Here's are some quick tips to help you buy the right carpet cleaning appliance, and get the most from it once you get it home.

1. The more tanks, the better. A decent-quality extractor will have at least two separate holding compartments, one for the fresh cleaning solution, and a second for the grey water coming off the just-scrubbed carpet. Look for a machine with a capacity of at least one gallon (about four litres) per tank; smaller tanks will have you dumping-and-refilling with annoying frequency. A few top-of-the-line machines use a three-tank system: One for the dirty water, one for plain water, and a third for undiluted detergent straight out of the bottle. The machine will do the mixing for you, adding the detergent to the water as it's on its way to the sprayer nozzles. This obviously saves you a bit of effort, but the real advantage is that it adds a "rinse" function to the carpet cleaning process. By making an extra pass spraying only plain water (no detergent added) you can better eliminate any residual traces of shampoo from the fibres, leaving your carpet feeling softer and more natural when it's dry.

2. A solution heater is a plus. In general, the hotter the detergent mixture, the better it will do its job. The holding tanks on most extraction cleaners are uninsulated and will allow hot solutions to cool rapidly unless the machine has an internal electric heating element. Beware, though, of marketing doublespeak, as references to heat don't necessarily indicate the presence of an actual warming element for the solution. One well-known brand claims its extractors have 'heated cleaning' just because they blow warm air onto the carpet!

3. Size matters. Widths -- and heights -- of the cleaning heads on carpet machines vary quite a bit. While a wider head will help you cover large areas faster, it may be impossible to use in tight spaces. A tall head assembly could be tough to work under the sofa if you're spot-cleaning and don't want to start moving furniture.

4. Think ergonomics. Don't underestimate the importance of this. Spend a few minutes pushing, pulling, and lifting the display machine in the store before you cart one home. Do the height and design of the handle work for you? Will you have trouble lugging the unit up and down the stairs? (Don't forget, it will probably weigh 8-10 pounds more when it's full of solution.)

5. Look for active (mechanized) brushes that can be removed for cleaning. Choose a machine with revolving, rotating, or oscillating scrubber brushes. Low-end cleaners often have stationary brushes that won't do much unless you are willing to add a lot of extra elbow-grease (and I do mean a lot.) Ideally, you want a brush assembly that can be popped off for cleaning, as it's much easier to rinse it under the tap than to have to pick debris from the bristles while crouched down on the floor (an added bonus is that you won't need to pay for installation labor when the brushes need replacement.)

6. Check the price and availability of the recommended detergent. If you can't find the manufacturer's approved detergent at your local supermarket -- or at least on the shelves of the store that's selling the machine -- it may be a red flag that the product is unpopular, unreasonably priced or difficult to obtain. It's also a good idea to avoid generics and substitutes, as their effectiveness can be hit-or-miss, and some produce mountains of (very unnecessary) foam that require a lot of extra work to vacuum up. There are even some products formulated with oils that will actually make your carpet get dirty again faster! On top of all that, evidence that you've used a detergent not approved by the extractor manufacturer may void the warranty, even if your machine fails for an unrelated reason.

7. Find out if parts and warranty service are available in your area. Some manufacturers may require you to ship a defective unit at your own expense to their central warranty depot, which could easily cost you $50 or more. Before you buy, check the manufacturer's website or your local phone directory for authorized service centers, then call the nearest one and ask if they are actually able to do warranty work on the particular model you plan to purchase. While you're at it, ask about availability and pricing on common, non-warranty replacement parts, such as the brush heads.

8. Read the instructions! Consumer-opinion websites are overflowing with angry rants from purchasers who couldn't get their steam-extraction cleaners to work properly -- but it's evident from most of the comments that they failed to follow the manufacturer's directions. While many consumer products will let you pretty much skip the instructions, household carpet extractors require attention to the little details, so the owner's manual for your new machine should be considered a cover-to-cover must-read.

9. Fill your solution tank with the hottest tap-water available. This is particularly important if your machine lacks a built-in solution heater. DON'T, however, heat water to boiling in a kettle or on the stove and then pour it directly into the tank unless the manufacturer's instructions specifically recommend it, as you may inadvertently damage soft plastic tubes, valves and seals inside the machine.

10. Work in small areas at your convenience. Instead of dreading carpet-cleaning day and all the shuffling of furniture it used to entail, revel in your newfound freedom and do just one room -- or part of a room -- whenever the mood strikes you or you have a half-hour to spare. Remember: you're no longer in a race to get the machine back to the supermarket before the clock rolls over on another rental day.

11. Slow and steady does it. Don't rush the back-and-forth movement of the cleaner across your carpet, and go over each section repeatedly. The more time your machine spends on each section in vacuum-only mode (not spraying more solution) the better a scrubbing the fibres will get, and the more moisture you will be able to pull back out of your carpet.

12. Don't expect 100% liquid recovery. No matter how thorough you are your machine will never be able to pick up all the solution it sprays onto your carpet. The actual amount recovered will vary with many factors including the machine's suction power, type of carpeting, room temperature and humidity, and how fast you go over each section, but as a rule-of-thumb if you pick up two-thirds of the liquid you put down, you're doing very well. If, on the other hand, you're recovering less than one-third, you should check all the filters and hoses for blockage, and try increasing the time you spend working on each section of carpet.

13. Keep the machine clean. Your extractor needs its own routine cleaning to maximize its lifespan and efficiency. After each use, remove the tanks and rinse them out thoroughly with clear water, then allow them to air-dry completely before reinstalling them on the machine. The shower or tub is a great place to rinse out the accessory hose before hanging it up to drip-dry. And be sure to re-check any screens and filters for lint or dirt. After you've completed a tour-of-duty through the entire house give your machine a more thorough cleaning, giving extra attention to the machine's brushes and suction-head.

14. Keep the weight off the brushes. Nothing will ruin the effectiveness of the bristles faster than having the weight of the machine bearing down on them day after day after day. Whenever the machine is not in use, remove the brush head assembly if possible, and store it with the bristles facing up (or out, if you hang it on the wall.) If the assembly is not easily removable, store the machine tipped backwards so the bristles are completely out of contact with the floor.

15. When it goes, it goes in the trash. Apart from replacing the brushes (which are basically a consumable) it probably won't pay to have a malfunctioning cleaner fixed, unless it's a very minor issue or is going to be covered by a manufacturer's warranty. Parts and labor at posted shop rates can easily exceed the cost of a new machine.