By: NPPD Energy Efficiency Program Manager Cory Fuehrer During this time of the year, many are switching their thermostats from “cooling” to “heating” mode. This is also a good time to check and change filters in heating and cooling (HVAC) systems. Some may have not been replaced since the start of the cooling season or longer. But how important could a filter be if your HVAC system still seems to provide adequate heating and cooling? Consider the following potential impacts: Inefficient heating and cooling The whole reason you have an HVAC system is to keep comfortable inside. Dirty filters reduce airflow and the system’s ability to condition the air in your home. According to the Department of Energy, a furnace or air conditioner with a clogged filter can use 15 percent more energy than one operating with a clean one. Higher cost of utility bills Every year, energy efficiency professionals start hearing concerns about the high cost of utilities after homeowners and renters receive their first bills after an extended cold period. An inefficient HVAC system only makes these bills higher. Uneven temperatures inside Most duct systems are designed with the assumption that, with a clean filter, the furnace or air handler will move an adequate volume of air to keep temperatures balanced throughout your home. Diminished air flows due to a dirty filter often result in a room or rooms not receiving the same amount of conditioned air as others. Short cycling or equipment failure Reduced air flow due to a dirty filter can cause your heat exchanger to overheat and shut off before your thermostat’s setpoint is reached. Over a relatively short period of time, the HVAC system will continue to cycle on and off. If this happens too often, the system’s electronic "limit switch" can fail, and the furnace won't fire up at all. Now, on top of higher utility bills, a HVAC technician will leave one for parts and labor. Of course, Murphy’s Law states this will occur on one of the coldest days of the year and after normal business hours to optimize the technician’s fees. A similar problem can occur in the middle of summer. A clogged filter can cause the evaporator coil to freeze up because not enough air is moving through it to remove condensation produced during the cooling process. This seems to inevitably occur to filter abusers over the Fourth of July weekend in order to once again, optimize the HVAC technician’s fees. Also, dirt that gets past a filter can also make its way into the fan motor and other parts, causing damage to those components. As if the repair bill didn’t cost enough! Puts the burden on your lungs Relying on your lungs to filter out all the contaminants that can potentially be in indoor air could mean you find yourself sick or feeling ill more often. Those contaminants might include: dust, mites, spores, mold, ash, pollen, pet dander, bug parts, hair, lint, tobacco smoke, food particles, pesticides, paint vapors or fumes from cleaning products. A clean filter helps remove these contaminants to create a healthier home. Changing your filter once a year is probably not often enough. However, if you’re not currently changing your filter at all, it’s a start. Some heating and cooling experts recommend replacing your filter every month. While this practice may ensure you never operate your system with a dirty filter, you may be throwing a good filter away prematurely if your indoor air is relatively clean. Instead, check filters monthly for one year until you understand how often needs to be replaced. Some do may require monthly replacement, but if your system operates very little, such as during mild months, you may get additional use from the same filter. Also note that some filters are designed to last multiple months. Only through observation and following manufacturers’ recommendations can you best gauge optimal replacement frequency. Not sure which filter to select? Visit with your HVAC technician or retail expert to assure your selection provides the best filtration possible without negatively impacting your system’s performance. Southwest Public Power District and Nebraska Public Power District want to help you make the most of the energy they provide you. That includes helping you keep your home’s heating and cooling system running efficiently. For other ideas on making your home EnergyWiseSM, contact Southwest Public Power District or visit www.nppd.com.