Here are six of the myths homeowners seem to cling to the most, along with the facts technicians present to correct the record:  

Myth 1: Cranking The A/C Way Down Will Cool The House Faster  

Marco Radocaj and his crew at Balance HVAC in Vero Beach, Florida, hear that one a lot. The average daytime temperature in Vero Beach in July is around 88°F, the humidity is high, and even in January, the area sees temps in the 70s, so a/c is more important than heating for Balance customers.  

In reality, Radocaj said, turning the thermostat way down will cause the a/c system to run longer and risks freezing the evaporator coil and overheating the compressor.  

“Think of the thermostat like elevator buttons, not a car’s gas pedal,” Radocaj said. “Whether you’re headed to the second floor or the 20^th, the elevator travels at the same speed.”  

Myth 2: Save Energy By Turning Up The A/C When You’re Not Home, Then Letting It Cool The Home When You Arrive

This one was reported by George “Butch” Welsch, president of Welsch Heating & Cooling Co. in Maryland Heights, Missouri, which also sees a lot of hot and humid weather.  

“This does not save any appreciable operating cost and typically results in an uncomfortable home for at least a few hours after returning the temperature to normal settings,” said Welsch.  

The problem, Welsch said, is that people are used to the idea of turning down the heat at night when the weather’s cold, then turning it up during the day, to save on their bills. But the same kind of reasoning doesn’t apply to a/c, he said.  

“The difference is that a furnace pumps out a lot of heat at 130°, which, when sent into a home where the temperature was dropped to, say, 65°, allows the temperature to return to normal rather quickly,” Welsch said. But an a/c system, moving air at 65°F, for example, can take a long time to cool a home where the daytime temperature had been set to 80°F, he added.  

Myth 3: Heat Pumps Aren’t Effective In Colder Regions  

This one comes from Matt Marsiglio, general manager of Flame Heating, Cooling, Plumbing, and Electrical in Warren, Michigan, and Brian Stack, president of Stack Heating, Cooling, Plumbing, Electrical, which has two locations in Northern Ohio. Stack said it’s the biggest myth his team hears these days.  

When they encounter that objection, Marsiglio said, Flame’s technicians and salespeople share manufacturers’ data about how well new cold-climate heat pumps perform.  

“Heat pumps have come a long way and are able to operate at much lower temperatures (than) in the past while still providing adequate heat output,” said Stack. “We try to put that in simple terms and talk about ‘cold-climate technology’ that has been developed in recent years.”  

Myth 4: Oversized Equipment Will Heat And Cool Better 

Marsiglio mentioned this one too, and Stack said he’s heard it applied to a/c.  

“There is no standard wording, but we try to educate customers about what an a/c system actually does,” Stack said, “humidity control being a top topic.”  

At Flame, Marsiglio said, technicians and salespeople who hear this myth can explain that oversized a/c will not dehumidify properly, leaving the home feeling cold and clammy, and that an oversized furnace can lead to premature heat exchanger failure and a drafty home.  

Welsch reported a different version of the “bigger is better” myth, one related to the size of the equipment itself, not its heating or cooling capacity. Furnaces today are much smaller than they were years ago, he said, and when customers who remember the older models see a new unit, they sometimes think they’re being ripped off.  

Myth 5: The Equipment Brand Is The Most Significant Factor In The Performance Of An HVAC System

Joanna Buglewicz, owner and president of Green Valley Cooling & Heating in Green Valley, Arizona, added this one.   

“Many homeowners come into the conversation focused on brand names, assuming one manufacturer will deliver significantly better comfort or efficiency than another,” she said.  

The truth, Buglewicz added, is that most major HVAC manufacturers offer comparable equipment, and system design and equipment installation are bigger factors in system performance.  

“Proper load calculations, duct design, airflow, and commissioning play a much larger role in long-term performance than the name on the equipment. ... A well-installed system from any reputable manufacturer will outperform a poorly designed or improperly installed system every time,” she said.  

Myth 6: Closing The Doors Of Unused Rooms, Or The Registers In Them, Pushes More Cold Air To Occupied Spaces

Radocaj said this practice disrupts the proper air mixing that a balanced forced-air system produces.  

“Blocking supplies can choke overall airflow, reduce total capacity, and create negative pressure in those rooms,” Radocaj said. “If the bedrooms border attics, garages, or exterior walls, this pulls in hot, humid infiltration — raising humidity and hurting comfort house-wide.”  

Adjusting air flow, he added, should be intentional and follow pre-calculated goals based on the home’s load and occupant usage. “Otherwise, you’re just guessing and hoping for the best,” Radocaj said.