HVAC Myth-Busting

December 2, 2021

Fact or fiction? Myth or truth? When it comes to technical topics like HVAC, we understand why it’s difficult for homeowners to know which it is. Our technicians spend years learning this trade; they must be NATE certified -- the gold standard in HVAC training -- to work with us, and then receive continuous on-the-job training. The head of our residential department has 30 years of experience (20 full- time and 10 part-time) with a NC H-3 (residential HVAC), NC-SPSH (specialty electrical) and an SC-residential builders HVAC license. In other words, we spend a ton of time gaining education! So, it’s our pleasure to do some myth-busting and demystify the world of home heating and cooling for you.

Myth: The best way to use the setback feature is to set the temperature back as many degrees as you want.

Truth: The setback feature does save some money if you have gas heat but only if you use the setback feature properly, meaning only by 2°. No more than two!  We tell customers to remember that the people telling you to use setback are the same people selling you energy. 

Myth: Windows are the greatest source of heating and cooling loss in my home.

Truth: While this may be true, it’s much more likely that you’re losing more energy out of your ceiling/roof. In the typical home, around half of all heating and cooling loss comes from air leaks and poor insulation in walls and the ceiling/roof. Still, all air leaks around your windows should be fixed. Proper caulking and upkeep will significantly reduce your heating and cooling bills.

Myth: Routine checks are a waste of money. So long as your air conditioner or furnace is running fine, there's no need to have it checked by an HVAC professional.

Truth: Chances are your system is perfectly normal, and, in fact, will be for the foreseeable future. But, a mechanical problem can always arise even as the system functions normally, and you've done everything you're supposed to do. Keep in mind: these machines move the air in your house, so they need cleaning. Think about how often you dust around your house. Guess what?! That same air and dust you removed from tables and surfaces is in your air handler!

So, to ensure long term operating reliability and energy economy, your best move is to schedule an annual maintenance check with a local HVAC expert. They will inspect your system to make sure it's actually fine and running smooth. They'll identify the beginning of long term mechanical problems, nip them in the bud, and ensure you get a lot of years from your system. Even better, their maintenance checks will prevent efficiency decreases due to wear, tear and particulate build up.

Myth: Buying an allergen filter improves air quality.

Truth: These micro-pleated allergen filters may capture more dust at initial pass, but they filter less air than a basic filter over time. Expensive allergen filters cost you a lot of money and bring basically zero benefit. If you want high grade indoor air quality, consider a media filter cabinet. Every Charlotte Mechanical install comes with a 4” Honeywell media filter cabinet, which yields no airflow loss and no equipment efficiency loss. It’s a win-win!

Let us geek out for a moment with more detail for you: 

Let’s say allergen filters reduce airflow by 100 cubic foot per minute (CFM) per grille. Over the course of 90 days of run time you end up losing a lot of cycles of air in the house. These additional losses of air rotation add up big and end up costing you more money in efficiency loss; on the flip side, a more basic filter gets a lot more opportunity to filter air.

Here’s the math for an average home:

  • 2,000 sq. ft. house (8 ft. ceiling average) = 16,000 cubic ft.
  • This house has 2 filter grilles losing 100 CFM per filter (at a minimum) = 200 CFM
  • The average run time during standard weather conditions would be 50% of the day, or 12 hours

Net, net: In this example, a regular pleated 1” filter actually captures more dirt over a three- month period because it has 810 more opportunities to capture dust and dirt.  

[200 CFM x 60 min. = 12,000 (lost CFM per hour) x 12 hours = 144,000 (lost CFM per day) x 90 days =12,960,000 (lost CFM over 90 days) /16,000 cubic ft. = 810 rotations of air through your house.]

Myth: Raising the indoor temperature raises the bill

Truth: Setting the temperature a degree higher or lower doesn’t really affect your bill. What does affect your bill is the outdoor ambient conditions (i.e., the weather). Is it a warm or cold winter day? Did you know that the median temperature for a Charlotte winter is 23° and summer is 91°? We all know that we experience extremes much worse than these. But HVAC equipment is sized for the median, not the extremes. If we sized for the extremes, we wouldn’t be comfortable during the milder days.       

Fun fact: HVAC equipment is sized based off of a book called Manual N or J. These books take over 100 years of data from Army Corp of Engineers’ weather stations all over the U.S. These readings are for every hour of every day, recording temperature, humidity, dew point, etc. in every major U.S. city. 

We are here for all your heating repair, maintenance and installation needs. Contact us anytime, 24/7. Or, curious what’s not true when it comes to sinks, tubs, showers and pipes? Check out our Plumbing Myths to Flush blog.

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