QUESTION: I am considering installing a whole house fan to use in the evening instead of my air conditioner. Will using one really save much electricity overall? What are the best design and features to get?
ANSWER: Running a whole house fan uses much less electricity than a central air conditioner. Depending on the weather and the number of cooler evenings, the overall electricity savings often range from 25% to 50%.
Many people prefer operating a whole house fan in the evening in order to get some fresh air into the house. With air-conditioning alone, the air in some newer, efficient homes gets stale and can actually become unhealthy.
Whole house fans cool the house and improve comfort in three ways. First, during times when the outdoor temperature is cooler (usually in the evening), drawing in fresh air cools down your house.
Second, the breeze created throughout the house makes you feel cooler. Third, since the air is exhausted into the attic, the attic temperature is lowered significantly. A roof can reach 150 degrees in the afternoon. This heat is stored in the attic material and radiates down well into the evening.
Although all whole house fans look similar, there are major differences among them. The type of controls effects comfort and convenience. Solid-state true variable speed controls and 12-hour timers are a plus.
Check sound-deadening features. The motor should be mounted in rubber grommets to be vibration-isolated from the frame. A hard rubber fan hub also reduces noise levels. A sound-absorbing shroud, made of special chemically treated materials, reduces the noise from the air flow.
The two basic designs of whole house fans are direct drive and belt drive. Direct-drive fans have the fan blade attached directly to the motor. The motor is mounted in the center of the fan opening.
Direct-drive fans work well in small to medium-size houses. Many fit perfectly between the joints without any cutting for simple installation.
For a larger house and for more quiet operation, a belt-drive design is best. By using pulleys with the motor offset on the fan corner, the fan blades turn slower. This reduces noise and allows for a steeper blade pitch. Air flow rates are as high as 8,800 cubic feet per minute (cfm).
For those who close bedroom doors for security or privacy, install a new mini, one-room fan. It is only 14 inches in diameter and the outlet duct is one foot high. This allows you to pack attic insulation high around it.
Write for Update Bulletin No. 880 showing a buyer's guide of 20 whole house fans listing drive types, sizes, cfm air flow capacities, comfort features, installation instructions and charts of recommended fan sizes and attic exhaust vent areas. Please include $2 and a business-size SASE and mail to James Dulley, Los Angeles Times, 6906 Royalgreen Drive, Cincinnati, OH 45244.
Lower Temperature in Freezer May Cost a Bit
Q: I have a fairly large side-by-side refrigerator/freezer. I tend to buy a lot of food on sale. To make the frozen foods last longer, I plan to set my freezer temperature lower. Will this use much more electricity?
A: Lowering the freezer temperature by 5 degrees can increase the electricity usage by about 20%. This can amount to more than 130 extra kilowatt-hours of electricity used each year.
You should set your freezer temperature to the manufacturer's or your local health department's recommendation. First, check it with a good outdoor thermometer. The refrigerator temperature dial may not be accurate.
How to Match Texture of Damaged Ceiling
Q: I installed an efficient electric radiant heater on a bedroom ceiling. In order to install the wiring, I had to damage the texturing on the ceiling. How can I repair and match the old texture?
A: Since every texture job is different, with each drywall contractor demonstrating his artistic talents, it will probably be difficult to match.
If you really want to match it, contact an experienced, often expensive, plasterer. It may be easier to apply a skim coat of drywall compound over the entire ceiling to hide the old texture. This allows you to redo the entire ceiling with a new texture and let the next owner try to match it.
Letters and questions to Dulley, a Cincinnati-based engineering consultant, may be sent to James Dulley, Los Angeles Times, 6906 Royalgreen Drive, Cincinnati, OH 45244.