If you are going to be cleaning a concrete surface, and you have to do this on a regular basis, your choice of pressure washer will be extremely important. There are some essential factors you should include in your search process, with gas vs. electric as a primary element. Once you’ve decided between these two options, you’ll want to focus on size – not the mass of the body itself but the ratings for pounds per square inch and gallons per minute. Look for these to be indicated by PSI and GPM.
Be sure of the tasks you’re going to perform — what surfaces you’re going to clean, and how often you’ll be doing these jobs. It will be easier to make your decision if you narrow your choices down to three categories – residential, commercial, and professional. These are not set in stone, of course, but the three general groups will help you make the right choice for your purposes. As with any job, around home or in a business, you should be sure of the job you’re trying to complete, so have a goal in mind.
Electric or Gas?
In general terms, you’ll get more heavy-duty results from a gas-powered pressure washer than from an electric unit, but the final factor will be the overall size and rating of the units. An electric washer in the 1300 PSI to 2000 PSI range will be fine for residential tasks such as washing your car, cleaning a small patio or deck, and so on. These units will be smaller in size, range in weight from about 15 to around 30 pounds, and will have a high-pressure hose. The most-popular units in this category come with four or five tips for various tasks.
If you choose a gas-powered unit with a 2000 PSI to 3100 PSI rating, and a GPM of 2 or slightly above, you’ll be taking a step up to cleaning larger decks, fences, home siding, larger vehicles, etc. Key features should include overhead-valve engine, pump with axial-cam design, brass or aluminum head for higher pressures, professional-grade steel wand, and a variety of tips for different spray jobs. What you need to be aware of when making this choice is the price for units of equal power and performance.
Take your cleaning to the next level with a professional-grade, gas-engine pressure washer delivering 3200 PSI to 4200 PSI and in the range of 3 GPM to 4 GPM. This is what you need for stripping paint, removing graffiti, and cleaning on the construction site. These washers will generally have commercial-duty pumps, welded-steel frames, industrial-strength axles, braided hose for high-pressure use, pneumatic tires, and a professional-grade spray wand made of steel. You will also benefit from the quick-connect feature on the coupling, and you’ll get a range of spray tips.
The performance of pressure washers is usually measured by the pressure they deliver and the volume of liquid they produce, but there is another element you should take into consideration. Some equipment in the light-duty/medium-duty categories produce warm water. Many of the products you’ll look at in medium-to-high range also give you the option of cold or hot water. Hot water is the choice when you have to remove grime or grease on a regular basis, because the higher temperature helps pull the dirt and other particles out of the concrete. Cold water will usually rearrange the dirt but won’t give you the deep clean you may be after.
If, however, you’re cleaning mud and loose dirt from concrete, you could get a satisfactory performance with cold water. It’s interesting to note that because hot water cuts through grease and helps loosens this tough material from the surface, you will get best results outdoors, in cool/cold temperatures with a hot-water pressure washer.
But, don’t heat the water too high. In fact, something a bit warm to the touch (104°F, for example) should produce noticeable results. This is very important when you’re cleaning masonry and there is risk of loosening mortar or damaging the surface of brick or stone. Another factor to consider when choosing between hot and cold, is the location in which it will be used most often. You’ll need a larger electric unit to do the same tasks as a gas-powered unit, so you might even have to provide 230-volt service so the electrical unit performs as it should.
When you’re doing more than simply spraying the loose dirt off your exterior walls before painting, or cleaning the patio/deck surface of loose material, you’ll benefit from digging into the details in two areas: nozzles and horsepower. Take the last of these factors first – horsepower. Most people understand this is the element that contributes to how fast a car accelerates and so on. But horsepower also determines the volume of water and the pressure you get from your power washer.
If you buy a unit with a 10-horsepower gas engine (or higher) you’ll be using about 4 gallons per minute (GPM) at 3,000 pounds per square inch (PSI). This is where the second factor comes in – nozzle design. For example, this level of power might damage delicate masonry if you forced it onto the surface directly. But with a 15-40 degree fan nozzle, you should get the performance you need for cleaning masonry.
Concentrated streams from tips of less than 15 degrees or the laser tip, is what you might use for concrete and stone surfaces that won’t be damaged by the power of the water. Nozzles from the leading manufacturers will be color coded so you can more easily select the spray pattern. The range is from white (40 degrees) to red (0 degrees). Fifteen-degree tips will be yellow and a 25-degree tip will be green.
It’s always best to test your nozzle and spray pattern in an area you won’t be concerned about, to make sure you’re getting the results you need. This is also the time to judge effective distance from the surface you’re cleaning, as well as the angle that produces best results.