Let's start by looking at the different choices you will have to make when buying a power washer:

1. Gasoline vs Electric power washers
2. Hot Water vs Cold Water power washers
3. PSI vs GPM vs CU ( Psi vs Gpm = Cleaning Units )
4. Belt Drive vs Direct vs Gear Driven power washers
5. Portable vs Stationary power washers
6. Wobble vs Axial vs Camshaft Pump
7. Heavyweight vs Lightweight power washers
8. Home Model vs Contractor Model power washers

Gasoline vs Electric: Most power washers are either powered by an electric motor or a gasoline engine. A few are diesel powered. Electric power washers require little maintenance and are very quiet. They require a source of power nearby (because the cord length is limited). They can be used indoors without any problem. You can have electric units with lots of power, but most electrics are small units designed for specific jobs, such as mobile detailing or deck cleaning. Gas units, on the other hand, can be extremely portable. They are designed for outdoor use and can be built to deliver tons of cleaning power. They can be somewhat loud, but your customers expect to hear some noise while you are working. Gas-powered power washers are used for cleaning concrete (called “flat work”), deck cleaning, fleet work, kitchen hoods and ducts, or any other power washing job that requires portability.

Hot Water vs Cold: Most power washers are cold-water portables. Cold water, along with the right cleaners, can do most jobs. Some jobs, like removing heavy grease or stripping off finishes, just go better with a hot water power washer. Hot water will enable you to cut about 30% off the time it takes to do ANY job. The power washing business is all about time, not spending less on your tools. If you have the right tools, you can compete with other contractors and get done with each job in the shortest amount of time. Many new power washing contractors make the mistake of under-buying their tools to save money. Most experienced power washing contractors over-buy their tools and make the difference back in no time with the added power and features. If all you are going to do is clean and seal wood, just buy a cold water power washer. If you are washing anything else, such as houses or hoods or trucks or concrete, consider a hot water power washer. If you already own a cold water machine and want to have hot water, you can call us and buy a “hot box” which will heat the water coming out of your cold power washer.

PSI vs GPM vs CU: First of all, let’s explain the acronyms. PSI stands for Pounds per Square Inch. This is the pressure rating of your power washer. GPM stands for Gallons Per Minute, the flow rate of your power washer. CU stands for Cleaning Units, which is PSI multiplied by GPM. All of these terms refer to the power of your power washer.

To clean effectively, a power washer must provide ‘agitation’ to scrub off the dirt and ‘flow’ to rinse it away. Think of the pressure (PSI) as the agitation that is applied to the surface that you are cleaning and think of the flow (GPM) as the rinsing force that carries the dirt away.

Homeowner power washers tend to run between 1200 and 2700 PSI. Contractor-grade power washers tend to run between 3000 and 5000 PSI. More power means faster work, but more power also means more potential for surface damage. Wood decks, for example, are often cleaned at pressure as low as 300 PSI because 3000 PSI will rip the wood to shreds. Most contractors will settle for 3000 PSI because that amount of pressure is adequate for most jobs. Truth is that most contractors would prefer to have 3500 or even 4000 PSI if they could get it.

GPM is much more important to most contractors than PSI. Since most contractors use cleaning chemicals to do most of their power washing work (the fastest method) their job becomes one primarily of rinsing rather than washing. The cleaners do all of the cleaning, and the contractor rinses the dirt away. When you think about that method, you realize that the more flow you have, the faster the job is rinsed. Therefore, most experienced power washing contractors recognize that GPM is more important to them than PSI.

PSI (power) will help you break the chemical bond between the cleaning surface and the dirt. Once the bond is broken, the extra PSI does nothing to speed up the cleaning time.

The higher the GPM, however, the more surface area a power washer can clean. For example, a 2000-PSI model with a 2 GPM flow rate might clean approximately 5-7 square feet per minute. If the same unit had a 3 GPM flow rate, it might clean 8-10 square feet in the same amount of time.

In this business, contractors sell “the finished job”. The contractor who gets that job done in two hours might be making $50 per hour. The guy who gets the same job done in one hour makes $100 per hour. Which one do you want to be?

Dealers of homeowner power washers like to refer to CUs when they show you a power washer. This number is the result of multiplying the PSI by the GPM. If you have a power washer with 3000 PSI and 4 GPM, you have 12000 CUs. For homeowner power washers, this is a good comparison of the power you are buying. For professionals, CUs have little meaning. GPM is most important, and PSI is less important, and the CU formula makes them both equal. The best solution is to talk to a dealer who really understands what you are trying to pressure wash because he will steer you to the right GPM and PSI for the job.

Belt Drive vs Direct vs Gear Driven: The gasoline engines used for power washers all run at around 3450 RPM. In a Direct Drive power washer that pump is bolted to the engine shaft, so it spins at the same 3450 RPM. In a belt drive unit, the engine is tied to the pump through pulleys and a belt and the speed of the pump is reduced to either 1700 RPM or 1400 RPM. In a gear-driven machine, the engine delivers power to a transmission that in turn spins the pump at a reduced speed (1700 RPM).

Direct drive power washers transfer the vibration of the engine directly to the pump as well.

The faster pumps of direct-drive machines are spinning so fast that they cannot draw water from a tank or a lake very well. They tend to work fine when the water is forced into the machine (like when you hook it up to a hose from the house).

The slower moving pumps (belt driven or gear driven) work less and wear less, so they tend to last many years longer. They will also pull water to the machine from a tank, so your power washer shouldn’t ever be starved for water (a problem that results in destroying the pump).

Gear driven pumps still transmit the engine vibration to the pump because everything is hard-bolted together. This kind of power washer has not become popular since it was introduced because there is obviously one more part to break in the system – the transmission.

Portable vs Stationary: Stationary power washers are used in car washes, factories, etc. They are installed in place and never move. Portable power washers are used by contractors who travel to the customer to do the work. There is a crossover model called a skid unit - a stationary power washer designed to be installed on a trailer so that it can be taken to the customer’s site for the work. The most common power washers for contractors to use are cold water portable power washers (for small residential work) and hot water skid units (for large commercial work or high-volume residential work).

Wobble vs Axial vs Camshaft Pump: Since your pump is the heart of your system, it is critical to understand what you are buying. Every pump manufacturer makes several grades of pumps – Good, Better, and Best.

The Wobble design requires a piston to push against the pressure in the pump and the pressure of a spring. This is an inexpensive design to build, but it is relatively inefficient, too. This is the design found on most homeowner power washers. It is designed to work for limited hours at a time and very limited hours per year, which is OK for a homeowner but doubtful for a contractor who wants to pressure wash every day. Wobble pumps tend to last for around 300 hours before needing extensive service or replacement.

The Axial design is similar to the wobble design with a couple of important differences. Most axial pumps have larger oil reservoirs and bearings, which allow them to be used for longer periods of time and more hours per year. They still are inefficient (like the wobble) but several lower-priced contractor-grade machines work fine with the axial design. Axial pumps tend to last for about 600 hours before needing service.

The Camshaft design delivers the most power and durability of all these designs. It uses connecting rods on a cam with large bearings like a car engine, so it runs cooler and lasts longer. It is able to hold up to continuous use for hours and hours as long as it is kept cool. Cam pumps tend to run for 1000 hours before needing service, and tend to last 2000 hours before needing extensive service or replacement.

Heavyweight vs Lightweight: If you are buying a portable power washer, it makes sense to pay attention to the weight of the unit. After all, you are the one who is going to lug it all around and move it into and out of your truck. Aluminum frames can be fragile, and steel frames can be heavy, so talk to your dealer about how you are going to transport the power washer. He may be able to steer you to a good solution for your needs.

Home Model vs Contractor Model: The final choice for you to think about is durability. We have already discussed the difference in pumps, even from the same pump manufacturer. The cheapest power washers usually have the cheapest pump, which won’t hold up well for most contractors. There are other considerations that you need to think about, too.

The finish of the machine can be very important. Powder coating holds up better and lasts longer than painted frames. Steel frames rust. Aluminum or stainless doesn’t. Aluminum can be bent, steel is very rigid. This particular choice will vary depending on the power washers preference.

For power washers that will be used at least 20 hours per week and sometimes up to 8 hours in a day, the lower priced machines just won’t last very long. They come with inadequate parts throughout, such as the unloaders, pumps, and even the engines. Just because it says “Honda”, for example, doesn’t mean that all Hondas are the same. This is where Grandpa’s “you get what you pay for” saying really is true.

If you buy a $900 power washer and you get six months use out of it, that purchase cost you $150 per month. If you bought a name brand commercial-grade machine of the same specifications for $1600 and you got 5 years of use from it, that purchase cost you $27 per month. Which one is less expensive?

Let me relate some of my own experiences. As a power washer dealer, I see homeowners dragging in dead machines that are only a few months old every week. These machines cost more to fix than to replace, so my ‘boneyard’ is full of discarded homeowner units.

I recently sold two old power washers that I used when I was a contractor and didn’t want any more. They were each 12 years old and each ran like a top. One had needed only routine maintenance over it’s life. The other had to have the pump completely rebuilt about three years ago. They were both belt-driven units with AR pumps and Honda engines. I paid about $1500 for each and sold them for about $300 each. When I added up all of the maintenance costs and the purchase price and then subtracted what I got for them when I sold them, those power washers costs me about $16 per month to own. Is there a better deal than that anywhere?

If the bottom line for you is how much cash you have to fork over right now, consider an alternative. A reputable dealer can get you into a quality power washer on a lease or finance contract. In the long run, you are better off with the better power washer. You will spend less of your cash today, and less over the life of the  even with the interest added on.

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