Boiler Repair in Lone Tree & South Denver

What we actually find

Why is my boiler not heating, or one zone cold?

Most boiler and radiant-heat calls in the south Denver metro come down to one of six things, and several of them are small parts once you know which one you are looking at. Knowing the difference is how a repairable boiler avoids being sold as a replacement.

Usually the pump

No heat, radiators cold

The circulator pump is the single most common failure on a hydronic system. It seizes or the motor quits, the boiler may even fire, but nothing moves the hot water. Sometimes you can hear a stuck pump hum. Replacement is routine for a shop that actually stocks hydronic parts.

Air in the loop

One zone or room stays cold

Air trapped in the loop, a zone valve that stopped opening, or a zone circulator down. The classic tell is one cold room while another cooks. Bleeding the air or repairing the valve usually brings the zone back the same visit.

Pressure

Gauge low, or creeping up

Low pressure means the system has lost water through a slow leak or a fill valve issue. Pressure that climbs until the relief valve drips is the signature of a waterlogged expansion tank. Both are diagnosable in minutes with the right eyes on the gauge.

Noise

Banging, gurgling or kettling

Kettling is scale on the heat exchanger making water boil where it should flow, a rumble like an oversized kettle. Gurgling is air moving through the loop. Ticking in baseboard fins is often harmless expansion. We tell you which one you have before anything gets replaced.

Leaks

Water around the boiler

Relief valve discharge, a weeping pump flange, a fitting on the return: the source decides the fix. Chasing a leak by throwing parts at it is how bills grow, so we find where the water actually starts before anything comes apart.

Honest answer

Old boiler, repeat repairs

Cast iron runs for decades, and plenty of 30-year boilers are worth keeping. When the heat exchanger goes, or an inefficient unit keeps eating parts, replacement can win on the math. You get the repair number and the replacement number side by side, and you decide.

Tell us what yours is doing

Hydronic heat, done right

Do you actually specialize in boilers?

Yes. Boilers and radiant heat are a core service at Atlas, not a sideline. A large share of metro shops only work on forced air and quietly decline hydronic calls, which leaves boiler owners ringing down a list. This is work we know cold: circulator pumps, zone valves, expansion tanks, radiant loops, baseboard and conventional radiators.

Gas boilers also have to be derated for Colorado altitude, exactly like furnaces. Left on sea-level factory settings the burner runs rich, wastes gas and soots the heat exchanger over time. We set combustion for the air the boiler is actually breathing.

And boiler work is genuinely year-round. Heating season is when repairs cannot wait, but the warm months are when replacements, re-pipes and maintenance happen on your schedule instead of during an outage. If your boiler limped through last winter, summer is the time to deal with it.

Pumps, valves & expansion tanksThe common hydronic failures, diagnosed correctly and repaired the same visit where parts allow.

Radiant & in-floor heatLoop, manifold and mixing issues on radiant systems, the calls most shops pass on.

Flat-rate price before any workYou approve the number first. No hourly meter, no finding out the cost once it is apart.

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 73 reviews — boiler repair shows up in them by name. 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

Read all reviews on Google

Where we work

What areas do you cover for boiler 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

Boiler questions

What homeowners ask us about boilers.

My boiler runs but one zone never gets warm. What is wrong?

On a hydronic system a cold zone usually means air trapped in that loop, a zone valve that is not opening, or a circulator pump that has quit for that zone. Bleeding the loop or repairing the valve is a normal same-visit fix. It is a different diagnosis than a forced-air cold room, which is why boiler experience matters.

Why is my boiler making a banging or rumbling noise?

A rumble or bang from the boiler itself is usually kettling: mineral scale on the heat exchanger making water boil locally instead of flowing through. Gurgling in the pipes is trapped air. Ticking in baseboard fins as heat comes up is often just expansion. Kettling and trapped air are both fixable, and both get worse if ignored.

What pressure should my boiler be at?

Most residential systems sit around 12 to 15 psi cold and rise a few psi when hot. If the gauge keeps climbing until the relief valve drips, the expansion tank has usually failed. If it reads near zero, the system has lost water and the fill valve or a leak needs attention. Either way it is diagnosable, not guesswork.

Should I repair or replace my boiler?

Cast-iron boilers regularly run 25 to 40 years, so age alone is not a verdict. Pumps, zone valves, expansion tanks and gas components are all replaceable. When the heat exchanger itself fails, or repairs start stacking on an inefficient unit, replacement can win on the math. You get both numbers before you decide, not a pitch.

Do boilers need to be set up for Colorado altitude?

Yes, exactly like furnaces. Gas combustion has to be derated for the thinner air at Front Range elevation or the boiler runs rich, wastes gas and soots up. We set it on every install and check it on repairs where the burner looks wrong.

Do you work on radiant floor heat and baseboard systems?

Yes. Radiant in-floor loops, baseboard hydronic and conventional radiators are all systems we diagnose and repair, and much of the metro will not touch them. Often same-day when the schedule allows. Call or text (303) 601-1444 and we answer until 9 PM, seven days a week.

Forced-air question instead? See furnace repair, AC repair, or everything we do.

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