The workings are relatively simple: a motor drives the pump to force the water through the hose and lance at high pressure. There are electric models that plug into a normal socket, but there are also petrol and diesel models, if portability is a priority.
After power source, the main differences between models concern motor size, water flow and pump pressure. Higher-pressure washers are likely to give a better cleaning performance, while higher flow rates give a better rinsing action. Pressure relates to the force needed to break the bond between the dirt and the surface. Because you are looking to clean items as diverse as vans and glasshouses, you need to choose a washer with care. A washer with too high a pressure will literally leave you with broken glass — I have even seen a pressure washer used to carve initials into timber decking.
To wash vehicles, a washer with a relatively low pressure of 1,000-1,3000psi will be ample. For decking, around 1,500-2,000psi will suffice. Removing moss and algae from a patio will require greater pressure, say 2,400-2,600psi. In your situation, a washer with variable pressure is probably best, allowing the pressure to be set according to the task.
The frequency and amount of use expected will determine whether you should choose a top-of-the-range domestic washer or an industrial machine. If you plan to use the washer for more than two hours a week — at least 100 hours a year — then an industrial washer is probably best, because the life expectancy of the components is higher; otherwise, a top-end domestic will suffice.
You also have to decide whether to use cold or hot water. The majority of domestic pressure washers use cold water. The advantage of hot water is that it tends to be more efficient at cleaning oil and grease and is therefore useful for vehicles and kit, but these are much more expensive. Stihl offers a range of cold water units costing from £160.85 ex VAT for a basic model to £599 ex VAT for a professional unit. It also supplies the RE551 Plus hot water cleaner. It costs £1,785 ex VAT. That’s the kind of price difference we are talking about.
Looking beyond the pressure washer, you need to pay attention to accessories and detergent. Most models are offered with a range of accessories — often optional — that include different nozzles, blasters and brushes.
Pressure washers, like other power tools, must be used correctly and with care. The high pressure involved means these units are capable of causing serious injury — they can literally peel skin. You need to wear proper eye, face and hand protection when operating a pressure washer. Strong, waterproof clothing is a good idea. Non-slip footwear is a must. If you opt for an electric pressure washer, be aware of the risk of shocks. Always read and follow the instructions in the user manual.
One thing is for sure, when you start using your pressure washer you will wonder how you ever managed without it. You’ll soon be using it to clean outdoor furniture, statuary and pathways — even the drains. You will also find there is a saving in water over normal hosepipe methods.