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Useful Information on buying a pressure washer


What you need to know before buying a Pressure Washer

October , 2018

Pressure  washers are a relatively new tool.  Over the last ten years the quality  has increased as prices have become more affordable.  The cleaning  ability of a pressure washer is great, removing dirt, grime and algae  efficiently and effectively.  Some may consider this item a luxury  purchase, but a pressure washer can greatly increase the ability to  maintain and clean your property, saving time and money, and giving it  greater value.  The goal of this buying guide is to help you understand  what a pressure washer does and what you need to look for when deciding  to purchase one for yourself.

Before we start talking about buying pressure washers we need to define some basic ratings:

HP (Horse Power) -  How much power the engine can generate.  This rating is important  because it directly relates to how much volume and pressure the pump can  produce.

GPM (Gallons Per Minute) or Litres per Minute- The volume of water available for cleaning.

10 litres a minute = 2.5 Gallons per minute

12 Litres a minute = 3 Gallons per minute

14 Litres a minute = 3.5 Gallons per minute

15 Litres a minute = 4 Gallons per minute

21 litres a minute = 5.5 Gallons per minute

CPU (Cleaning Power Units) - This is one of the least understood, yet the most important rating for pressure washers. To determine the CPU rating of a pressure washer, you multiply the PSI by the GPM. The greater the CPU the greater the ability the machine has for cleaning deeply and effectively. Often a consumer is so focused on the PSI of the machine that they do not take the time to look at the CPU. For example, a pressure washer may have 2800 PSI and 2 GPM giving it a CPU of 5600. Another pressure washer has only 2400 PSI but has 3 GPM giving it a CPU of 7200. In this example the lower PSI machine has 25% greater cleaning power than the higher PSI rated machine. The result is that the 2400 PSI machine will be able to clean an area 25% faster than the 2800 PSI machine. CPU is sometimes called Cleaning Unit (CU) or Cleaning Power(CP). The CPU rating allows the consumer to compare different machines effectively.

Now  consider this, a garden hose will be about 6 GPM and 10 PSI giving it  60 CPU.  With a standard spray nozzle attached to the garden hose you  can get around 5 GPM at about 40 PSI generating 200 CPU.  We all have  seen the difference of how much more effective a simple spray nozzle is  at cleaning dirt off of surfaces.  Trying to clean your driveway with  your garden hose spray nozzle generating 200CPU is fairly ineffective.   However, if we take a midrange pressure washer a 2 GPM and 2500 PSI  (5000 CPU) this is a   25 times increases over a spray nozzle.  A  commercial pressure washer at 4GPM and 4000 PSI is an incredible 16,000  CPU.  It is not difficult to imagine the difference in efficiency.

Components of the Pressure washer

Every  pressure washer is made up for four main parts.  It is important to  have an understanding of the components and what they do.

• Pumps

There  are three different styles of pumps: Wobble, Axial & Triplex.  I  could go into explaining each pump’s inner workings but that’s less  important than understanding that there are various qualities within  each style.  Wobble is generally considered to be and built as an  economical pump, Axial as a midrange, and Triplex are generally for  higher end, commercial pressure washers.  It’s important to make sure  that if you purchase a commercial pressure washer, it’s mated to a  Triplex (piston) pump so that your pump can handle a higher horsepower  commercial motor.

Drive system

Direct  drive systems are the most common.  Compared to a belt drive system  this is a much simpler method needing less parts and space resulting in a  more compact design.  Direct drive is also considerably more economical  than an equivalent rated belt drive machine.

Belt  drive systems are typically seen on more industrial platforms.  The  belt drive turns at a much lower rpm (1725rpm vs 3450rpm of a direct  drive).  The belt absorbs engine vibration which will wear out a pump  faster.  Since the pump turns at a slower speed all the pistons and  valves in the pump will be larger.   All this adds up to a cooler  running machine that will last considerably longer than an equivalent  direct drive version.  However, there is slightly more maintenance and  considerably more dollars involved (10-30% more).  If you are using your  pressure washer for industrial applications and expect to work with it  almost every day, then this is what you want.  However, an equivalent  direct drive machine will have the exact same performance for a lot less  money.

• Engines & Motors

The  engine is the part that powers the pump.  The more powerful the engine  (rated in HP), the greater the PSI and GPM that can be produced.

Electric Motors are  very low maintenance and fairly quiet.  There is also no exhaust so  they can be used indoors or poorly ventilated areas.  Your typical  electric pressure washer that is 110v and 15a will be fairly light duty  because the motor is not strong enough to generate much PSI or GPM.

Gas Engines generate  much more power than most non-commercial pressure washers and are a lot  more mobile because they do not need to plug into an electric power  source. Since gas engines are generally more powerful, the pump can  generate considerably more PSI and GPM so that they can clean faster and  deeper than any 110V electric pressure washer could.  However, they do  take a little more maintenance and cost more to operate.  They must be  used in well ventilated areas because of carbon-monoxide fumes.  All  4-cycle engines operate on regular unleaded gasoline.  It is strongly  recommended to use fuel stabilizer if you do not use your machine often  (or winterizing it).

When  it comes right down to it, the two most important things to ask about  the engine is how much horsepower it has and how many hours it is rated  for.  The better quality the engine, the longer it will last.

• Accessories

Without these, your pressure washer is fairly useless.  It would be like having a drill without any drill bits.

Pressure  Washer Hose: Everything starts with the pressure washer hose.  You will  usually want 50 foot lengths as most people tend to find 25 foot to be a  too short for a lot of applications.  Make sure you get a quality hose  with the proper PSI rating to match your machine.  A poor quality hose  will breakdown faster, is more susceptible to leaks and kinks and will  usually be less flexible and harder to work with.

The  Lance: Every pressure washer should come with one.  You can change the  spray pattern with the different nozzles at the end depending on the  application. From very narrow spray to generate cleaning force at the  tip for deeper cleaning to a wider spray that has cleaning force but  covers more area.

Some very useful attachments include:

Dirt  Blaster: This is a nozzle that goes on to the end of your lance.  It  has a narrow spray but spins in a circular motion very rapidly so it has  the effect of a fan pattern.  This attachment is great because it can  quickly cleans hard surfaces very well and when used properly avoid the  ‘tiger stripping’ effect on your driveway that happens with conventional  spray tips.

Extension/Telescoping  lances: A telescoping lance that’s adjustable up to 24′ in some cases  for cleaning out of reach areas.  This is a great benefit if you need to  reach up high so that you can avoid trying to pressure wash while  standing on a ladder.

Gutter  cleaners: This is a simple hooked piece that goes on the end of your  lance.  It lets you get into your gutters to clean them out.  Be careful  though with high pressure machines, if you jam them into your gutters  carelessly the pressure can strip out the caulking in your gutter joints  (especially in the corners).

Flat surface cleaners / Rotary: These  are a great addition also.  They are a surface cleaning attachment with  two rotating nozzles inside.  With a diameter of 12″ to 36″, these  greatly speed up the cleaning of large flat areas.

Ball  Valve: This is one of our favorite items.  It is a shut off lever that  you put at the end of your hose.  So if you want to switch attachments  you can turn off the water pressure/supply without having to walk back  to your pressure washer and turning it off.


Detergents  can greatly increase the speed of cleaning and help remove tough  stains.  Most pressure washers come equipped with a venturi tube that  will draw in the detergent from a bottle or pale and add it to the water  stream at low pressure, downstream from the pump.  The detergent should  be first applied at low pressure, and then given some time to break  down the stains.  After, it should be rinsed off with a normal high  pressure spray.

It  is strongly recommended to use only pressure washer specific  detergents.  Using wrong detergents can clog your system and potentially  damage your pressure washer.  Also be aware of the chemicals you’re  spraying, making sure they are environmentally safe.  Special permits  may be needed for certain heavy duty industrial chemicals.

Final Words

When  it comes right down to it, you need to buy a pressure washer that fits  your application.  There are many different types of pressure washers  from very low end electric machines to extremely powerful industrial  machines.  Before you buy a machine you need to sit down and determine  what you plan to use it for.  One of the most important questions is  “How much will I be using it?” If you are a homeowner you will probably  use it two or three days per year putting 20 hours of work on your  machine per year.  In this case getting a machine rated for 500 hours  will last you (if properly maintained) 25 years.  However, if you are  working with it as part of your business, you will want something rated  for 2000 hours or more.

Also,  you need to determine what applications you will be expecting the  pressure washer to perform.  If you are looking at doing light  occasional chores, such as cleaning smaller areas, cars, lawn equipment,  dirt, algae then you can get away with an entry level pressure washer.    If you are expecting to do more frequent work and bigger jobs such  house siding, large areas of concrete, farm equipment then you would  want a machine than can produce 12,000 – 16,000 CPU.  Commercial and  contractors will want something rated around 25,000 CPU to do the  extremely demanding jobs and to speed up the cleaning process with the  extra power.

Finally,  plan in advance what attachments you will want in the future and make  sure that the pressure washer you buy has enough power to support them.


How To Choose A Pressure Washer

Pressure washers, with their hot- and cold-water blasting cleaning capability, are growing in popularity at the industrial, commercial and now even homeowner level largely because they’re “money machines.” 

SAVE TIME: Pressure washers put water under pressure so they clean 4 to 5 times faster than a garden hose or other traditional methods.Begin your search by focusing on 3 key questions: what, where, how long?

1. Grease and grime usually require cleaning by a hot water pressure washer

2. Gasoline-powered models are more flexible, but confined to the outdoors

3. Rugged components pay off in maintenance costs and longevity

SAVE LABOR: Less cleaning time means less labor. Less labor means more productivity and less overtime by employees. It all translates to more bang for the buck.

SAVE WATER: Surprisingly a pressure washer uses much less water than other cleaning methods. For instance, the typical garden hose puts out between 6 to 10 GPM (gallons per minute). The typical pressure washer uses between 2 to 5 GPM - a 50% to 70% savings in water usage.

PROTECT YOUR INVESTMENT: washer helps protect and extend your investment in machinery, trucks, and other equipment, to say nothing of how a company’s public image is enhanced when shiny rigs—or “rolling billboards”—go down the highways.

So how do you make sure you get the right pressure washer for your cleaning job?

By asking three simple questions you’ll ensure you make the right choice: (1) What are you cleaning? (2) Where are you cleaning? and (3) How long will you be cleaning?

What are you cleaning?

All pressure washers fall into one of two categories: hot water or cold water. If you’re cleaning engines, automotive parts, or anything else with oil or grease, your best option is a pressure washer that generates hot water. Like the dishes in your sink, hot water cuts grease and grime; cold water only pushes it around 

(It’s not unusual to hear hot water pressure washers referred to as steam cleaners or steam jenneys. While there are a few applications--such as detailing an automobile engine that require steam, it has been proven over the years that hot water under pressure is a much more effective method of cleaning than steam. Some pressure washers still have a “steam combination” option where the hot-water flow is restricted in order to create a “wet steam” effect.)

On the other hand, if you’re simply blasting away soil, caked-on mud, or even stripping paint, a cold-water pressure washer will work just fine. In fact, an estimated three-fourths of all pressure washers purchased today are of the cold-water variety. A cold-water pressure washer with the right detergent often can solve most cleaning problems.

Where are you washing?

That may seem to be a silly question, but whether you’re cleaning indoors or outdoors can make a huge difference in your cleaning options, many of which can dramatically impact your wallet.

you need portability? In other words, do you need a pressure washer with wheels so you can move it around or are you cleaning equipment and vehicles that can be moved up close to your pressure washer?

Are you cleaning on a job site or do you have easy access to electricity? 

Here’s why those questions are so important:

If you’re cleaning indoors, you’re limited on your energy sources. For instance, indoors you’re confined to using an electric motor to drive the high-pressure pump. The electric motor limits your portability because you’re constantly “tethered” to an electrical outlet.

If you need hot water indoors, you’re further restricted to the type of heating fuel you can use because of fumes from fossil fuels. You can use electricity (expensive), natural gas (requires hard plumbing and must be vented to the outdoors) or LP gas (liquid propane—a popular source but there is a very limited selection of LP-heated models on the market).

If you’re cleaning outdoors, you now have many more options. You can operate a pressure washer powered by electricity or gasoline, the two most popular power sources. Typically, the electric-powered models are more economical, but the gasoline-powered pressure washers are a lot more portable (no electric cord).

For outdoor cleaning with hot water, you can heat the water with diesel (the most popular), kerosene and fuel oil in addition to the “indoor energy sources” of electricity, natural gas and LP gas. The most popular outdoor hot water pressure washers are powered by electricity (economical) and heated by diesel (economical and plentiful).

However, another outdoor hot water model that is quickly gaining in popularity is one that is powered by gasoline (economical and plentiful) and heated by diesel. It is extremely portable and self-contained. All you need is water and you can clean most anywhere.

Speaking of water, pressure washers typically are fed by a garden hose from a spigot. However, most pressure washers are also capable of drawing water from a large tank or bladder, which makes on-site clea

Finally, how long will you be cleaning?

This question reaches the heart of how much quality you need in your pressure washer, which also affects the price tag. You get what you pay for or, as some say, you only pay once for quality. 

If you are operating a pressure washer for less than five hours per week, you will probably be satisfied with a less expensive model available in catalogs and do-it-yourself stores. But don’t count on much service or warranty support.

If you are operating a pressure washer from 5 to 20 hours per week, you will find some mid-range models that are typically identified by a direct-drive pump and a bare-bones design.

For those who are serious users--washing for more than 20 hours per week, you will be dollars ahead to invest in quality.

So how do you identify quality? 

Most pressure washers, regardless of brand, have similar components. They have an engine or motor that turns a high-pressure pump. Hot-water models also have a burner that heats the water as it races through a coil made of pipe or tubing.

The quality differences are not always obvious, but significant nonetheless. Here are the questions to ask in order to identify quality in a pressure washer:

Is it belt-drive or direct-drive? 

A high-pressure pump does not turn on its own; rather it is driven by an engine or motor. Pumps generally turn at 1100-1500 RPM while gasoline engines turn at a rate of 3000-3600 RPM (1450-3450 RPM for electric motors). 

There are two predominant ways to connect the pump to an engine or motor: directly (direct-drive) or with a pulley and belt (belt-drive).

Direct-drive pumps are more compact, helping to keep the weight and cost down. Today’s direct-drive pumps have been engineered to hold up very well, even under constant use. The weakness, of course, is that a pump turning at 3600 RPM will wear out faster than a pump that turns at 1500 RPM.

On the other hand, a belt-drive pump, configured with a pulley and belt, allows the pump to turn at the slower rate (usually 1500 RPM). The belt also dissipates the build up of heat and absorbs vibration from the engine. The ultimate benefit, of course, is that downtime is minimized and the pump’s life is extended saving you money in the long run.

There are other features that say “quality” in the engine-pump connection. Dual belts and V-groove belts, which are notched and cogged, run cooler and provide a better grip for a more efficient performance. Some models mount the pump on a two-bolt adjustment rail so it is easy to tighten the belt tension and keep the pump operating at peak levels.

Is the pump tri-plunger ( Triplex ) or axial?

All quality pressure washers will have a tri-plunger pump, or a pump that is turned by a crankshaft, connecting rods and three ceramic plungers. The rotary design of the axial pump is known for being low cost, high maintenance and its life is typically rated for no more than 800 hours. On the other hand, quality tri-plunger pumps usually have warranties of up to five and seven years.

Does it have high pressure or high volume? 

A little known secret is that there is more cleaning power in a pressure washer’s volume (gallons per minute) than in its pressure (pounds per square inch or PSI). A pressure washer with 2 GPM and 3000 PSI won’t clean as fast as a pressure washer with 4 GPM and 2000 PSI. The first pressure washer delivers 6,000 cleaning units (2 x 3000) as compared to the second pressure washer’s 8,000 cleaning units (4 x 2000). Despite what you see in advertisements or on a product label, volume is the deciding factor and a quality pressure washer will provide the proper balance of volume and pressure.

Is the engine or motor size correct?

As mentioned above, it is not uncommon for a manufacturer to sell the “sizzle” of high pressure over the more important water volume. A reliable rule of thumb is to review the flow rate along with the size of engine or motor. For industrial cleaning, you will want a pressure washer with at least 4 GPM and is driven by an engine with a minimum of 11 HP (5 HP for an electric motor). For a quality hobby pressure washer, you’ll want a minimum of 2 GPM driven by at least a 5 HP engine (2 HP electric motor).

Is the frame or chassis solid? 

Steel is steel, so most frames or chassis will hold up fine over the life of a pressure washer. However, there are questions you can ask that will determine just how much quality is in a pressure washer frame or chassis.

Is the frame Galvanized Rust proofed for life ?

Are the seams reinforced with a weld?

Is the paint an epoxy powder coat for long-lasting, all-weather protection?

Does the chassis have shock-absorbing feet to cushion the vibration and to prevent the pressure washer from “walking” while in operation?

Is the hose of high quality?

Of all the critical components on a pressure washer, manufacturers will often scrimp here to save a few dollars. Shiny, thermoplastic hoses are the lowest quality. High quality hoses are made of a rubber compound reinforced with steel wire. A hose rating should be imprinted on the hose itself. A single-wire hose (R1) is typically rated for up to 3000 PSI while a double-wire hose (R2) is usually rated for 4500 PSI or higher.

Despite their simplistic design, be assured that not all pressure washers are created equal. Nonetheless, you can have confidence in making the right choice when you ask the right questions.