7 HVAC Mistakes That Drive Up Summer Cooling Costs

If you’re interested in getting your air-conditioning costs under control, keep reading. You may be surprised to learn that a few of your bad habits may be sabotaging your savings plan.

This post has been brought to you by Sears Home Services. Its facts and opinions are consistent with those of BobVila.com.

  1. Start Your Air-Conditioning Audit Today

    Start Your Air-Conditioning Audit Today

    Are you paying a king’s ransom in utility bills every month just to keep your house comfortably cool? Most homeowners are unaware that they're inadvertently contributing to higher-than-necessary air-conditioning costs. We consulted Craig Marin, Director of the HVAC Product Line for Sears Home Services, to find out what kinds of mistakes can raise energy bills in the summer months and how homeowners can course correct.


  2. 1. Neglecting Maintenance on Your HVAC Unit

    1. Neglecting Maintenance on Your HVAC Unit

    The number one mistake Marin sees homeowners making that drives up their cooling costs is failing to maintain their HVAC unit. “Units get dirty,” he explains, “and unless they’re cleaned, they’ll have to run longer and harder, making them a lot less efficient.” While most HVAC manufacturers recommend that homeowners have their units professionally inspected and maintained before summer and at least once per year, Marin recommends a second checkup in the fall to make sure that the HVAC system got through the summer without developing a problem that could hamper winter heating.

    Sears Home Services recognizes that many homeowners don't bother servicing their HVAC units until something goes wrong, so they’ve launched an HVAC loyalty program to incentivize regular HVAC checkups. Through the program, for every dollar spent when you call Sears Home Services to come out and maintain or repair your existing HVAC unit, the company will put an equal dollar amount into an account toward installing a replacement HVAC unit down the road. (This amount can be up to 10 percent of the purchase and installation price of the new unit.) For homeowners, it’s a win-win situation—their existing units will run more effectively, and they’ll also save money when it comes time to buy a new system.

    RELATED: 7 Important Reasons Never to Skip Your HVAC’s Yearly Checkup


  3. 2. Forgetting to Change Air Filters

    2. Forgetting to Change Air Filters

    To perform efficiently, an AC unit needs an unencumbered flow of air across its internal coils. When air filters become clogged with dust and dirt, the AC unit struggles to draw in adequate air, and, as a result, the unit no longer functions at capacity. When this happens, the air conditioner will have to run longer to cool the interior of the home to the target temperature. Air filters are inexpensive, from $3 to $5 for a standard filter, so there's no good reason not to change them at the start of each new season (four times each year). Doing this simple maintenance task will help your HVAC system run more efficiently and enable you to save on cooling costs. Sears Home Services makes it easy for you: Sign up for the filter subscription plan through Sears PartsDirect, and the filters will be delivered to you right when you need them.


  4. 3. Starting with an Oversize HVAC System

    3. Starting with an Oversize HVAC System

    It’s a common misconception that a bigger HVAC unit translates into better cooling in your home. In fact, Marin says that the purchase and installation of oversize units is a “big problem in the industry.” When contractors replace an existing HVAC unit with a new one of the same size, it's important to realize that a “20-year-old 3-ton unit isn’t as powerful as a modern 3-ton unit.” In the end, a homeowner could end up with a unit that is too large for the home.

    So, what's the problem? When an HVAC unit is larger than necessary, it will cool the interior of the home quickly, but it won’t reduce the humidity levels in that short time as well as it could if it had run longer. Air conditioners ensure comfort not just by cooling the air, but also by removing humidity from the air. When the AC isn't removing enough moisture from the air, the occupants of the home won’t feel comfortably cool. In response, they’ll set the thermostat even lower, forcing the oversize unit to run longer and waste energy.

    When you're sizing your home for an HVAC unit, a residential load calculation should always be performed. Also called a “Manual J” calculation, this involves a Sears Home Services technician recording and analyzing everything that might affect your home’s cooling needs, from square footage and the number of windows to the home’s location and method of construction. “The more accurate the size of the system, the more efficient it will be,” Marin says.

    RELATED: Need a New AC? 5 Top Factors for Sizing Up Your Needs


  5. 4. Shutting Off Vents

    4. Shutting Off Vents

    Many homeowners think that if they want to save on cooling costs, they can simply shut off the vents in rooms that aren’t frequently used. While it's tempting not to waste money cooling empty rooms, don't close those vents—these systems are designed to circulate air throughout the entire home. “An HVAC system is sized for the ductwork,” Marin says, “and when you close down the amount of air, the system can freeze up”—and quite literally so. Your system draws warm air out and replaces it with cool air. When you close off a vent, you reduce air circulation in that room, which means that, overall, less warm air is being drawn across the system’s coils. This causes the coils to get colder and colder until frost develops. When a layer of frost develops on the coils, they can no longer cool the air as effectively as they did before, pushing your entire HVAC system into overdrive to maintain a comfortable interior temperature.


  6. 5. Not Using a Programmable Thermostat

    5. Not Using a Programmable Thermostat

    A standard nonprogrammable thermostat keeps your home’s interior at a set temperature until you manually adjust it. While this is a simple way to operate your HVAC system, it’s not cost-effective. Too often you end up cooling your home for hours while you’re at work and no one is home, which translates into unnecessarily high cooling costs.

    Instead, install a programmable thermostat that allows you to set temperatures for particular times of the day that correspond to your schedule—then actually make the effort to program it! “Programmable thermostats will help you save money only if you program them,” Marin says. Many homeowners don’t bother to learn how to program their thermostats, and this makes a programmable thermostat no better than a nonprogrammable one. So, if you install a programmable thermostat, take a few minutes to go through the owner’s manual and learn how to program it. This will pay off (literally!) in savings on your utility bills.

    RELATED: The New Cool: 3 Ways Air Conditioning Has Changed for the Better


  7. 6. Hiding the Outdoor Unit

    6. Hiding the Outdoor Unit

    We get it: Outside HVAC units are neither beautiful nor worthy of a prime spot in your landscape. Yet, while erecting a fence or planting bushes around your unit might hide it attractively from view, doing so can also reduce its efficiency and force your air conditioner to work harder, use more energy, and cost more to run.

    According to Marin, outdoor HVAC units need “room to breathe, at least two to three feet around all sides.” Camouflaging the unit reduces the amount of air it can draw, which starves the unit for air (just as if you had forgotten to change the air filters), and may put its coils at risk of freezing. Not only will this increase your energy costs, but the undue stress could also reduce the unit's useful life.


  8. 7. Not Ventilating the Attic

    7. Not Ventilating the Attic

    Attic ventilation is an out-of-sight, out-of-mind problem for most homeowners, but Marin warns them that not adequately ventilating the attic can really affect cooling costs. Non-ventilated attics can reach upward of 150 to 180 degrees Fahrenheit on a hot summer day. That extreme heat radiates downward through the ceiling and into the home’s framing, raising indoor temperatures on the living levels. In order to cool a home with an unvented attic, the AC needs to work overtime—and that can translate into outrageous utility bills.

    Most of today’s building codes for new construction require builders to install ventilation in attics, but if you have an older home, or if the ventilation was blocked during remodeling at some point, it’s a good idea to have your attic vented now. In addition to saving on cooling costs, you’ll prolong the life of your roof.


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