Pressure washers: The pressure is on

Helping customers clean up the right way

Finding the right pressure washer for the job isn’t as easy as it sounds. If your customers rent an underpowered product, the results will be disappointing. On the other hand, going with an oversized unit adds inconvenience and extra cost, not to mention the possibility of the operator damaging the property.

Education is the best way to help a customer determine the right pressure washer for his or her needs. It takes an understanding of the machine, the application and the cleaning process itself to make a proper selection.

  • Choosing hot or cold. As with any learning process, it’s best to start with the basics. In the case of pressure washers, this means figuring out whether a hot- or cold-water unit is needed.

Cold pressure washers are the most popular option. They’re compact and economical, and they’ll do the trick for a large number of cleaning jobs. Generally, cold-water units are best at washing away dirt and mud. That alone covers a lot of applications, from washing a construction vehicle to cleaning concrete.

Where cold water falls short, however, is removing grease or grime — dirt that is ingrained or clinging to a surface. A cold pressure washer may push these substances around, but it won’t produce a clean surface. For instance, if the machine is used to clean the fifth wheel on a tractor-trailer, it will likely splatter and smear the heavy grease, rather than wash it off.

When dealing with grease, grime and oil, a hot pressure washer is usually a better choice. That’s because hot water actually cuts through grease, loosening it from the surface. Once the bond between the grease and the surface has been broken, it can then be washed away.

Also, remember that the performance of either a hot or cold pressure washer can be enhanced by using cleaning chemicals. There are a variety of detergents available for use with pressure washers and using the right one can help the cleaning process go much more smoothly.

  • Picking a power preference. Both hot and cold pressure washers are available with electric motors or gas-powered engines. This decision is largely based on where the machine will be used. If it will be operated outdoors without adequate electrical sources nearby, then a gas-powered unit is the best bet. Otherwise, many people prefer the cost efficiency, fewer maintenance needs and quieter operation of an electric motor. Keep in mind that many of the higher-powered electric pressure washers require a 230V, three-phase power source, which isn’t readily available in many locations.

If selecting a hot pressure washer, a person also must choose one of three options for heating the water: oil-fired, gas-fired or electric. The most popular choice is oil-fired, which can use diesel, fuel oil or kerosene to heat the water. These units are highly portable, and the fuels are affordable and readily available.

The next option is gas-fired, which means the machine can burn either natural gas or liquid propane (LP) gas. However, this option is typically reserved for stationary pressure washers that are hard-plumbed into the gas system of the building where they are located.

The third option is to use electricity to heat the water. Although convenient and highly portable, these units use high voltage and draw high current. Therefore, these products are only recommended if the operator has easy access to such electrical sources.

  • Check the specs. After deciding on the type of pressure washer, a person must determine what specifications will best meet his or her needs. Pressure, volume and horsepower ratings are often misunderstood, but they play a large role in the performance of a pressure washer.

Start by considering pressure. Simply put, its purpose is to help break the bond between the contaminant and the surface being cleaned. If the pressure is too low, the bond won’t break without extra help from hot water or detergents. If the pressure is higher than what’s needed, the dirt will blow around more and the high-pressure spray may even damage the surface.

With this in mind, it’s best to find a happy medium — a pressure washer that has adequate ratings for the type of use it will experience. For instance, if the user will mostly be washing his vehicles, a 1,500-psi unit may work fine. If washing agricultural, construction or mining equipment, consider using at least 2,000 psi. For industrial jobs, 3,000 psi or more is often required.

Many people assume that pressure is the only important rating of a pressure washer, but that’s not true. Volume, which is stated in gallons per minute (gpm), equally affects cleaning performance. After the pressure has broken the bond between the contaminant and the surface, the contaminant must be washed away. The greater the flow of water, the better the substance rinses off. In fact, professionals rely on high-volume units to complete their cleaning jobs quickly.

Although one might assume that a high-volume pressure washer would only consume large amounts of water, this also is not necessarily the case. The average garden hose dispenses between 6 and 8 gpm, while the average pressure washer puts out 3 to 4 gpm. Therefore, even the highest-rated pressure washers usually offer some type of water savings.

The third factor, horsepower, is useful because it determines how much pressure and volume a pressure washer can produce. For example, a 3,000-psi, 4-gpm unit requires at least an 11-hp gas engine to achieve those outputs. Anything less than 11 hp will deliver less pressure and volume than the pump’s actual rating.

Basic formulas can be used to calculate the minimum horsepower requirements of a machine. Note how electric-powered units use a different equation than gas-powered:

  • Electric motor horsepower requirement: (PSI x GPM)/1,460
  • Gas engine horsepower requirement: (PSI x GPM)/1,100

Another way to look at the pressure and flow ratings is through cleaning units. Factoring in both psi and gpm helps compare the cleaning power of pressure washers. To come up with this number, simply multiply the pressure and volume specifications. For instance, a 3,500-psi, 3.8-gpm machine would have 13,300 cleaning units, while a 3,000-psi, 4.5-gpm unit would have 13,500 cleaning units. In this scenario, the second unit would offer higher performance.

  • Determining durability. Reliability also plays an important role in the pressure washer selection process for equipment rental stores. Before deciding on one, carefully inspect the unit and pay attention to the details. For starters, is the frame constructed of thick steel? Considering the amount of abuse many pressure washers receive, this can make a huge difference in the longevity of a machine in a rental store’s inventory.

Also, check the quality of the engine or electric motor. Is it made by a reputable manufacturer? Does it have adequate horsepower to drive the pump? If the answer to these questions is “yes,” then the operator is more likely to experience satisfying results.

Next, make sure the pump can handle the workload. Ceramic plunger pumps are regarded as the highest quality in the industry and the best ones are designed to run for 2,000 hours or more, as long as they’re well maintained. Compare this to pressure washers intended for occasional homeowner use, which may have a service life of only 100 to 200 hours.

One of the most important components is the unloader valve, which experiences more wear and tear than any other part of the pump. The unloader valve activates every time the spray wand’s trigger is released, allowing water to cycle through the pump, so if it’s not functioning properly, it can lead to significant damage. Therefore, a person should ensure that this component is high quality and easy to replace before selecting a unit.

The guidelines for picking a pressure washer aren’t complicated, but they’re important to understand because your customers will be extremely disappointed if they rent an inadequate unit that does a poor job. They may become even more frustrated if they damage a surface with an oversized pressure washer. In the end, learning these guidelines will be well worth the time as your customers will find their pressure washer rentals to be well worth the money.

Daniel Leiss is president, Jenny Products, Somerset, Pa. For more information, visit