HVAC Pros Are Experts—But in What?

HVAC professionals know their stuff. They have specialized tools, years of experience, and deep knowledge of heating and cooling systems. When you hire one, they’re going to get the job done. But what exactly are they experts in?

It’s not engineering. It’s not efficiency. It’s comfort.

The Industry’s Prime Directive: Keep You Comfortable

Let’s be clear: HVAC pros are not trying to scam you. They’re not selling snake oil. Their job is to ensure that, no matter what, your home stays warm in the winter and cool in the summer. And in Chicago—where winters can be brutal—comfort means never, ever risking a situation where your furnace might not be enough.

So how do they ensure comfort? By oversizing your furnace.

An oversized gas furnace is the most reliable tool in their arsenal. It’s the sledgehammer approach to heating. You’ll never have to worry about whether it can keep up because it will always have more capacity than you actually need. And from a comfort perspective, that makes total sense.

The Hidden Costs of Comfort-First Thinking

But here’s the thing: designing for comfort alone often means sacrificing efficiency. A bigger furnace cycles on and off more frequently, leading to:

Higher upfront costs (bigger units cost more)
More energy waste (short, inefficient run cycles)
Uneven heating (blasting heat for short bursts rather than steady warmth)
More wear and tear (starting and stopping more often)

None of this is a problem from the HVAC professional’s perspective because your house will always be warm—and that’s what they’re selling.

The Chicago Factor: Why Oversizing Is the Default

Here, where subzero temperatures are a real threat, HVAC pros lean even harder toward oversizing. If you’re uncomfortable for even one day of the year, it reflects poorly on them. The safest bet is to install a furnace so powerful that it never even comes close to struggling—even if that means it’s wildly oversized for 99% of the winter.

Additionally, natural gas is cheap here. Homeowners aren’t feeling the inefficiencies in their wallets, so there’s little push to optimize. At the same time, electricity is also relatively cheap, which makes electrification more viable. But again, the HVAC professional isn’t there to sell you something nerdy. They’re not running cost-benefit analyses or thinking about long-term efficiency. They’re there to sell you something effective, something that works, something that won’t fail when it’s -10°F outside.

Data Over Assumptions

But what if we questioned it? What if, instead of assuming we needed the biggest, most powerful furnace that would fit, we looked at real data? What if we analyzed actual heating needs instead of just trusting the biggest hammer in the toolbox?

My analysis told me something surprising: my house didn’t need anywhere near as many BTUs as my furnace was capable of delivering. Even on the coldest days, my furnace wasn’t running 24/7—it had way more capacity than was necessary.

HVAC Experts Are Right—But Also Wrong