A guide to quieter, more efficient central air conditioners
Q: My room temperatures don’t stay very even and my old central air conditioner is getting noisier each year. What types of new systems are more efficient and quieter?
A: A new central air conditioner system can be more than twice as efficient as your old existing one so it will cut your cooling expenses in half while providing better comfort. Central air conditioner efficiency is rated by its SEER (seasonal energy efficiency ratio).
You will also get more constant room temperatures, precise humidity control and quieter operation. 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 furnace takes over. Some companies call this a hybrid system.
Your three basic options are fully variable, two-level and single-level cooling output models. Since you are seeking high efficiency, steady room temperatures, humidity 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 continually vary the cooling output to the instantaneous cooling needs of your house. The cooling level varies in one-percent increments from about 35% 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 efficiently. 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 condenser 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 automatically varies to control humidity. It can continue to dehumidify even when the room air is already cool enough. This eliminates that cool, but muggy feeling which may occur with a single-level system, particularly 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 system runs at the more efficient low-output level the majority of the time. On hot afternoons 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 temperature swing of about two to three degrees between run cycles.
Q: I recently had a house built and the exterior foundation foam insulation is exposed to the weather. Should I cover it with something to protect it?
A: 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 questions to James Dulley, Daily Herald, 6906 Royalgreen Drive, Cincinnati, OH 45244 or visit www.dulley.com.
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