Common problem · This week

Banging, rattling, or squealing furnace?

Every noise means something specific. Match the sound and you’ll know how urgent it is.

$99 diagnostic, credited to the repair
Same-day across Denver
No overtime fees

Get Help Fast (720) 447-0177

How urgent

Turn it off if it’s loud, then book. Small part now, big part later.

Call if: A boom on every startup
Call if: Grinding or metal-on-metal
Call if: The noise is new and getting louder

(720) 447-0177

What it usually is

The causes, most common first.

1

Boom on startup

Delayed ignition. Gas builds up, then lights all at once. It’s stressing the heat exchanger. Call soon.

A burner cleaning and adjustment
2

Rattling

A loose panel, screw, or duct. Harmless, annoying, and quick to fix.

Usually part of the $99 visit
3

Squealing or screeching

A blower motor bearing or belt on the way out.

A motor or belt repair
4

Clicking that never lights

The igniter is trying and failing.

An igniter, usually on the truck

Every fix gets a written price before any work. The $99 diagnostic is credited toward it.

Try this first

What to check before you call.

If one of these fixes it, great. If not, you’ve saved us five minutes on the diagnosis.

1
Note when it happens: startup, running, or shutdown.
2
Check that the filter door and panels are latched.
3
If it booms or grinds, turn it off at the thermostat.

Who we are

Hello. We’re Duality.

Duality Heating and Air LLC is a Denver heating and cooling company run by one licensed technician and the people he trusts. We fix furnaces, ACs, heat pumps, and the air in your home, and we do it the way we’d want it done at our own house. Comfort, in perfect balance.

Denver-based

One technician who lives here, not a call center in another state.
Price in writing

You approve the number before we touch a tool. It never changes.
Fix before replace

We repair what can be repaired and show you both numbers when it can’t.

Questions

Furnace Making Noise, answered.

Is a loud furnace dangerous?

A boom on startup can crack the heat exchanger over time, which is a carbon monoxide risk. Have it checked soon.

From Denver neighbors

HVAC service

Cecilia Gomez
Google review

“Professional, knowledgeable, and incredibly helpful. He took the time to explain everything clearly, answered all of my questions, and made the entire process easy and stress-free. I truly appreciated his honesty, responsiveness, and attention to detail.”
AC repair

Jessica Russman
Google review

“Very honest and reliable. He showed up on time and fixed our old AC after we had several companies try to sell us a new one. We would 1000% recommend Duality to anyone who wants to feel confident they’re dealing with the right company.”

Same-day help