Home Exterior.
Power Pressure Washers
Pressure washers use electric or gasoline motors to power a high pressure water pump. A common garden hose connection keeps the pump supplied with water. The high pressure water is released using a "wand" that usually has adjustable or replaceable tips. Some washers have a suction hose that will draw in a cleaning solvent and add it to the stream of high pressure water.
Both electric and gasoline power require a garden hose connection and both come in a variety of power ratings (PSI) and costs.
The choice between electric or gas depends on several considerations:
Electric units tend to be less powerful than gasoline powered.
Electric units are usually smaller, an advantage for storage.
Electric units require a grounded power cord. An additional line to drag around. If anyone is making a battery powered electric power washer...that will be news. The power consumption is higher than what one could expect from a battery, but technology improves almost every day.
Gas units avoid the line to drag around but tend to be heavier, many use wheels.
Power Pressure Washers are rated by pounds per square inch (PSI) and gallons per minute (GPM). The PSI is the amount of force available to do work. The higher the pressure the more likely you will be able to remove whatever it is you want to wash off. Of course with too much power you may remove too much, like the paint off your deck or the trim on your house. It is possible to damage wood and synthetic deck materials like Trex® if not careful. A high power unit tends to clean larger areas faster. This is in part because the end of the wand can be farther from the work and make a wider pattern.
Most washers have interchangable tips. Select the tip and spray pattern right for the job at hand. If used carelessly and the wand is too close or comes in contact with wood it can tear the wood fibers.
So, get a powerful unit if you have a lot of area to cover and focus the wand at a safe and appropriate distance.
Matching the correct power washer to the jobs you have in mind can be difficult and no one can advise you on EXACTLY what will work for you. So, go to your nearest tool rental center and see what they have. Rent a big or small unit for your big or small job. If it works poorly (or too well) go back and exchange it for a different model. When you find what's right, you can buy one like it. Or if you don't use it often, keep on renting.