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How long can you run a pressure washer?

When it comes to using pressure washers, there are dos and don’ts every homesteader should know. To people who use these machines to render commercial cleaning services, note that machines can outlive their usefulness sooner than expected if you use them carelessly. Pressure washers, therefore, can develop mechanical problems or become completely grounded when you fail to follow instructions in the user manual to the letter.

How long can you run a pressure washer?

You should not run a pressure washer (except professional equipment) for more than five minutes. While the duration may vary from model to model, it should be between 3 and 5 minutes. Leaving your pressure washer running for more than five minutes can result in overheating.

We bet you don’t want to end up spending so much money repairing a grounded machine because of carelessness.  While some situations such as receiving a phone call in the middle of a cleaning routine are unavoidable, the fact that they will distract your attention means you should not use a pressure washer in by-pass. The best advice we can give therefore is to shut down the unit before attending to anything else lest the pump gets damaged. 

Most importantly, take note of the gallons per unit rating (GPM) of your pressure washer to ensure there is a sufficient flow of water through the unit.  If, for example, the unit has a pump rating of 5 gallons per minute, ensure the water supply is 5.0 GMP or more. Anything less will result in cavitations, a phenomenon where a trigger gun develops a pressure surge.

In worse conditions, permanent damage to the pressure washer may occur. The catch is that these machines need constant water supply to work efficiently. While water is not a lubricant, ensuring there is enough flow through a pressure washing unit guards against overheating. 

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Do pressure washers overheat?

Pressure washers can overheat, and it is not a good thing. With this, the next question that comes to mind is what causes overheating in power washers? Well, based on our experience, it can happen because of the following reasons:

  • Hot water: When pumping hot water into pressure washers designed to use cold water.
  • A mechanical problem in the heating system may result in excessive heat build-up in the unit.
  • Failure to pump enough water into the unit. You should pump water into a pressure washing unit as per GPM requirements. Always check the pump rating for directions.
  • Time: Leaving your power washing running for more than five minutes is likely to cause overheating, something that causes damage to the pump.
  • Gas problems: In gasoline-powered pressure washers, excessive fuel pressure causes overheating. It is, therefore, advisable that you check the manufacturer’s fuel pressure recommendations before powering on the unit.
  • Wrong use: Other causes of overheating in pressure washers are, improperly installed burner nozzle and wrongly set unloader.
  • Thermostat: In some cases, a thermostat in pressure washers may develop problems, resulting in unprecedented overheating.

Diagnosing pressure washers for overheating

You should feel your power washer heat when the unit is in by-pass. A surge in pump pressure and very hot water are common signs of overheating units. The best advice we can give is, therefore, to stop using the machine and seek help from a repair professional. Heating problems in power washers are mechanical, thus, you should not risk using the system should the problem persist.

You should also not try to fix the issue, especially when you are not sure on how to go about it. We discourage guesswork when it comes to troubleshooting overheating power washers because you could damage the unit more.

Role of a thermostat in regulating pressure washer temperature

A thermostat is a vital component in most, if not all machines. It is a fitting that regulates temperature so that it does not go above or below optimal. You should, therefore, understand how a thermostat in your power washer works to aid your troubleshooting of the overheating problem.

Pressure washers can have either adjustable or non-adjustable thermostats. Naturally, water will heat above the optimal temperature. Diagnosing a thermostat when heating persists will help you rule out or confirm a glitch. Fixed thermostats maintain the desired water temperature by cycling the burner nozzle on and off.

You should set the thermostat to the desired temperature for it to work effectively. Do not worry if water temperature increases and decreases at intervals. But to realize constant water temperature, reduce the heat output of the burner nozzle. 

On the contrary, pressure washers with non-adjustable thermostats present a different challenge. Because the burner nozzle will be firing non-stop, it is expected that water temperature will increase at a constant rate when using the machine. If that is the case, use a safety switch to control overheating. It works in the sense that as soon as you achieve a preset water temperature, the safety switch goes off.

Do electric pressure washers overheat?

Electric pressure washers can also overheat. It can happen if you leave the unit running when not in use. This often results in the pump getting running hot and finally in pump damage. Another cause of overheating in electric pressure washers is a glitch in the power supply circuit.

From damaged capacitors to faulty fuses, excess heating in electric power washers is often a major cause of worry because you are likely to suffer an electric shock.  If you cannot run a diagnostic procedure to identify the cause of the problem, we recommend consulting a professional service provider for help.

Pressure washers protection against overheating

Pressure washers have some built-in protection mechanisms against overheating. Gas-powered pressure washers have a thermal release valve that will open when the temperature reaches a dangerous level. I recommend trying to avoid such high temperatures by giving the pressure washer time to cool down regularly.

Electric pressure washers use a different mechanism against overheating. They have a switch built into the trigger that only makes the motor work when it needs to. This makes the chance of overheating for electric pressure washers smaller. But also for electric pressure washers, I recommend working intermittently. Give the machine some time to cool down, and never let the motor run for an extended time.

How to prevent a pressure washer from overheating

There are several tips that can help against your pressure washer overheating:

● Use the pressure washer intermittently to prevent overheating

This applies both to gas and electric pressure washers. Do not use them for an extended period. For electric pressure washers, this means that you spray for 10 to 20 seconds, and then release the trigger. This will stop the motor. Wait for 5 to 10 seconds before continuing.

This is usually the time I move to a slightly different position. During this time the pressure washer pump can cool down.

For gas pressure washers this applies as well. Only in this case, I additionally recommend stopping the engine when you notice the pressure washer it is getting really hot. I do this after around 20 to 30 minutes, and stop if for 3 to 4 minutes. If the pressure washer is in the sun, and I’m using high pressure, I even recommend a slightly shorter time.

● Use a lower pressure to prevent the pressure washer from overheating

When you use lower pressure, the pump will heat up less. In many cases, such high pressure is not needed. The higher the pressure, the hotter the pump will get, and the quicker it will heat up.

● Use adequate water pressure to prevent the pressure washer from overheating

When the water pressure is not sufficient, the pump will not get enough water to cool it down. A pressure washer pump uses the water to cool itself and needs a certain minimum water pressure to function properly.

This minimum water pressure will differ from model to model and is something you can find in the user manual. It will be mentioned as gallons per minute (GPM). Most pressure washers mention a minimum of 2 GPM. They mostly will work with a lower pressure, but this means a higher chance of overheating.

Tip: If your location has lower water pressure, ensure that you do not use the pressure washer for too long. Give it enough time to cool down. There are also pressure washers that are rated for lower minimum water pressure.

● Do not use the pressure washer in the sun to prevent overheating

When the pressure washer itself is in the sun it can heat up much quicker. Try to move the pressure washer to a cooler location, in the shade. This can be under a tree, or beside another object.

Is it bad to leave a pressure washer running?

Generally, it is bad to leave a pressure washer running for more than five minutes. If you cannot switch it off after a minute or three, do not idle the unit for more than five minutes. Leaving your pressure water running will damage its inner workings because as temperature builds up, the pump is at risk of damage.

The catch with pressure washers is that pulling a trigger gun ensures a constant flow of water in and out of the unit at set GPM. Constant flow means inner components of the machine remain cool, usually at an optimal temperature of 60 degrees.

However, when you push the trigger, but leave the engine running, the flow of water stops. The result is water recirculation in the pump, often under high pressure while by-passing pump outlet. As recirculation continues, water keeps heating up.

Imagine a situation where water temperature in the pump head rises to 145 degrees. The health of your power washer would be at stake if the water continues to heat up. If you do not switch off the system within five minutes, the worst happens. Overheating due to water recirculation in pressure washer pumps damages the unit.

Leaving pressure washers running/idling is the last thing that should cross your mind. If something interrupts your cleaning routine, especially when using a power washer, shut it down. But if it’s a brief interruption that would not last more than three minutes, pull the trigger gun to let in freshwater. The pump should cool down within a few minutes.

Overheating in pressure washers will immediately damage the pump. Other problems such as the following will also begin to manifest:

  • O-rings: Faster wear and tear of o-rings.
  • Water seals in the pump and other parts of the machine will also begin to wear and tear sooner than expected.
  • Warping of some components may occur, especially on the sides with low pressure.
  • Valves will also become distorted.

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Protecting pressure washers from thermal damage

Thermal damage in pressure washers will double the cost of repair and maintenance. You should, therefore, avoid it at all costs. Apart from not leaving the unit idling in by-pass/running for more than five minutes, we advise installing a thermal valve.

A thermal valve will open when the pump heats up to 145 degrees. The opening valve lets out heated water. Fresh cool water then goes in to cool down the system. You should always ensure that the thermal valve resets correctly after opening. If your power washer has a stainless steel plunger, there is no cause for alarm. The ceramic coating on the steel plungers usually conducts heat to prevent overheating.

Final Thoughts

Pressure washers are bound to overheat provided you leave them running for a few minutes. It is because, by design, water recirculation takes place in the pump head when the trigger is off. And because overheating is a leading cause of damage to machines like pressure washers, you run the risk of damaging your most handy cleaning machine. If you are planning to do something midway a cleaning a routine, do not leave a power washer in by-pass mode.

For a novice looking to purchase a power washer or use one for the first time, we advise reading the user manual. If the pump is rated 5.0 RPM, ensure you pump 5 gallons of water per minute to avoid overheating. Less water going through the system means some components will overheat, causing warping in low-pressure zones.