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Furnace repair in Lone Tree, Littleton and the south Denver metro.

No heat? You call, you talk to the tech. We find the actual fault, quote a flat-rate price before we start, and fix it. No scare tactics about your heat exchanger.

Same-day when the schedule allows Licensed & insured Xcel Energy trade partner
Furnace replacement: Trane furnace installed with sealed ductwork in a Colorado basement by Atlas Mechanical
What we actually find

Why is my furnace blowing cold air or not turning on?

Most no-heat calls in the south Denver metro are one of six failures, and the two most common — a cracked hot surface igniter and a flame sensor coated in oxidation — are inexpensive parts replaced on the same visit. Knowing which is which is how you tell a real diagnosis from a replacement pitch.

Usually cheap

Fires up, then quits

Burners light for thirty seconds and shut down, over and over. Usually a flame sensor coated in oxidation, so the furnace can no longer prove the flame and shuts itself off exactly as designed. Clean or replace it and the cycle ends.

Usually cheap

Clicks but never lights

You hear the sequence start and nothing happens. A cracked hot surface igniter is the single most common no-heat part in the metro. It is a stocked part and typically a same-visit repair.

Airflow

Blowing cold air

The fan runs but the air is cool. Either the burners are not staying lit, or the thermostat fan is set to ON instead of AUTO so the blower runs between cycles. One is a repair and one is a setting, and we will tell you which.

Noise

Rattle, screech or a loud boom

An inducer motor bearing, a failing blower wheel, or delayed ignition where gas builds before it lights. The boom on startup is the one worth calling about promptly rather than living with.

Safety

Heat exchanger concerns

A cracked heat exchanger is a genuine carbon monoxide risk, and it is also the most abused claim in this trade. We show you what we found and why, and we would rather you get a second opinion than take our word for it.

Honest answer

Old unit, repeat repairs

Past fifteen to twenty years, repairs start stacking. When replacement genuinely costs less across the remaining life of the unit, we say so and quote both, and when it does not, we fix the one you have.

Why the setup matters

Does a furnace need to be derated for Colorado altitude?

Yes. Gas furnaces ship set for sea level and have to be adjusted for Front Range elevation. Left on factory settings a furnace burns rich, runs inefficiently, sooties up over time and shortens its own life.

There is less oxygen per cubic foot of air at this elevation, so burner orifices and gas pressure both have to be brought down to match it. The furnace is otherwise being fed more gas than the air around it can burn.

It is invisible from the thermostat, which is why it goes unnoticed for years. We check the setup on repairs where the symptoms point that direction, and we set it correctly on every install, because a system dialed in for the air it is actually breathing is the cheapest performance gain there is.

Heating season here is long and it does not warn you. The furnace that ran fine in October is the one that quits at 11 degrees in January, and it is almost always a part that was already showing symptoms.

Gas settings dialed in for altitudeOrifices and pressure set for Front Range elevation, not left on the factory sea-level configuration.
Flat-rate price before any workYou approve the number first. No hourly meter, no finding out the cost once it is apart.
We show you the heat exchangerIf we call one cracked, you see what we saw. Get a second opinion, and we mean that.
Xcel Energy trade partnerRebate-eligible high-efficiency equipment handled correctly when replacement is the right call.
Real heating calls

What homeowners said after we showed up.

Rated 5.0 on Google across 61 reviews. These two are heating jobs.

Jared installed my furnace and did a spectacular job! Pricing was clear and fair, competitive with other quotes. I appreciate his attention to detail and that he took the time to show me all of the features of our new system.
GS Gabby SegalGoogle review · Furnace install
Since 2011, Jared has installed six furnaces, three air conditioner units and handled HVAC repairs at my rental houses. He continues to be my go-to, and I'd recommend him.
DS David SpaethProperty owner · Denver area
Where we work

What areas do you cover for furnace repair?

Atlas Mechanical covers the south Denver metro plus the north and west side — Lone Tree, Highlands Ranch, Castle Rock, Parker, Centennial, Littleton, Denver, Aurora, Lakewood, Arvada, Golden, Evergreen and the surrounding communities listed below. That includes Lone Tree, Parker and Castle Rock neighborhoods like Carriage Club, Heritage Hills, Meridian and Castlewood. We are based in Lone Tree and out across the metro daily. If you are close by, call or text (303) 601-1444 and we will get you scheduled.

Lone Tree Highlands Ranch Castle Rock Castle Pines Parker Centennial Littleton Englewood Greenwood Village Denver Aurora Lakewood Westminster Thornton Broomfield Arvada Commerce City Golden Genesee Evergreen Indian Hills
Ready when you are

No heat? Let's get it running again.

Call or text and you reach the technician who does the work. Same-day service when the schedule allows, and a flat-rate price before anything starts.

Furnace questions

What homeowners ask us about heat.

My furnace turns on then shuts off after a minute. What causes that?
That pattern is called short cycling and the most common cause is a dirty flame sensor, which stops proving the flame and shuts the burners down as a safety response. Other causes are a clogged filter restricting airflow, a failing limit switch, or a blocked flue. A flame sensor clean or replacement is usually an inexpensive same-visit repair.
Why does my furnace blow cold air?
If the blower runs but the air is cold, the burners are not staying lit or are not igniting at all. Common causes are a cracked igniter, a dirty flame sensor, a gas valve issue, or a tripped high limit. If the thermostat fan setting is on ON rather than AUTO, the blower simply runs between heating cycles, which also feels cold at the vent.
Is a cracked heat exchanger really dangerous, or is that a sales tactic?
It is genuinely dangerous, because a cracked heat exchanger can put combustion gases including carbon monoxide into the air you breathe. It is also one of the most abused claims in this trade. We show you what we found and why we reached that conclusion, and we would rather you get a second opinion than take our word for a replacement that size.
Should I repair or replace my furnace?
If the unit is under roughly 15 years old and the failure is an igniter, flame sensor, blower motor, inducer or control board, repair almost always makes sense. Past 15 to 20 years, or with a failed heat exchanger, replacement usually costs less over the remaining life than a series of repairs. You get both numbers and you decide, not us.
Do furnaces need to be set up differently at Colorado altitude?
Yes. Gas appliances have to be derated for altitude, which means the burner orifices and gas pressure are set for the thinner air at Front Range elevation. A furnace left at factory sea-level settings runs inefficiently and can soot up. We check and set this on every install and on repairs where it looks wrong.
How fast can you get out when the heat is off?
Often the same day when the schedule allows. Call or text (303) 601-1444 early in the day for the best chance at a same-day slot. We answer until 9 PM, seven days a week.

Cooling season question instead? See AC repair, or everything we do.

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