If an independent power source is needed which is not constrained by the electrical supply then a diesel or petrol engine model is the answer. This type of pressure washer can be more powerful than electric machines and is ideal for off site work. These machines are often mounted in a tubular steel frame for robustness.
Hot water pressure washers are also available with electrically heated boilers which offer limited temperatures. These machines are normally used where using kerosene is not an option. Deciding on which pressure to buy or hire is complex. This relationship between water flow and pressure is important depending on the type of cleaning being carried out. Reading the technical specification of a washer is fine but is the pump of good quality? Is the hose of the correct rating for the machine and is it long enough for your needs?
In a hot water pressure washer the design inlet temperature should not be exceeded as it may affect the seals in the internal machinery. The size of the motor that drives the pump to produce the water pressure. The motor size is normally expressed in Kw for an electric washer and HP for an engine driven version. The motor must be correctly sized to match the pump to ensure optimum performance. On cheaper machines the pump may be smaller than the ideal size meaning it has to work harder to create the required flow and pressure and as a consequence will not last as long.