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HOME JULY 2019 6 Dear Jim: I need to replace my noisy, old central air conditioner with a more effi- cient one. I want steady room temperature, humidity control and cleaner air. What sys- tem types do you recommend? — Arvin J. Dear Arvin: At best, your old central air conditioner probably has a SEER (seasonal energy efficiency ratio) of 10. By replacing it with the most efficient new system with a SEER above 25, your electric bills savings can be $2,500 over just five years. These new systems also provide the most constant room temperatures and precise humidity control. Controlling the indoor humidity level is as important for overall comfort as keeping the house cool enough. Humidity control also impacts indoor air quality, especially for people with mold spore and dust mite allergies. Consider replacing your old central air conditioner with a heat pump model instead. It is basically the same as a central air conditioner except it has a reversing valve to also produce heat. During mild fall and spring weather, it heats at a lower cost than running a furnace. During colder weather, its efficiency drops and the fur- nace takes over. Some companies call this a hybrid system. Your three basic options are fully vari- able, two-level and single-level cooling out- put models. Since you are seeking high effi- ciency, steady room temperatures, humidi- ty control, less noise and cleaner indoor air, a variable-output model is your best choice. It also is the most expensive system so have your contractor do a payback analysis first. Variable cooling models use variable- speed rotary compressors which are often called "inverter technology." They continu- ally vary the cooling output to the instanta- neous cooling needs of your house. The cooling level varies in 1-percent increments from about 35 percent to maximum output. In early morning when cooling needs are low, the compressor slows down to about one-third of its maximum output. At this slower speed, it runs longer and more effi- ciently. These longer efficient run cycles maintain room temperatures within just one-half degree of the thermostat setting. These systems use a matching variable- speed blower. At the lower compressor speed, the indoor blower and outdoor con- denser fans also run slower making the entire system, indoors and outdoors, much quieter than single-level models. When you set the desired humidity level on the thermostat, the blower speed auto- matically varies to control humidity. It can continue to dehumidify even when the room air is already cool enough. This elim- inates that cool, but muggy feeling which may occur with a single-level system, par- ticularly one that is oversized for your house. The next step down in comfort, efficiency (SEER in the 20 range) and initial cost is a two-level cooling system. This type of sys- tem runs at the more efficient low-output level the majority of the time. On hot after- noons or when you want quick cooling, it switches to the high-output level. Single-level output models with a single- speed blower speed are the least expensive to install. Since they have only one cooling output level, you can expect a room temper- ature swing of about two to three degrees between run cycles. Dear Jim: I recently had a house built and the exterior foundation foam insula- tion is exposed to the weather. Should I cover it with something to protect it? ˆ Dear Cathy: The weather should not harm the extruded polystyrene insulation, but the ultraviolet rays from the sun can degrade it. Exposed foundation insulation also looks bad. The insulation can be covered with panels such as cement board, vinyl, or pressure-treated lumber. There also are several brush-on foundation paint coatings available. Another choice is brushing or troweling on stucco or plastic stucco-like materials. (Send inquiries to James Dulley, The Free- man, 6906 Royalgreen Drive, Cincinnati, OH 45244 or visit www.dulley.com.) Some units even come with solar panels www.frigidaire.com A variable-speed compressor can vary the cooling output from 25 percent to full maximum for excellent comfort. www.frigidaire.com This central air conditioner uses a rotary compressor with inverter speed-control technology. Bryant This super-efficient two-level air conditioner uses a simple, quiet two-stage scroll com- pressor. JAMES DULLEY Air conditioning going at the speed you need

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