Common problem · This week

Furnace starts and stops every few minutes?

Short cycling wears out the parts that cost the most. It usually means the furnace is overheating, and there are three common reasons.

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

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How urgent

Book this week. Every start is the hardest thing your furnace does.

Call if: It cycles more than 4 times an hour
Call if: You see soot or smell burning
Call if: The limit switch keeps tripping

(720) 447-0177

What it usually is

The causes, most common first.

1

Restricted airflow

A clogged filter or closed vents make the furnace overheat and trip its limit switch.

A filter, or the $99 tune-up
2

Oversized furnace

Common in Denver. A furnace too big for the house heats it too fast and shuts off. Fixable with staging or a right-sized replacement when the time comes.

We show you both options
3

Not derated for altitude

At 5,280 feet an un-adjusted furnace runs hot, soots up, and trips early.

A gas-pressure adjustment

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
Replace the filter.
2
Open every supply vent and make sure returns aren’t blocked by furniture.
3
Note how long it runs before stopping: under 5 minutes is short cycling.

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 Short Cycling, answered.

Will short cycling break my furnace?

Over time, yes. It stresses the igniter, blower, and heat exchanger. Fixing the cause early is far cheaper than the parts it eventually kills.

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.”

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