3 HVAC Myths You Should Stop Believing

Your home’s heating, ventilation, and air conditioning (HVAC) system is one of its most important and expensive components. It is the silent workhorse that keeps your family comfortable through the sweltering, humid summers and the cold, bitter winters we experience here in the Chesterfield area. Because this system is so critical and complex, a great deal of “common knowledge” and advice gets passed around among homeowners, friends, and online forums.

While this advice is almost always well-intentioned, much of it is based on persistent and pervasive myths about how HVAC systems work. Believing these myths can lead homeowners to make decisions that, at best, waste a significant amount of money on their utility bills and, at worst, can cause serious damage to their valuable equipment. Separating fact from fiction is the key to making smart, informed decisions that will improve your home’s comfort, lower your energy costs, and protect your HVAC investment for years to come.

Myth #1: A Bigger HVAC System Is Always Better

This is perhaps the most common and intuitive myth in the entire HVAC industry. The logic seems to make sense: a more powerful air conditioner or furnace should be able to heat or cool a house with less effort, leading to better performance, right? It is easy to think of it like a bigger engine in a car, providing more power when you need it.

The reality, however, is that this “bigger is better” mindset is the root cause of many of the most common comfort and efficiency problems a homeowner can face. An oversized HVAC system is a major and costly problem. In the summer, an oversized air conditioner will blast your home with a huge volume of cold air, causing the temperature to drop very quickly. This satisfies the thermostat in just a few short minutes, and the system shuts off. A few moments later, the temperature begins to rise, and the cycle repeats. This constant on-and-off process is known as short cycling.

This is incredibly inefficient. The startup phase of an air conditioner’s cycle is its least efficient part, and a system that is constantly starting and stopping is like driving a car in heavy city traffic instead of cruising on the highway; it wastes a tremendous amount of energy. Even more importantly for our humid St. Louis climate, this short cycling has a devastating impact on your comfort. Your air conditioner’s other critical job is to dehumidify your home’s air, and this is a process that requires long, continuous run times. An oversized unit that only runs for a few minutes at a time will not have a chance to remove the sticky humidity, leaving your home feeling cold, damp, and clammy. This constant on-and-off action also places an immense amount of wear and tear on the system’s compressor, leading to more frequent repairs and a dramatically shortened lifespan.

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Myth #2: Closing Vents in Unused Rooms Saves Money

This is another myth that seems to be based on simple, straightforward logic. If you have a guest bedroom, a home office, or another room that you are not using, why should you pay to heat or cool it? It seems like a smart and easy way to save energy to simply close the supply air vent in that room and shut the door.

In reality, this is one of the most counterproductive things you can do to your HVAC system. A residential forced-air system is engineered by designers to be a balanced, closed-loop. The blower fan is sized to move a specific volume of air, and the ductwork is designed to distribute that air throughout the house against a specific amount of internal pressure, known as static pressure. When you close off one or more vents, you are fundamentally disrupting this carefully engineered balance.

Closing vents creates a significant increase in the static pressure inside your duct system. Your furnace or air handler’s blower fan is now trying to push the same amount of air through a much smaller and more restrictive set of pathways. This is like trying to exhale forcefully while pinching your nose. This places a major strain on your system’s blower motor, forcing it to work harder, consume more electricity, and burn out prematurely.

This high pressure can also force more of your expensive, conditioned air out of any small, pre-existing leaks in your ductwork, often into your unconditioned attic or crawlspace. Most dangerously, the reduced airflow across your system’s coils or heat exchanger can cause it to malfunction. In the summer, it can cause your indoor air conditioner coil to freeze into a solid block of ice. In the winter, it can cause your furnace’s heat exchanger to get dangerously hot, which can trip a safety switch or even lead to a crack over time. The correct way to control the temperature in different areas of your home is with a professionally installed zoning system, not by arbitrarily closing vents.

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Myth #3: Annual Maintenance Isn’t Necessary If the System Is Working

This is the classic “if it ain’t broke, don’t fix it” approach to home maintenance. Many homeowners assume that as long as their furnace or air conditioner is turning on and producing warm or cool air, there is no need to pay for an annual professional tune-up. They view maintenance as an unnecessary expense and decide to wait until something actually breaks before they call for service.

This reactive approach is one of the costliest mistakes a homeowner can make. A professional tune-up is not a repair for a broken system; it is preventative care designed to keep your system from breaking in the first place. An HVAC system can operate for months or even years with developing problems that are completely invisible to a homeowner. It may be running with a failing capacitor, a loose electrical connection, a dirty burner, or an incorrect refrigerant charge. While the system may still be “working,” it will be doing so inefficiently, with increasing strain on its components, and with a growing risk of a sudden, catastrophic failure.

During an annual maintenance visit, a certified technician from Lolich HVAC performs a comprehensive series of cleanings, adjustments, and safety checks. They will clean the indoor and outdoor coils to prevent the loss of efficiency caused by a buildup of dirt. They will check and tighten all electrical connections to prevent motor failures. For a furnace, they will clean the burners to ensure clean combustion and, most critically, perform a visual inspection of the heat exchanger to check for any dangerous cracks that could leak carbon monoxide. An annual tune-up is an investment that pays for itself by keeping your system running at its peak efficiency, which lowers your utility bills. It catches small problems before they can become huge, expensive emergency repairs, and it is also required by most manufacturers to keep your valuable parts warranty valid.

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Your home’s HVAC system is a major investment, and its performance and longevity are directly tied to how it is operated and maintained. By moving past these common myths and embracing the facts, you can make smarter and more cost-effective decisions for your home. A properly sized system is always better than an oversized one, a balanced and open duct system is essential for airflow, and a commitment to annual, professional maintenance is the key to reliability and efficiency.

The world of home comfort can be a confusing one, but you do not have to navigate it alone. If you are a homeowner in the Chesterfield or greater St. Louis area, we encourage you to rely on expert, factual advice for all of your HVAC decisions. Contact the trusted professionals at Lolich HVAC to protect your investment, improve your comfort, and ensure your system is operating as safely and efficiently as possible.