When it comes to heating and cooling your home in Dallas, what you don’t know can cost you… big time. At AC Rescue, we’ve heard it all: “Closing vents in unused rooms saves money,” “You only need to change your filter once a year,” or “If the system isn’t broken, don’t worry about it.”
Sound familiar? These HVAC myths have been circulating for decades, and while they may sound logical on the surface, the truth is they can lead to higher energy bills, reduced comfort, and costly repairs down the road.
In this post, we’re breaking down seven of the most common HVAC myths, explaining why they’re false, and showing you what to do instead. Whether you’re a new homeowner in Dallas-Fort Worth or simply want to make smarter decisions about your HVAC system, this myth-busting blog post will help you save money, improve efficiency, and stay comfortable year-round.
Myth #1: Bigger HVAC Systems Work Better and Faster
The Belief: Many Dallas homeowners think a larger HVAC system will heat or cool their homes faster and keep them more comfortable during those blazing Texas summers.
The Truth: Bigger isn’t always better, especially in HVAC. In fact, an oversized system can do more harm than good. When an AC unit is too large for your home, it tends to short cycle. That means it turns on and off frequently without completing a full cooling (or heating) cycle.
Why That’s a Problem:
- Uneven temperatures: Your home may feel chilly one moment and humid the next.
- Poor humidity control: Quick cycles don’t allow enough time to dehumidify, leaving the air sticky.
- Higher energy bills: Starting up consumes more energy than running steadily.
- Wear and tear: All that on-and-off action wears out system components faster.
What to Do Instead: Make sure your HVAC system is properly sized. A professional should calculate the Manual J load, which considers not just your square footage but also insulation, windows, ceiling height, and more. At AC Rescue, our techs perform detailed sizing assessments to ensure your system is just right—not too big, not too small.
Myth #2: You Only Need to Change the Air Filter Once a Year
The Belief: Why change the filter if the air still flows and you don’t see any dust?
The Truth: Air filters are the unsung heroes of your HVAC system. They catch dust, pet dander, pollen, and other airborne nasties. But as they do their job, they clog up. And when that happens, your system has to work harder to push air through—leading to inefficiency and higher energy bills.
What’s at Risk:
- Poor indoor air quality (awful for allergy sufferers)
- Higher cooling costs
- System strain and reduced lifespan
When Should You Change It? In most Dallas homes, if you have allergies or inside pets, change your filter every 30-60 days. Everyone else can probably get by changing it every 90 days, although more often is better.
Bonus tip: Consider upgrading to a high-quality pleated filter. Just ensure it’s the right MERV rating for your system—if it is too dense, you’ll restrict airflow.
Myth #3: Closing Vents in Unused Rooms Saves Energy
The Belief: You’re not using the guest bedroom or the office—why cool them?
The Truth: Closing vents seems like a good way to cut back, but it disrupts your HVAC system’s airflow balance. These systems are designed to deliver air evenly throughout the house. Blocking vents increases air pressure in your ducts, potentially causing leaks or damaging the blower motor.
Common Side Effects:
- Increased ductwork pressure
- Hot and cold spots throughout the house
- Higher utility bills
- Shortened system lifespan
What to Do Instead: Keep vents open, even in unused rooms. Install a zoned system for better room-by-room control. Use a programmable or smart thermostat to strategically manage temperatures during the day.
Myth #4: Setting the Thermostat Really Low Cools the House Faster
The Belief: It’s 98° in Dallas, and your house feels like an oven. Set the thermostat to 60°, and it’ll cool faster… right?
The Truth: Nope. Your HVAC system doesn’t work harder or faster just because you lowered the thermostat more. It cools (or heats) at the same rate regardless of the setting. The only thing setting it lower does is keep the system running longer, which wastes energy and can make the house uncomfortably cold.
What You Should Do: Set your thermostat to your ideal comfort level—typically 74–78°F for cooling. Use a smart thermostat to schedule cooling based on when you’re home. Improve system efficiency by making sure your thermostat is installed properly.
Myth #5: HVAC Maintenance Is Only Necessary When Something Breaks
The Belief: “If it ain’t broke, don’t fix it.”
The Truth: Waiting until your system breaks is like never changing the oil in your car until the engine seizes up. Your HVAC system needs routine checkups to keep everything running smoothly. Preventative maintenance keeps your system clean, efficient, and less likely to break down—especially when you need it most.
Here’s What You’re Risking by Skipping Maintenance:
- Higher utility bills
- Poor airflow and comfort
- Shortened equipment lifespan
- Expensive emergency repairs
Schedule HVAC maintenance twice a year. Once in the Spring, to get your AC ready before the heat hits. Then again in the Fall to prep your heating system for winter chills.
At AC Rescue, our maintenance plans include priority service, discounts on repairs, and peace of mind all year long.
Myth #6: Duct Tape is Fine for Fixing HVAC Leaks
The Belief: It’s called duct tape… it should work on ducts, right?
The Truth: Ironically, duct tape is one of the worst choices for sealing HVAC ductwork. It degrades quickly under heat and pressure, often falling off within weeks.
The Real Fix: Professional HVAC sealing uses specialized materials such as mastic sealant and foil-backed tape designed for HVAC use and high-heat environments.
Why Duct Leaks Matter in Dallas: Leaky ducts can lose up to 30% of your heated or cooled air, meaning more strain on your system and higher energy bills. If you suspect leaks, schedule a duct inspection and sealing service with a licensed pro.
Myth #7: All HVAC Technicians Provide the Same Quality of Service
The Belief: As long as someone can fix the AC, it doesn’t matter who I call.
The Truth: Unfortunately, not all HVAC companies are created equal. Poor installation or repair work can cost you thousands in the long run. From misdiagnosing issues to installing the wrong equipment size, inexperience or carelessness can cause more harm than good.
At AC Rescue, we pride ourselves on top-tier customer service, honest communication, and skilled technicians who know how to fix it right—the first time.
Bonus Tips for Smarter HVAC Use in Dallas
Beyond busting the myths, here are some simple strategies you can use to get the most from your HVAC system:
- Seal your home: Check weather stripping around doors and windows to prevent cool air from escaping.
- Use ceiling fans: Run them counterclockwise in summer to boost circulation and reduce the strain on your AC.
- Close blinds during the day: Block direct sunlight to keep indoor temps cooler.
- Insulate your attic: Many homes in North Texas have under-insulated attics, which let valuable conditioned air escape.
- Upgrade your thermostat: Smart thermostats can cut cooling costs by up to 10% annually.
<2.Final Thoughts
Whether you’re cranking the AC during a hot Dallas summer or warming your home on a chilly winter night, your HVAC system plays a central role in your family’s comfort. But making decisions based on old wives’ tales or outdated advice can cost you.
At AC Rescue, we’re here to help Dallas homeowners cut through the confusion, avoid costly mistakes, and get the most value out of their heating and cooling systems.
Whether you’re due for a maintenance check, considering upgrading your system, or just having questions, our certified HVAC technicians are ready to help. Call AC Rescue today or schedule your service online! Let us rescue your comfort and your wallet.