Q. Our air-conditioning bills were very high last year and we are looking for a way to cut them down. What about a whole-house fan?
A. Whole-house fans work best in areas where outdoor air is cool enough for comfort at night if brought indoors. Night temperatures of 75 degrees or less are preferable. A whole-house fan is significantly cheaper to operate than an air-conditioner, and in some homes serves as a backup – the fan is shut off and an air-conditioner is used in hot weather.
The object of a whole-house fan is to pump the cool outside air into the building and expel existing hot air. During the day, when temperatures warm up, windows and drapes are closed to keep the cool air inside. The fan is usually installed in the floor of an attic, although some fans will fit into a window, wall or some other special location.
The most-favored location is a ceiling (attic floor) over a central hallway. The fan pulls in air through partially open windows and expels hot air through vents in the attic; vents are often installed in the gables, but soffit and roof vents are sometimes also used. The fan sits on a louvered panel; the louvers open automatically when the fan is running and close when it shuts off.
Some fans have variable speeds and thermostatic control. Whole-house fans, sometimes called “the poor man’s air conditioners,” have some disadvantages.
Windows usually need to be left open only 4 to 6 inches, but that can pose a security risk. Some homeowners have overcome the security problem, finding ways to lock the partially open windows so they cannot be opened far enough to admit an intruder. Use a search engine and the words Locks for Partially Open Windows to view some of the solutions.
The fans can also be noisy. A large fan opening in the attic floor poses a heat-loss problem in winter. Some owners cover the fan with pieces of blanket-type fiberglass insulation in winter, others have bought or made special covers that help seal the fan in winter.
Still another disadvantage is that a fan can cause backdrafting, meaning that flame-type appliances such as gas water heaters and driers must be properly vented to the outside and their compartments kept closed when the fan is running; otherwise, carbon-monoxide gas might be drawn into the living area.
I have installed and used whole-house fans in several houses where I lived, and I found that the energy-saving advantage overcame the disadvantages.
Q. What is the best way to remove oil stains from a concrete driveway?
A. There are many ways to treat oil stains on concrete and asphalt, and readers of this column have submitted some of their favorites over the years.
One remedy that keeps getting mentioned, and was recommended by a couple of service-station operators who deal with oil stains regularly, is Oil Eater. This is a degreasing solvent that is sprayed on the stain, scrubbed, allowed to work for a given time, then is flushed off with a stream of water from a hose. Oil Eater is sold at some discount stores, such as Costco, and on the Internet at Amazon.com and other sites. A gallon costs less than $15 and smaller spray bottles are also available.
Like most stains, oil is much easier to remove if treated quickly. If a special cleaner isn’t available, try to absorb some of the fresh stain by sprinkling on a coating of absorbent material such as cat litter (not the clumping kind), sawdust, sand, talcum powder, or even a pad of white paper towels.
Leave the absorbent in place for several hours if possible, then sweep it up and apply a fresh layer of absorbent. It is often possible to remove most of a stain with this treatment if quick action is taken and, in any case, the remaining stain will be easier to clean.
It should go without saying that oil leaks in vehicles should be checked and repaired immediately. Leaks are especially common after oil changes; it pays to temporarily slide a piece of heavy cardboard or an oil drip pan under the engine area to catch any stray oil. Other common causes of drips are a loose oil drain plug, loose filter or oil-pan bolts.