Picture a time before central heating or air conditioning, when fireplaces or crude stoves heated the center of the house or, if you were really lucky, perhaps the bedroom. Cooling in the summer was unheard of, unless you plunged into the river like Huckleberry Finn or could afford servants standing around fanning you like a member of royalty. Temperature was governed by the seasons, and humans simply learned to cope.
Today, in contrast, we have it easy. That is, it’s so easy that your heating and cooling system is often overlooked – almost an afterthought – until suddenly the furnace doesn’t heat or the cold air doesn’t blow. (And it’s kind of like a law that it has to break down when you need it most.) While there are no guarantees when you are dealing with mechanical equipment, understanding your system and scheduling proper preventative maintenance goes a long way toward keeping your heat and air system – often referred to as HVAC – healthy and strong.
How Your Air Conditioning and Heating Works
Furnaces and central air conditioning units are joined together and controlled first by the thermostat mounted somewhere inside your home. As the temperature rises or falls, the thermostat generates a signal to either the furnace or the central air via a small wire. The appliance, in response, turns on and prepares to deliver either hot or cold air.
A central air conditioning system circulates refrigerant through a condenser, located in the exterior portion of the central air unit, where it is first compressed and subsequently sent to the evaporator inside. There, the blower motor attached to the furnace forces air across the cold coils filled with compressed refrigerant. As the air blows, the coils heat up and the cool air is carried away. The now-warm refrigerant cycles back to the compressor again while the cold air flows out of the home’s vents.
Although there are many types of furnaces, each operates in a basic manner as well: When the thermostat signals the furnace that air temperatures have cooled, the furnace kicks on and turns up the heat source inside the appliance. Then, at a given temperature, a fan blows, forcing air across the now-heated elements. This heat subsequently escapes through the same ducts and vents the air conditioner uses in the summer. The furnace continues through a cycle before the heating stops, the air kicks off, and the unit waits again for the next signal.
Central Air Conditioning and Heat Efficiency
Up to half of your energy bill each month goes toward your heating and air conditioning, as the EPA explains. Today it’s more important than ever before, in light of rising energy costs and increasing environmental awareness, to operate an energy-efficient heating and cooling system.
Appliance efficiency relies on several factors: unit sizing, proper installation, ongoing maintenance, and basic energy-conserving practices inside the home. Most people have little influence on the installation, other than hiring a reputable professional qualified to perform the work (there’s really no short-cuts here; you get what you pay for). Regular inspection and maintenance, however, are elements directly in your control and require little time or money investment.
Energy experts suggest that the average homeowner can reduce heating and cooling costs by up to 30 percent with an efficient system. That’s a savings that your pocketbook will thank you for, as well as the Earth.
Don’t let anyone fool you – sizing either a furnace or a central air unit is complicated. While some homeowners and “backyard” installers try to take shortcuts, using a conversion chart or a simple calculation of a given number of BTUs per square foot of home area to determine the unit size, the results are often inaccurate, and inaccuracy translates into cost. As with professional installation, you get what you pay for, so spend the money to have the furnace and central air properly sized before buying a new unit or upgrading the one you have.
This is one of those cases where more and bigger is not better. Over-sized heating and air units reach the desired temperature too quickly, causing them to cycle on and off constantly, use more energy and, in the case of the air conditioner, fail to remove excess moisture. Undersized units struggle to keep up, often failing to maintain the desired temperature and running constantly in the process. Both conditions cause excessive wear and tear on the unit, higher electrical bills and more frequent service calls on top of a shortened life expectancy for the unit. Both your comfort and your wallet suffer.
A qualified HVAC technician will assess your house to determine the unit size you need, using your square footage and the average temperature in your area along with energy-loss factors such as the ceiling height, amount of shade, window area, amount of insulation in your home and more. A professional can also guide you in evaluating heating and cooling equipment, choosing the unit and efficiency level – called the SEER rating for air conditioning and the HSPF or AFUE rating for furnaces – best suited for your situation. While higher ratings indicate improved efficiency, these ratings reflect ideal, laboratory-created conditions. Real life situations usually vary far from ideal, meaning in some cases, the higher cost of the highest-rated unit may not be recouped in the energy savings achieved.
A word on choosing a heating and cooling professional: The cheapest, once again, may not be the one you want installing or working on your equipment. Before hiring any technician, ask around about the person or company’s reputation. Check with the Better Business Bureau to find any complaints. Find out what ongoing training the technician attends. Ask for a detailed estimate before the work is performed. Most importantly, ask how the work will be performed, step by step, and what tests and adjustments are necessary to assure safe and energy-efficient operations.
Central Air Conditioning and Heat Maintenance
A properly installed unit is only half the battle. Keep your system operating at peak efficiency and save on unnecessary repair bills by inspecting your system regularly. Ideally, hire a service professional to inspect your central air system at the beginning of summer and your central heat when it grows cold late in the year. While you can perform a system check yourself, HVAC contractors are better suited to take an in-depth look at your entire system. So-called “tune-ups” inspect and seal the duct work, if necessary, along with measuring the system’s air flow, measuring coolant levels and testing the compressor as well as other mechanical parts. At minimum, have an initial evaluation performed and repeat every few years as possible. In between, do your own inspections and maintenance.
- Clean any exposed unit surfaces, both inside and out. Leaves, pine needles, vines and debris can quickly smother the central air unit outside and dust or hair can affect the furnace indoors.
- Change filters at least twice a year or more often as needed. Glancing at your filters every month or two takes but a second and potentially saves you a tremendous amount of money.
- Turn on the furnace or air conditioner in advance of the upcoming season and listen for abnormal sounds, smells or behavior. Consult a professional immediately if the system reacts alarmingly or emits strange sounds and odors.
- Check your thermostat yearly to ensure accuracy. Simply compare the temperature reading to the display on another thermometer. Change batteries in programmable thermostats yearly as well to ensure consistent, proper heat and cooling control.
Troubleshooting Your Air Conditioning and Heat System
If your system refuses to work, try troubleshooting before calling a professional. Many times there’s a simple solution, and if the problem is more complex, at least you can point the technician in the right direction.
If your HVAC system doesn’t turn on, the first thing to check is the thermostat. Is it on and set properly? Is the blower control switch in the proper position? Has the temperature setting been accidentally moved? Try turning the thermostat on and off to reset the electronics and possibly fix the problem. In the worst case scenario when something needs replaced, the thermostat is what you want to fail. Installing a new one is a fairly easy repair.
Another common failure is a blown fuse or tripped breaker. Furnaces and central air units draw a tremendous amount of power. Older units draw even more, and older homes may have difficulty handling the demands. Look inside your home’s master electrical box to see if the fuse controlling the system is bad or if the breaker switch is out of alignment with the others. Replace or flip as necessary. Some units may have fuses and switches in other location near or inside the unit itself. Look beside the furnace for a blower switch or a furnace power control. Inspect the pilot light if the blower works but the air isn’t warm. Consult a professional for more information and in-depth repairs.
Sometimes a central air system simply freezes up. If the unit runs when the temperatures are too low outside, the system may be undersized or the coolant levels too low, among other causes. The unit can actually ice over and refuse to work immediately. The solution is turning off the air for a few hours and letting it warm up again. However, this may be a temporary fix at best as it is likely to freeze up again. Find a qualified professional to evaluate your system in the meantime.
Finally, understand that all things have a life expectancy – even your heating and cooling system. If major components fail or your system needs frequent repair, it may be time to send it to the appliance graveyard in the sky and purchase a newer, more efficient one. While many experts recommend replacing central heat and air units every 10 to 15 years, ones built before about 1980 are likely to be terribly inefficient. Balance the system cost against the potential repair and energy savings to make your final decision.