We’re teaming up with Greenworks to take a deeper dive into pressure washer performance. There are a lot of bold claims out there, and not every brand is playing by the same set of rules. In this article, I’ll help you understand what the numbers mean, how they can be manipulated, and why choosing a Greenworks TruBrushless pressure washer delivers a more satisfying experience.
Measuring Pressure Washer Performance
When you’re shopping for pressure washers, the two most common ratings you’ll see are PSI and GPM. While they measure different things, both play an important role in cleaning.
PSI stands for “pounds per square inch” and measures the amount of cleaning pressure the pressure washer produces. The more stubborn the debris, the higher the PSI required to get it off. You can think of it as how much strength the pressure washer has.
GPM stands for “gallons per minute” and measures how much water flow is coming out. If PSI is the power of a hammer strike, GPM is how fast you’re hammering. The faster you can swing your hammer, the quicker you sink the nail. Similarly, the higher the GPM, the faster you’re able to apply the water’s pressure and move debris away.
To compare pressure washer performance, you multiply PSI and GPM together to get Total Cleaning Units. Here’s a quick example using a few models from Greenworks’ lineup:
Greenworks GPW3001
3000 PSI x 1.1 GPM = 3300 Total Cleaning Units
Greenworks GPW2702A
2700 PSI x 1.2 GPM = 3240 Total Cleaning Units
Greenworks GPW2500C
2500 PSI x 1.2 GPM = 3000 Total Cleaning Units
By using this formula, you can easily see that the 3000 PSI model has the best cleaning performance. However, if you were debating between it and the 2700 PSI model, you can see that having higher GPM closes the gap even though the pressure ratings are 300 PSI different.
When the Numbers Don’t Add Up
Unfortunately, it’s not always as easy as going to your local home improvement store and multiplying the ratings you see on the boxes. The Total Cleaning Units formula only works when you’re given real numbers to work with. You need the operating PSI and the actual water flow that goes with—ratings that change with different nozzles.
One common way to skew the ratings is by using PSI Max or Peak Pressure. To get the pressure rating, they take the momentary maximum pressure produced, sometimes right at the manifold rather than measuring the normal working pressure through a nozzle.
For the GPM, it can be a similar story. GPM Max can be calculated with no nozzle or even just through the hose to get a higher flow rating than any nozzle will provide.
When you buy a pressure washer based on PSI Max and GPM Max, you’ll never experience anything close to what those numbers claim. Here’s an example from the Westinghouse WPX2700e:
| Westinghouse WPX2700e | Max | Rated |
|---|---|---|
| Pressure | 2700 PSI | 2400 PSI |
| Flow | 1.76 GPM | 1.1 GPM |
Why would you want people to think they’re going to experience pressure that’s 12.5% higher and flow that’s 60% higher than what they’re actually going to get when they’re cleaning?
Certified pressure washers have to deliver real performance within 10% of their claims, but using PSI Max and GPM Max just feels wrong. Be sure to check the packaging and manuals carefully to make sure you know what you’re getting.
Why Greenworks TruBrushless Technology is Better
Greenworks TruBrushless pressure washers are better for a couple of key reasons. For one, you’re not getting jerked around by playing the PSI Max and GPM Max game. You can be confident that the numbers Greenworks reports are within certified tolerances.
Then there’s the TruBrushless technology itself. Rather than simply pushing water through the pump as hard as it can all the time, the motor’s controller adjusts to the nozzle you’re using and optimizes its performance. It’s smarter than a brushed or brushless induction motor, and it makes a difference.
Let’s consider a comparison between two PWMA-certified 2700 PSI brushless pressure washers. The Greenworks GW2700 has its intelligent TruBrushless motor and Ryobi’s RY142711 has a brushless induction motor.
| Greenworks GW2700 | Ryobi RY142711 | |
|---|---|---|
| 15° Nozzle | 2465 PSI x 1.20 GPM = 2958 CU | 2401 PSI x 1.06 GPM = 2545 CU |
| 30° Nozzle | 2043 PSI x 1.26 GPM = 2574 CU | 2401 PSI x 1.06 GPM = 2545 CU |
| 45° Nozzle | 1839 PSI x 1.41 GPM = 2593 CU | 2382 PSI x 1.05 GPM = 2501 CU |
| Turbo Nozzle | 1220 PSI x 1.70 GPM = 2074 CU | 1103 PSI x 1.15 GPM = 1268 CU |
| Soap Nozzle | 126 PSI x 1.96 GPM = 247 CU | 58 PSI x 1.23 GPM = 71 CU |
Looking at these real-world numbers, Greenworks’ TruBrushless technology is able to push better GPM flow at the top, raising the Cleaning Units significantly higher than Ryobi with the 15° nozzle.
Don’t skip the other nozzles, though. The Turbo nozzle is popular for a variety of tasks, and Greenworks is getting more than 800 extra Cleaning Units with it compared to Ryobi. The soap nozzle also applies detergent at a much more efficient rate.
Better yet, performance at this level can replace your need for a model with a gas engine and all the hassles that come with it.
Decision Time
Effective, efficient pressure washer cleaning boils down to a design that maximizes real-world performance. The next time you’re shopping, avoid the games some brands are playing to make themselves look better. Get your hands on a Greenworks TruBrushless pressure washer to get reliable class-leading performance without the fuel, emissions, maintenance, and noise of gas. Your time is valuable, and you work hard for your money, so don’t waste either on an inferior pressure washer.
