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.
PSI (Pounds Per Square Inch) - The amount of water pressure between the pump and spray tip.
GPM (Gallons Per Minute) - The volume of water available for cleaning.
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.
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.
A lot of low cost pressure washers with no-name pumps on them (or pumps on cheaper name brand machines) have very low life expectancies (Some as low as 35 -100 hours). When buying a pressure washer, make sure you find out the life expectancy of the pump. If the information is unavailable, stay clear because it is very likely that the manufacturer does not want you to know how low of quality it is. Another very important factor to consider is parts availability. KMS Tools was a warranty/service centre for some low-end brands, however, parts availability and unreliability of these machines were so vast that we decided to no longer provide this service. Before buying your machine, ask where you can get parts if you need them. After the sales person tells you, verify what he is saying is accurate by actually contacting the business that was referred. KMS is often referred to by other retailers as a source for parts and repairs for numerous brands that we do not service or repair.
If you are buying a low price machine from a Big Box store, expect it to be a disposable machine that might last you one season.
To prep your pump for winter, flush it with clean water and prime it with anti-freeze. On gas models pull the rope slowly a few times so that the pistons move around to make sure the anti-freeze cycles through the pump.
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.
These 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.
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.
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 Wand: Every pressure washer should come with one. You can change the spray pattern with the different tips 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 wand. 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 wands: A telescoping wand 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 wand. It lets you get into your gutters to clean them out. Be careful though with high pressure machines, if you jamb them into your gutters carelessly the pressure can strip out the caulking in your gutter joints (especially in the corners).
Whirl-a-Ways: 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 my 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.
Hot Water Pressure Washers
Hot Water Pressure washers are commercial machines with built-in water heaters. The cleaning power of the machines is considerably more than a non-heated machine with comparable PSI and GPM because hot water simply cleans more effectively than cold water. Heated water breaks down and removes dirt and grime faster than a normal pressure washer can, reducing the amount of time you need to spend cleaning. These also clean heavier stains (like grease).
Do not feed hot water into a normal pressure water pump that was not designed for it. The heat will damage seals and O-rings.
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.
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.
You can download the buying guide here if you’d like to print it off yourself and keep it for reference.