Newest air conditioners are ultraefficient
Q: My central air conditioner is 16 years old, noisy and probably inefficient. I want to replace it with a quiet, more efficient model. What are the best ones available and which provide the best overall comfort?
A: If your central air conditioner is that old, any new model you install will be much quieter and efficient. Depending upon its condition, your old one likely has a SEER (seasonal energy efficiency ratio) of less than 10. The most efficient new ones are as high as 24.5 SEER, which would cut your cooling costs by 60% or more.
As with most products, higher efficiency models that provide the greatest savings also cost the most to install. Always request your contractor to provide payback analyses on several models of various efficiencies. With this information and other intangible factors, such as comfort, conservation and environmental concerns, etc., you can make your selection decision.
While you are getting quotations on various systems, also consider installing a heat pump instead of just a central air conditioner. Their cooling efficiencies are only very slightly less and installing one may also cut your winter heating bills even if you have a gas furnace.
Your three basic options are fully variable, two-level and single-level cooling output models. Because 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 that are often called “inverter technology.” They continually vary the cooling output to the instantaneous cooling needs of your house. The cooling level varies in 1% 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 that 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 are the least expensive to install. Because 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.
• Contact James Dulley at 6906 Royalgreen Drive, Cincinnati, OH 45244 or visit www.dulley.com.