Improving AC Operation

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Air Conditioning Systems / Operating Cost Tips

Here are some tips that can help keep your operating cost low without sacrificing comfort. How you operate your air conditioner can make a big difference in what it costs to cool your home.

A) – In mild weather, using natural ventilation or fans at night, and keeping the house closed during hot days, is usually less expensive than operating an air conditioning system. Use air conditioning only when ventilation can’t maintain comfort. Every time the outside air is brought into the home, the air conditioner must work extra hard to remove the moisture in it. if your air conditioner has an option to bring in outside air, use it sparingly. During extremely hot, humid times of the year, it is usually more efficient to seal up the home and air condition around the clock. It is far more economical to recirculate and cool the indoor air than to cool the hot outdoor air down to comfortable temperatures and remove the moisture in it.

B) – Be sure all air conditioner ducts passing through unconditioned basements, crawl spaces, and especially attics are well sealed and insulated. Keep all doors and windows closed tightly when operating an air conditioner.

C) – Don’t cool unoccupied rooms, however, with central systems, don’t shut off registers because closed registers increase system pressure, which can damage the compressor.

D) – Moving air with ceiling fans can increase the comfort range. Keep thermostat settings at 78° F or higher. And remember, you save 6% to 8% on air conditioning costs for each degree the thermostat setting is raised.

E) – Keep as much moisture out of the house as possible. Another way to improve comfort at warmer temperatures is by reducing humidity. Run a bathroom exhaust fan while showering, be sure your clothes dryer is vented to the outside, and keep house plants outside during the summer. Most of the water you pour on them ultimately ends up in the air and must be removed by the air conditioner when it is running.

F) – Air conditioners and heat pumps need regular maintenance in order to perform at top efficiency. The condenser should be cleaned by a professional every other year, or even yearly in dusty conditions. They should never be allowed to get dirty enough to restrict air flow, which can damage the unit.

Central air conditioning units should be inspected and tuned by a professional once every two to three years. While servicing your unit, don’t have the refrigerant charge checked unless the need to do so is indicated on the Total Performance Diagnostic Report. The charge impacts how efficiently your air conditioner operates but excessive checking may actually lead to a low charge due to refrigerant that is released each time the system is checked. A system undercharged by 10% can operate at a 20% lower efficiency and overcharging can damage the unit and reduce its life. The service technician will also check the temperature difference between the air entering wet bulb and leaving the air conditioner wet bulb. If it is greater than required, air circulation may be inadequate. The rate of air flow must be matched with the unit’s capacity. If the air moves too fast over the cooling coil, it will not be sufficiently dehumidified, and too little air can result in ice forming and blocking the coil.

G) – To achieve its greatest efficiency, the outside part of an air conditioning system, the compressor and condenser coils, should be located in a cool, shaded place that allows good ventilation. The best place is usually on the north side of the house under a canopy of trees or tall shrubs. . Sunlight hitting the condenser unit will heat it up and reduce its ability to exchange heat. Be sure bushes and other vegetation do not choke air flow. The compressor needs good air circulation around it to effectively exchange heat with the outside air.

With heat pumps, because they heat and cool, location of the outside unit is a little more complicated. Heat pump compressors should be located on the south side of the home, especially in colder climates, so they can take advantage of winter solar heat gain. In the summer, it should be shaded with a sunscreen or tall deciduous vegetation.