Pressure Washers: A Buyer's Guide

Published : 11/14/2017 14:16:31
Categories : Harrison Hire & Sales Posts

If you need impartial advice on buying a pressure washer, also known as High Pressure Cleaners, then read on.... We’ve been supplying them since the 1970’s when our owner, John Harrison imported his first batch from Denmark. As independent specialists in industrial cleaning equipment we have provided a guide on the best machine to suit different types of businesses and range of industries.

Please note that our focus is on business and industrial users, so we won’t be looking at domestic machines in this article. Whilst we are on the subject, unless you need a pressure washer for a very short period of time for a specific job, we wouldn’t recommend a machine intended for the domestic market to be used in a commercial or industrial setting. Components such as the pump are usually manufactured from plastic to keep costs down and so have a limited life span. Industrial machines tend to be built with brass pumps and ceramic pistons, and are intended to be more durable.

There are quite a few factors that you’ll need to take into consideration before you decide. There are portable and stationery versions, hot and cold water models and a variety of power options. It’s also worth knowing the difference between flow and pressure.

Hot or Cold Water?

Cold water high pressure cleaners will do a good job on mud and other everyday dirt, but where there is grease or oil, then hot water is a far better option. You wouldn’t get a very good result washing greasy plates in cold water, and pressure washers are the same. Hot water has the ability to cut through oil more effectively. Many models also have an optional detergent facility – these are available on both hot and cold machines; there are different systems of detergent delivery too!  Some people refer to hot pressure washers as “Steam Cleaners”. Some pressure washers have the facility to deliver water that is so hot that it produces steam. Recent developments with dry steam cleaners have caused some confusion. The two machines are different. A steam generator works by heating water to a temperature that will turn water to vapour, which has the power to sterilise, whereas a hot water high pressure cleaner creates extremely hot water (up to around 150 degrees) that turns to steam when it comes out of the nozzle (when the atmosphere is 1 bar).


What Type of Power?

Consider where you will be using the pressure washer. If you plan to run your equipment in a remote location or an area with no power supply then you will need to find a model that works independently of main electricity. Diesel or petrol are good options.

In food production areas, the exhaust fumes from a diesel or petrol machine would cause hygiene issues so electrically heated versions are available.

Construction sites, and other areas where equipment is required to be 110v, whereas some industrial units, farms and factories operate on a 415v supply. For many of our customers, without specific requirements, a 240v power supply is adequate.

We often supply PTO machines to agricultural users - these use the PTO shaft of a tractor to provide power. You can connect 2 lances and so half the time it takes to do a job. 

A further option is a trailer mounted pressure washer. These have their own tank - very often our customers who have no power supply will not have access to water either, and so are perfect for use in these environments.


Pressure Vs Flow

We frequently are asked by customers for pressure washers with the highest pressure available. Consider what the equipment will be used for and choose a machine to suit your application. Pressure is measured in bar, although you may also see the term PSI (pounds per square inch), which is the imperial measurement used in the USA. Flow is measured in Litres Per Minute (LPM).

Higher pressure will provide a better cleaning action whereas a higher flow is preferable for rinsing. A lower flow rate on a machine means that it will take longer for dirt to be washed away. If you wanted to remove graffiti, for example, a machine with a higher bar would be more effective at removing paint than a lower bar machine. However, if you wanted to clean out animal housing coated with mud then the user would benefit from a good flow rate too.    

The Knowhow of Hoses

Sometimes a pressure washer needs to be sited a long way from a water or power supply, and so extension hoses are required. It is usually better to move the pressure washer closer to the required location and use a longer water inlet hose than use a longer outlet hose. There are some occasions when this is unavoidable – for example, when cleaning the façade of a building it wouldn’t be practical to get a pressure washer up scaffolding! Also, look at buying multiple lengths of hose as opposed to one long hose. It is considered dangerous to repair high pressure hoses, so if a section of 20 metre hose gets damaged it will need to be replaced, whereas you could replace the damaged section of 2 connected 10 metre hoses. The water pressure on long extension hoses only decreases a fractional amount as the pressure supplied by the washer is already quite high. You may only lose 5 bar/100 metres which is hardly noticeable. If this is an issue then fixed pipework that is specifically designed to reduce pressure drops is worth considering.

Specialist hoses can be bought for applications such as drain cleaning – these are narrower and have smaller connectors which are less likely to catch in sewers etc. 

No Butts?

Yes, water butts, IBC’s or pond water can be used with some machines if they are set up to use a suction hose although a hot pressure washer may need to be adjusted to suit this application. A filter is also needed to prevent sand particles from damaging the pump. A machine that is quoted as having a high flow rate will only be as good as the water pressure that feeds it. Poor water pressure = poor water flow. Continually running short of water will put strain on the pump, cause cavitation and will effectively reduce its lifespan.


What’s Goes on the End of the Hose?

Most pressure washers have some type of gun or trigger to start and stop the flow of water at the end of the hose. They can be fitted with either a fixed or swivel fitting. Note that releasing the trigger will not switch your machine off at the base unless it has an automatic stop function, so if you are carrying out work where you need to stop and start the machine frequently this feature is a good idea. There is usually a lance attached to the trigger; this is also known as a Jet Pipe. They come in different lengths and angles to suit the application. If you are working in a compact space then a short lance will be better. An angled lance might be beneficial for cleaning the underneath of vehicles.


Nozzles are not all the same!

It is not possible to increase the pressure of a machine by using a smaller nozzle, but you can reduce the pressure by fitting a nozzle with a larger hole. Ensure you use the correct nozzle for your machine as it is possible to damage the pump by fitting one that is too small. Nozzles come in various angles too or widths. A more flexible option is a triple jet one that adapts from a high-pressure pencil jet (0°), high-pressure fan jet (25°) or low-pressure fan jet (40°). When you need a powerful cleaning action then consider an oscillating nozzle. These are often called Turbo Nozzles, or Dirt Blasters. A pencil jet rotates at high speed to cover a larger area effectively. These also help avoid the tell-tale squiggles on your floors, walls or fence!



There are many occasions when pre-treating an area with chemical is the preferred option. An example is car washing – manually spraying car shampoo onto a dry car helps break down the dirt before you get the pressure washer out. However, as we alluded to earlier, there are different methods of applying detergent: manually, via a foam injector or simply at high pressure. If you use too much chemical then most of it goes down the drain without touching the dirt. Using a foaming detergent means that you use less as it sticks to the surface being cleaned, giving it residence time and a chance to act on the dirt/bacteria.  

Whichever you use, ensure that you read the instructions on the detergent bottle! More chemical doesn’t necessarily mean a better cleaning action. In fact, you could end up with a sticky residue that’s hard to remove, and you are wasting money and possibly damaging the environment too. 

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