Pressure Washers Bypass

When operating your pressure washer make sure that you do not leave the pressure washer in bypass for more than a few minutes. Power washers that have a trigger gun control on them most likely have an unloader or bypass valve. The unloader or bypass valve allows the pump to continue running after the trigger gun is released by recirculating or bypassing the water back through the pump via the unloader/bypass valve. When the water is recirculating through the pump, the water will build up friction heat and can reach temperatures beyond 180 degrees F within a few minutes and start to do major damage to the pressure pump, seals, check valves, unloader/bypass valve, ceramic pistons.

A couple ways to help prevent leaving a pressure washer in bypass is either open the trigger gun after 2 minutes of bypass time(this will allow fresh cooler water to displace the water that was in bypass) or shutdown the power washer after 2 minutes. 

If you are purchasing a new pressure washer, there are a few options to consider that will help keep the machine from running in bypass for long periods of time.

Thermal Relief Valve-This affordable valve can be plumbed into the bypass line and when the water reaches a set temperature (around 140 degrees F), the valve will open and spill out the bypass water and replace it with fresh cooler water. Once the valve cools off, the thermal relief valve will reset itself.

Time Delay Shutdown-Mostly used on electrically powered pressure washers. When the trigger gun is released, a timer relay is activated to shutdown the electric motor after a set period on time. To restart the power washer, the operater must turn the pressure washer back on at the control panel or remote panel.

Automatic Start/Stop-Mostly used on electrically powered pressure washers. When the trigger gun is released, a pressure switch, vacuum switch or flow switch is activated to shutdown the electric motor immediately. To restart the power washer, the operater open the trigger gun, the switch is deactivated and the electric motor starts.

Clutch Driven System-Can be used on an electric or gas engine powered pressure washer. Used only on a belt driven power washer. When the pressure washer is turned on only the motor or engine turns, until the trigger gun is opened then a micro switch will engage the pump clutch. The pump will only turn when clutch is engaged, this keep the pressure washer from going into bypass.