SUMMARY: This blog debunks six common HVAC industry myths that can lead to inefficiency, higher costs, and poor system performance in commercial buildings. From misconceptions like closing vents to save energy or skipping preventative maintenance, to underestimating the importance of proper thermostat placement, the post highlights why expert guidance is essential. Donnelly Mechanical emphasizes the value of informed decisions and customized service to help NYC businesses optimize their HVAC systems and avoid costly mistakes.
—
When it comes to commercial heating, ventilation, and air conditioning (HVAC) systems, there’s no shortage of outdated advice and industry myths still floating around. While some of these misunderstandings might seem harmless, many can actually lead to higher energy bills, costly equipment failures, or underperforming systems. At Donnelly Mechanical, we believe that informed building managers make better decisions — and that starts with separating HVAC fact from fiction. Below, we break down some of the most persistent HVAC industry myths and set the record straight.
Myth #1: Closing vents saves energy in commercial spaces
At first glance, this myth seems to make sense. If you’re not using a room, why not close the vents and redirect airflow elsewhere to save energy? Unfortunately, HVAC systems — especially those in commercial buildings — aren’t designed to work that way. Closing vents can actually throw off the system’s balance, increasing pressure in the ductwork and forcing your system to work harder, not smarter.
This increased strain on your HVAC system can lead to premature wear, airflow issues, and even duct leaks. In multi-zone commercial buildings, improper airflow can also compromise comfort and system efficiency. Rather than closing vents, it’s far more effective to work with an HVAC expert to optimize zone controls, thermostats, and airflow settings that support energy savings without damaging your system.
CHOOSING SUSTAINABLE HVAC SOLUTIONS IN NYC: WHAT TO CONSIDER
Myth #2: Preventative maintenance isn’t necessary
Another costly misconception in the HVAC industry is that you only need to service your system when something breaks. The reality is that preventative maintenance is one of the most important investments you can make in your commercial HVAC system. Just like changing the oil in a vehicle, routine maintenance ensures smooth operation and extends the life of your equipment.
At Donnelly Mechanical, we’ve seen firsthand how customized service agreements reduce downtime, increase efficiency, and help avoid expensive emergency repairs. Skipping maintenance may save money in the short term, but it often leads to greater expenses down the line — especially in high-demand environments like New York City commercial buildings, where downtime isn’t just inconvenient, it’s costly.
Myth #3: Air vent filters need to be changed once a year
This myth can be particularly damaging in commercial settings. Changing HVAC filters only once a year is nowhere near often enough — especially in buildings with high occupancy, equipment usage, or environmental pollutants. Dirty filters restrict airflow, reduce efficiency, and contribute to poor indoor air quality, putting both your equipment and building occupants at risk.
In reality, many commercial HVAC systems require filter changes on a quarterly — or even monthly — basis depending on the building type and usage. Our technicians at Donnelly assess each client’s needs individually and recommend a filter replacement schedule that ensures optimal system performance, air quality, and energy efficiency.
Myth #4: Size makes all the difference
It’s a common belief that a bigger HVAC system will always do a better job. But when it comes to HVAC sizing, more isn’t necessarily better. An oversized system may cool or heat a space too quickly, leading to short cycling, inconsistent temperatures, and unnecessary wear on the system. On the flip side, an undersized system will struggle to maintain comfort, running constantly and using more energy.
Proper sizing depends on many factors: building layout, insulation, occupancy levels, equipment load, and even sun exposure. At Donnelly Mechanical, we take a holistic approach to system design, using load calculations and advanced diagnostics to ensure your system is perfectly matched to your building’s unique needs. The goal isn’t just temperature control — it’s energy efficiency, occupant comfort, and long-term reliability.
Myth #5: HVAC technicians are unskilled laborers
This outdated stereotype couldn’t be further from the truth. Today’s HVAC technicians require extensive training, certification, and technical know-how to service modern commercial systems. From handling refrigerants safely to understanding building automation systems and energy codes, HVAC professionals are highly skilled tradespeople whose work directly impacts your building’s performance and compliance.
At Donnelly Mechanical, our technicians go through a rigorous training program to ensure they’re equipped to handle everything from routine service to complex installations. We pride ourselves on delivering HVAC service in NYC that combines deep technical knowledge with a commitment to safety, quality, and professionalism. The next time you see a Donnelly van on the street, know that behind it is a team of experts trusted by over 1,700 commercial clients.
HOW DONNELLY MECHANICAL IS RECRUITING GEN Z FOR HVAC
Myth #6: Thermostat placement doesn’t matter
It might seem like a minor detail, but where you place your thermostat can have a big impact on system performance and occupant comfort. If a thermostat is installed near windows, heat-generating equipment, or exterior doors, it may take inaccurate readings — causing your HVAC system to turn on or off unnecessarily.
Smart thermostat placement is a cornerstone of HVAC system design, especially in large commercial buildings. By placing thermostats in areas that reflect average room conditions, you ensure better system control and more accurate temperature regulation. At Donnelly Mechanical, thermostat strategy is part of our energy solutions approach. We help clients make data-driven adjustments that reduce energy waste and enhance comfort throughout the building.
Debunking Common HVAC Industry Myths
The HVAC industry is filled with outdated advice and long-standing myths — but with the right knowledge, your business can make smarter decisions that benefit both comfort and the bottom line. At Donnelly Mechanical, we’re not just in the business of HVAC — we’re in the business of peace of mind. From transition planning and preventative maintenance to energy optimization and expert service, our team is here to help you avoid the myths and maximize your investment.
Let’s bust the myths, upgrade your understanding, and take your HVAC strategy to the next level. Connect with Donnelly Mechanical today to learn more about how we serve New York City’s most demanding commercial environments.
Get in Touch