How to choose a hot water pressure washer: pressure and use

A hot water pressure washer makes sense when you have to remove grease, oil and stubborn dirt: workshops, car washes, farming and livestock, industrial kitchens, site machinery. The burner heats the water and the heat dissolves residues that cold water merely moves around. For light dirt (mud, dust, soil) cold water is almost always enough, and is simpler and cheaper to run.

The types

• Hot water pressure washers with burner. Machines with a burner and a fuel tank. They are the largest part of the collection, with Nilfisk models such as the SH AUTO 5M-100/500 DSS and the SH SOLAR 7P-170/1200 and SH SOLAR 8P-180/2000 ranges. The codes contain the pressure and flow figures: check what they mean on the product sheet.
• Skid versions. Mounted on a base to be installed on vehicles or plant, like the Skid Fuego IPC Worldwide.
• Annovi Reverberi pressure washers of the 25, 35, 45, 56, 66 and later series. Models of various sizes, for example the Series 2591 and the Series 3590.
• Water heaters. Units dedicated solely to heating the water.

How to choose by job

The features to look at

• Power supply and frequency. In the collection you find 230 V machines and 400 V three-phase machines, all at 50 Hz. Before ordering, check the socket available: a three-phase machine cannot be connected to a domestic socket.
• Temperature rise (Δt). The data show a heating of about 55 °C: it indicates by how many degrees the burner can raise the temperature of the incoming water.
• Rpm. The product sheets state 2800 rpm.
• Weight and dimensions. They range from about 48 kg to more than 230 kg. The lighter machines are moved by hand, the heaviest stay in a fixed position. Also check the overall size, which in the collection is about 50 × 73 × 92 cm for the most compact models.
• Fuel. The burner has a dedicated tank: check which fuel the machine uses.

Before deciding, write down three things: what you have to wash, how much water you have available and what electrical supply there is at the point of use. With these three pieces of information the choice narrows down at once: the most compact machines in the collection, around 50 kg, can be moved by themselves and are enough for workshops and small businesses; those over 200 kg stay in a fixed position and are for places where washing is a daily job. Also consider who will use the machine: for an inexperienced operator, a model with simple controls and a single working nozzle is better.

Common mistakes

• Choosing hot water for dirt that does not call for it. For soil and mud it costs more and does not clean any better.
• Connecting to a water supply with insufficient flow. The machine must receive enough water, otherwise the pump suffers.
• Not bleeding the air from the gun. This must be done before lighting the burner.
• Switching everything off at once at the end of the job. Switch off the burner first and run cold water through to cool the coil.
• Using any detergent. You need products suited to pressure washers.

Frequently asked questions

When is hot water worthwhile?

When you have to remove grease, oil, dried or encrusted dirt: the heat works together with the pressure. On mud and dust it is not needed.

Do I need a three-phase socket?

It depends on the model: the collection includes 230 V machines and 400 V three-phase machines. Check the code and the product sheet before ordering.

Can the jet be pointed at cables and sockets?

No. It must not be pointed at people, cables or sockets, and the nozzle is kept at a distance from the surface.

What is the difference from cold water?

Cold water is simpler and suited to light dirt; hot water degreases better but requires fuel and more maintenance.

All the machines are in the hot water pressure washers collection: to choose pressure, flow rate and power supply, request a quote or ask the AMES technicians for advice.