Dear Jim: I have an efficient two-story house. I plan to install a central vacuum cleaning system myself to help control dust for my allergies. Will one work in a house such as mine and what features should I consider? – Pam B.

Dear Pam: A central vacuum cleaning system is an excellent choice, particularly for an energy-efficient, airtight house. I installed a central vacuum system in my own two-story house three years ago. It cleans very well and operates so quietly, I can talk on the phone while cleaning.

Some central vacuum cleaning systems exhaust the air outdoors. But most, such as mine, exhaust the clean air through a muffler into the utility room or basement. This eliminates concerns about having an airtight house.

Although central vacuum cleaning systems use a powerful motor or several motors in the central power unit, they still are plugged into a standard electrical outlet. Overall, they may end up using less electricity than a small portable vacuum because they thoroughly clean with less run time.

If you can saw a piece of 2-inch-diameter plastic pipe, a few holes in drywall and run some safe low-voltage wire, you should be able to install a system yourself, even in a two-story house. To access the second floor, the pipe often is run up to the attic first and then down to one or two rooms.

When selecting a central vacuum system, the key items to consider are the cleaning power and the filtration method in the power unit. Don’t be swayed by claims of “peak horsepower” of the motor indicating cleaning power.

The true cleaning power of any vacuum cleaner, central or portable, is the airflow rate (in cubic feet per minute – cfm) and the suction force (inches of water lift). Of these, the airflow probably is most important.

Through an engineering formula, airflow and suction are combined to yield an overall “air watts” power rating. This rating ranges from about 400 to 900 depending on the model. The size of your house, length of pipes, number of elbows, etc., all affect the amount of air watts your system requires.

Select a system that uses a filtration method with several stages. Models with a cyclonic filter spin the dirty air at a high velocity, which causes the dirt to fall into a canister. The exhaust air then flows through a secondary filter. Other models use replaceable filter bags or combinations of the two.

A motorized brush power head is best for cleaning carpet. Some models have a built-in microprocessor with indicator lights to set the height adjustment. Another convenient option is a sweep outlet for kitchens or other hard floors. The vacuum starts when you flip it open. Sweep the dirt to it and it is sucked away.

Write for (instantly download – www.dulley.com) Update Bulletin No. 831 – buyer’s guide of 12 central vacuum manufacturers (55 models) listing filtering methods, air watts, cfm, suction, dust capacity, features, prices and a piping layout guide. Include $3 and a business-size SASE, and send to James Dulley, 6906 Royalgreen Drive., Cincinnati, OH 45244.