Two machines sit side by side. Both claim 150 bar. Both claim around 12 litres a minute. One costs £400, and one costs £1,400.
On paper they are the same machine. In practice, one of them will be dead inside eighteen months of daily use, and the numbers on the box will not tell you which.
If you are buying a pressure washer that has to earn money, the specifications everyone quotes are the least useful part of the decision. Here is what to look at instead.
Duty cycle is the number nobody prints
Duty cycle is how long a machine can run before it needs to stop and cool. It is the single most important difference between a domestic and a commercial machine, and it very rarely appears on the box.
A consumer machine is designed for perhaps twenty or thirty minutes of use, then a rest. That is fine for a car and a patio on a Sunday.
A commercial machine is designed to run continuously through a working day. Some are built for genuinely continuous duty with no rest at all.
If you are cleaning for six hours, a machine rated for thirty minutes will not last. It does not matter what its bar rating says, because bar describes what it can do for a moment and duty cycle describes what it can do for a living.
Motor speed tells you more than pressure
This is the single best proxy for build quality, and it is usually findable.
A pressure washer pump is driven by an electric motor. That motor typically runs at either around 2,800 rpm or around 1,400 rpm.
2,800 rpm machines get their output from spinning fast. The motor and pump are smaller, lighter and cheaper. Everything wears roughly twice as quickly.
1,400 rpm machines get the same output from a physically larger, slower-turning pump. Slower means cooler, quieter and dramatically longer-lived.
Almost every serious commercial machine runs at the lower speed. If a machine's motor speed is not published, that is usually an answer in itself.
What actually matters, in order
Duty cycle. Match it to your longest working day, not your average one.
- Motor speed. Lower is better, and it is the clearest quality signal available.
- Pump construction. Brass head, ceramic-coated plungers, serviceable seals. See our piece on what makes a pump last.
- Flow rate, ahead of pressure. This is the one most buyers get backwards. Pressure lifts dirt. Flow carries it away. For large areas, a machine with more litres per minute cleans faster than a machine with more bar. Chasing bar alone gets you a machine that blasts a small spot furiously and cleans a car park slowly.
- Serviceability and parts. Can you get a seal kit in five years, and will somebody fit it?
- Hot or cold. Covered below.
- Electrical supply. A 240V single-phase supply limits what you can run. Larger machines need three-phase, and finding that out after delivery is an expensive afternoon.
Hot water: when it earns its cost
Hot water machines cost considerably more, and for a lot of buyers they are unnecessary. They earn their place in one specific situation: anything greasy, oily or fatty.
Cold water at high pressure pushes grease around. Hot water dissolves it. If you clean kitchen extraction, food production areas, engine bays, workshop floors, plant machinery or agricultural equipment, hot water is not a luxury; it roughly halves the time and cuts chemical use.
If you clean masonry, paving, vehicles' exteriors, fencing and general grime, cold water is fine, and the extra cost is wasted.
Matching the machine to the trade
Mobile valeting and detailing. Compact, transportable, cold water is usually enough. Weight and footprint matter as much as output because it lives in a van.
Cleaning contractors doing exterior surfaces. Prioritise flow rate over pressure, and add a rotary surface cleaner. Cold water in most cases.
Workshops, garages and plant maintenance. Hot water pays for itself quickly here. Grease is the entire job.
Agriculture. Long hours, hard water, corrosive environments. Duty cycle and serviceability outrank everything, and hot water helps with organic soiling.
Food production and catering. Hot water, and check what your environment requires in terms of finish and hygiene compliance.
Facilities and grounds teams. Usually cold water with a good surface cleaner, chosen for durability because it gets shared between users.
The cost that decides it
Work it out over five years, not at the till.
Take the purchase price. Add servicing, which for a commercial machine is a modest annual figure. Add expected downtime, priced at what a lost day actually costs you in labour and missed work.
Then compare that against replacing a cheaper machine every eighteen months to two years, which is what daily commercial use does to a consumer machine, plus the days lost each time one fails mid-job.
The cheaper machine usually loses that comparison somewhere in year two, and the gap widens every year after.
Frequently asked questions
What is the best commercial pressure washer for a small business?
The right answer depends on hours of use and whether you need hot water, not on a single model. Match the duty cycle to your longest working day, choose a slower 1,400 rpm motor over a 2,800 rpm one, prioritise flow rate over pressure for large areas, and confirm parts availability before buying.
What is the difference between a domestic and a commercial pressure washer?
Duty cycle and pump construction. A domestic machine is designed for short sessions with rests between, using a fast-spinning motor and a lighter pump. A commercial machine is built to run through a working day, usually with a slower motor, a brass pump head and serviceable components. Pressure ratings are often similar, which is why they mislead.
Is higher pressure always better?
No. Pressure lifts dirt; flow carries it away. For large surfaces, more litres per minute cleans faster than more bar. Excessive pressure also damages soft substrates such as render, timber and some paving. Match pressure to the surface and choose flow for area.
Do I need a hot water pressure washer?
Only if you deal with grease, oil or fat. Hot water dissolves them where cold water simply moves them around, so it is worth the extra cost for workshops, kitchens, food production, plant and agriculture. For masonry, paving, fencing and vehicle exteriors, cold water is sufficient.
How long should a commercial pressure washer last?
A properly built commercial machine, serviced on schedule and fed clean water, should give ten to twenty years of regular use. A consumer machine put on daily commercial duty typically lasts eighteen months to two years. The difference is duty cycle and whether the pump can be rebuilt.
The bottom line
Ignore the headline numbers. Ask how long it can run, how fast the motor turns, whether the pump can be rebuilt, and whether you need heat.
Answer those four and the shortlist writes itself.
Kränzle UK is the UK's largest Kränzle stockist, supplying cold and hot water machines built for continuous commercial duty, with spares and servicing in-house. Tell us your trade and your working day, and we will tell you which machine fits, and which one is more than you need.