wand is not pulled , there is a pressure relief valve that bypasses the water in the pump and so there is no pressure until the trigger is pulled again.
with the pump getting hot and not being able to pull the motor to restart, it indicates that that pressure relief valve has jammed ( faulty ) and the pump is running at full pressure all the time
That will heat the pump and stop the engine from restarting
That valve is where I would start looking for a problem

Apr 25, 2017 | Porter Cable Garden

1 Answer

2-yr old troy-bilt pressure washer with honda gcv160 engine. seems to run well, but when trigger is pulled get full pressure for less than 5 seconds before reducing to house water pressure. when left running, looks a black plastic pressure relief valve starts blasting hot water. appreciate whatever insight you can give. Thx


It sounds like an air lock. Try this: With the machine off, connect the hose to the washer and let it run for several minutes to get all of the air out of the hose, and to purge any air out of the pump. Shut off the water, and connect the high pressure hose, but not the gun. Let the water run for several minutes. stretch out the HP hose and make sure that the air is displaced. Shut off the water, connect the gun, and purge as before. Now crank it washer up. As quickly as safe to do so, open the trigger to keep water moving through the washer. It should come up on pressure very quickly. It is better during normal operation to keep water moving through the system. When I am through for a while, I shut down my washer, but leave the trigger depressed to allow the pump to stay full of water, and cool. This prevents further problems when I restart it.
Hope this was useful.

Regards --W/D--

Jul 17, 2009 | Briggs & Stratton Garden

1 Answer

Troy Bulilt Pressure washer with no pressure


sounds like the spring that hold the relief ball is to soft and when heated it releases..if it has a manual adjustment on it you might try to add a few turns to increase the spring pressure also check and make sure the pump has the proper level of oil in it ..if it is low in oil it will run extremely hot and the relief spring will fail

May 27, 2009 | Air Tools & Compressors

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