If you'd like to have a tool around your house that will do everything from gently cleaning off an awning to blasting off loose paint from siding and decks, look no
further than a pressure washer.  Pressure washers can help you with a wide variety of tasks year after year, and they're probably more affordable than you thought - and yes, they even do windows.
A pressure washer is considerably more powerful than a garden hose -- about 25
percent to over 100 percent more, in fact - but they are very easy and, with the proper common-sense precautions, very safe to use.  An electric or gasoline-powered engine is used to run a small, high-efficiency pump.  A garden hose is attached to one side of the pump to supply the water from any exterior faucet, and a high-pressure hose, wand, and spray nozzle are attached to the other side.
Shopping for a pressure washer
As you might expect, what you've paying for with a pressure washer is quality and power of the pump and the engine.  The gasoline engines are typically rated in the five to seven horsepower range, and almost all of them have a simple recoil pull-rope starter.  Electric units, while easier to use and maintain, have a lot less power and are more limited in their uses.
More important than the horsepower of the engine, however, is how powerful the pump is.  Pumps are rated in two ways - PSI (pounds per square inch, a rating of
pressure), and GPM (gallons per minute, a rating of water flow).  Both are important considerations, and the higher each number is, the more powerful the pressure washer will be.
Lighter duty gas units will typically be in the 2100 to 2300 PSI range, and will move around 2.0 to 2.2 GPM of water.  These are best suited for washing cars, patio
furniture, smaller decks and patios, barbeque equipment, and similar tasks.  In this range, expect to pay between $250 and $300.  Moving up from there will be the
medium-duty washers in the 2400 to 2500 PSI range at about 2.5 GPM for around $400 to $500, which will do everything the small units will do, but on a larger scale.  They'll also work well for cleaning siding, and some lighter paint removal.
Heavy-duty, commercial-rated pressure washers can range from 2600 to 3600 PSI or more, and move three GPM and up.  These higher-pressure units will do heavy paint removal, removal of heavy grease and grime from driveways and equipment, pool cleaning and maintenance, and more.  Expect to pay from $700 to $1,000 or more for these bigger units.
The engine and pump are mounted on a metal frame and obviously represent quite a bit of weight, so another consideration is portability.  Some of the lighter-duty models utilize a frame with a handle but no wheels, an inconvenience if you plan to move it around very much.  Better units have wheels - the bigger the unit, the bigger and more rugged the wheels - along with folding handles, on-board storage for nozzles, and quick-connect hose fittings.
Most pressure washers come standard with 15 to 25 feet of hose - the higher-pressure units use larger, heavier hoses - and three or four interchangeable nozzles.  Most units also have a small tube attachment called a soap pickup, which can be placed into a bucket of soap, degreaser, or any of a variety of other chemicals.  With the soap pickup in place, when the trigger is pulled on the wand the pressure of the water will siphon the soap or chemical into the water stream and spray it out of the nozzle as well.
Operation
Operation of a pressure washer is very simple - actually just a matter of attaching the hoses, starting the engine, and pulling the trigger on the wand.  The only adjustment is done through a pressure-regulating knob on the pump, which allows you to regulate the force of the water pressure.
At the end of the wand is a nozzle, which is a brass fitting with a tiny hole in the end to accelerate and direct the stream of water.  Switching nozzles will allow you select the overall spray pattern of the water, from a wider, lower-pressure stream for cleaning to a very narrow, high intensity spray for paint removal or spot degreasing.
Beyond that, operation requires a little bit of practice to get a feel for how close you need to be to the surface being washed, and how fast or slow to move the wand.  For general washing, for example, you would typically utilize a wide-pattern tip that allows you to clean a wide area quickly without risk of damage to paint.  Narrower tips will focus the water in a smaller area at greater pressure - be careful, however, as too hard and narrow a stream can do a lot of damage to your siding in a real hurry - so start with the widest, lowest-pressure nozzle and work up from there.  In addition, always follow all manufacturer's recommendations for safe operation.
Pressure washers are available from most home centers, paint stores, larger discount outlets, and specialized dealers.  For infrequent use, they can also be rented at just about any rental yard.