QUESTION: How effective are the lightweight portable air conditioners that can be rolled from room to room? I have central air-conditioning, but I need extra cooling in some rooms at times. Are they efficient?
ANSWER: These lightweight portable air conditioners on casters can make economic sense for houses with or without central air-conditioning. They certainly make sense from a comfort standpoint. Some models weigh only 36 pounds and have handles for easier carrying up and down stairs.
Even with central air-conditioning, what house doesn't have a room that is always a little too warm or uncomfortably humid? If you set the thermostat to keep that one room comfortable, the rest of the house gets too cool. This is not only uncomfortable, but it pushes up your electric bills.
People often use a portable unit in the kitchen while cooking. After dinner, they roll it into the living room while watching TV. At bedtime, it goes to the bedroom that is always a little too warm. All portable models plug into a standard 110-volt wall outlet.
Most portable models use small, quiet rotary compressors. As a byproduct of cooling your room, some draw more than four gallons of moisture out of the air every day. The best models have thermostats, multispeed fans and oscillating louvers to distribute the cool air evenly throughout the room.
If you plan to roll one into a bedroom at night, select a model with a time-delay shut-off. You can go to bed while the unit is cooling and have it shut off automatically after you fall asleep, saving electricity.
On most models, a small, flexible clothes-dryer-type duct runs from the back of the unit to a window or door to transfer the heat outdoors. They come with adjustable adapter panels to fit any window or door. The unit can be moved from window to window very quickly.
You empty a small water condensate tray every several days on most models, just as with a typical dehumidifier. One model series, the Pinquino, has a sophisticated design that uses this water to pre-cool the condenser and the air. There is no water to empty and the cooling output is substantial.
The most powerful and quiet design is a mini-split system. A lightweight compressor unit hangs outside the window and is connected with a small hose.
In some houses like mine that stay cool from shade trees but are too humid, using a dehumidifier can increase comfort and help allergy problems and overall cooling efficiency. Small room units help some, but new whole-house models, like the Sahara on casters, dehumidify several times more efficiently.
Write for (or instant download http://www.dulley.com) Update Bulletin No. 935, a buyer's guide to portable air conditioners, room and whole-house dehumidifiers, weights, sizes, features, prices and a cost-to-use chart. Please include $3 and a business-size self-addressed envelope and mail to James Dulley, Los Angeles Times, 6906 Royalgreen Drive, Cincinnati, OH 45244.
Deck Support Posts Need Preparation
Q: I plan to build one of the efficient solar decks that you described several weeks ago. I want to use all cedar. What is the best method to treat the support posts?
A: These attractive solar decks are really energy savers year-round. Cedar is a good choice, but it does require special preparation.
Soak the end (that will be used in the ground) of the cedar post in a preservative like Cuprinol. Put about eight inches of small aggregate in the hole and set the post in. Add another couple of inches of aggregate. Pour in the concrete and be sure the top surface slopes away from the post.
Identical Wall Material Has Different Names
Q: We are designing our dream house and we want it to be efficient. I want to make many of the material decisions. What is the difference between drywall, Sheetrock, gypsum panels, wallboard, etc.?
A: It is a good idea to research and make--or at least be involved in making--the material decisions. Builders are understandably cost-conscious, but you have to live in the house for the next 30 years.
All of the words you mentioned are just different names for the same basic wall material. Sheetrock is a trademark of USG's gypsum wall panels, which use recycled paper and synthetic gypsum, an otherwise disposed-of material.
Letters and questions to James Dulley, a Cincinnati-based engineering consultant, may be sent to James Dulley, Los Angeles Times, 6906 Royalgreen Drive, Cincinnati, OH 45244.