Boiler Repair, Installation & Replacement Across the Denver Metro

Boiler Repair & Installation in Denver

Deft Plumbing repairs, installs, and replaces residential gas boilers across the Denver metro, with a flat-rate number in writing before we touch anything. We diagnose the actual fault first instead of quoting a new boiler on sight, and we handle the two things that trip up Front Range boiler work: the altitude-derated BTU setup manufacturers require above roughly 5,300 feet, and the gas-line permit and pressure test any new supply run triggers with the city.

Your boiler quit and the house is getting cold, or it's limping along and you're deciding whether to fix it or replace it. That's the reason you're here. We're a licensed, bonded, and insured Colorado plumbing contractor. On a boiler, diagnose-first isn't a slogan. A cold radiator can be a stuck circulator, a waterlogged expansion tank, an air-locked zone, a bad zone valve, or a failed ignition board, and each one carries a completely different repair. We test the system and tell you which it is instead of quoting a whole new boiler on sight. If a targeted repair will hold, that's the quote you get. Call (720) 880-8064 if you have no heat right now.

Boiler Repair in Aurora and Across the Denver Metro

Most boiler repairs in the metro come down to one of five faults, and we test for all of them before quoting. A stuck circulator pump, a waterlogged expansion tank, an air-locked zone, a failed zone valve, or a dead ignition control. We diagnose the actual fault first. We do not quote a replacement boiler on a symptom that an inexpensive part fixes.

Aurora sits at roughly 5,300 feet, and that altitude changes how a gas boiler burns. Manufacturers require BTU input to be derated about 4 percent for every 1,000 feet above sea level, which means a boiler set up to a national-average spec runs rich here. Rich combustion wastes fuel, sooties the heat exchanger, and pushes carbon monoxide higher than it should be. When we service a boiler, we confirm the altitude orifice and the input rating are correct for your elevation, not just that the unit fires.

Front Range fact

Above ~5,300 ft, gas boilers need an altitude kit and a derated BTU input. A unit set to sea-level spec runs rich, wastes gas, and raises CO. We verify this on every boiler we touch.

The failure that lands as an after-hours call almost every time is a circulator or zone valve giving out in the first hard cold snap of the season. The system ran fine in October, then the first sustained sub-20°F stretch loads it up and the weak component drops. If your boiler fires but a whole floor or zone stays cold, that's usually a circulator or a zone valve, not the boiler itself. Aurora homeowners can read our full Aurora boiler repair and installation guide for what the altitude derate and permit steps look like locally, or talk to a licensed tech now: (720) 880-8064.

Boiler Not Firing or No Heat: Troubleshooting Before You Call

Before you call anyone, there are three safe checks that fix a surprising number of no-heat calls. None of them involve opening the boiler or touching the gas.

1. **Check the thermostat and its batteries.** A dead thermostat battery or a thermostat bumped off "heat" is the single most common no-heat cause. Swap the batteries and confirm the mode and setpoint before anything else.
2. **Check the boiler's power switch and breaker.** Most boilers have a red service switch on or near the unit that looks like a light switch. If it got flipped, the boiler has no power. Check that switch and the breaker in the panel.
3. **Read the boiler's pressure gauge.** A cold-system reading should sit around 12 to 15 psi. If it's near zero, the system has lost water and locked out. That's a real fault, not a reset, and it needs a tech.

If the boiler locks out again within minutes of a reset, stop resetting it

Repeated lockouts are a safety control doing its job. Something upstream is wrong and forcing it clear can make the fault worse.

If none of that brings the heat back, the fault is inside the system: ignition control, gas valve, low water, a failed high-limit, or a stuck circulator. Those are not homeowner fixes. When you have no heat and a house full of pipes in a Colorado winter, that's a same-day call for us. We run emergency boiler repair with parts on the truck, and we give you a flat-rate number before the work starts. Get a free quote or call (720) 880-8064.

When Boiler Replacement Beats Another Repair (and the Warning Signs)

We don't default to replacement. A new boiler is a real expense, and we won't tell you to buy one unless the numbers say so. Here's the honest framework.

Repair almost always wins when the boiler is under about 12 years old and the fault is a single component. Circulators, zone valves, expansion tanks, ignition boards, and pressure relief valves are parts, not the boiler. Swapping one is a fraction of a replacement, and the heat exchanger still has years left.

Replacement starts to win when you hit these signs:

• The cast-iron or steel heat exchanger is leaking (water pooling under the boiler that isn't from a relief valve or a fitting)
• Efficiency has fallen off a cliff and gas bills climbed with no change in the weather
• The unit is 15-plus years old and a major part (heat exchanger, gas valve, control board) has failed
• It short-cycles constantly and no repair has held
• You're getting repeat no-heat calls every winter on the same aging unit

The math we use

If a major repair on a 15-year-old boiler runs 40 percent or more of a replacement, replacement usually wins. A new boiler carries a warranty and modern efficiency. A repaired old one carries its age. We break down how we weigh fixing a boiler against replacing it in more detail, with the specific age and cost thresholds we use.

When replacement is the call, we size the new boiler to your home's actual heat load and derate the BTU input for your elevation, then we pull the permit and coordinate the inspection. Any new gas run gets a pressure test. Ready when you are: (720) 880-8064.

Boiler Installation in Aurora: What a Correct Install Includes

A boiler install is not a swap-in-whatever-was-there job, and the difference shows up in the first cold winter after. Here's what a correct Denver-metro boiler installation includes, and what we do on every one.

We start with a heat-load calculation, not a nameplate match. Boilers get oversized constantly because someone read the old unit's rating instead of the home's actual demand. An oversized boiler short-cycles, which wastes fuel and wears the ignition and pump faster. We size to the load.

Altitude derate and gas supply, verified before startup

At Aurora's ~5,300-foot elevation, the new boiler gets its BTU input derated to spec and, where the manufacturer requires it, an altitude kit or orifice installed. We also confirm the gas supply line can carry the boiler's full BTU draw. A boiler starved by an undersized gas line underperforms and faults, and it's an infrastructure problem, not a defect. Because gas boilers need a code-compliant, pressure-tested gas supply, any new run we make is installed and pressure-tested to code before the boiler ever fires.

Expansion control, permit, and inspection

On a closed-loop hydronic system, code requires thermal expansion control. We confirm the expansion tank is correctly sized and charged, not just present. We pull the permit, run the required pressure test on any new gas piping, and coordinate the city or county inspection ourselves. In Adams County and across the metro, that inspection schedule is the city's, not ours, so we don't promise same-day completion on permit-required work. What we promise is that the permit gets pulled and the inspection gets scheduled, both included in the flat-rate quote. Tell us what's going on and we'll come back with a flat-rate number.

Combi Boiler vs. System Boiler: Which Fits a Denver Home

The choice between a combi boiler and a system boiler comes down to how your home makes hot water, and there's no universal right answer. We spec to the household, not to a preference.

A combi boiler makes heat and domestic hot water from one unit, on demand, with no separate tank. It saves space and works well for smaller homes and lower simultaneous hot-water demand. The tradeoff is that heavy simultaneous draws (two showers plus a dishwasher) can outrun a single combi, and at altitude the derated BTU output eats into the margin that a combi needs to serve both jobs at once. Our breakdown of combi versus system boilers for a Denver home walks through how household size and altitude tip that decision.

A system boiler heats the home and feeds a separate hot-water storage tank (often an indirect tank). It handles higher simultaneous demand better and pairs naturally with larger households and multiple bathrooms. It needs the space for the tank, but it doesn't get squeezed the way a combi can when heat and hot water are both called at once.

Not sure a boiler is even the right call?

If your home uses forced-air heat and you only need to solve hot water, compare a boiler to a water heater replacement first. We'll tell you honestly which one your house actually needs.

We won't push a combi into a home whose gas supply or hot-water demand doesn't fit it, the same way we won't push a tankless water heater onto a gas line that can't carry it. We calculate demand, check the gas supply, factor in the altitude derate, and then recommend the configuration that fits. Call (720) 880-8064 and we'll walk through it.

When a Boiler Isn't the Right Call

Not every no-heat house needs boiler work, and we'd rather tell you that up front than sell you a service call you don't need.

Don't call us for a boiler repair if your home is heated by a forced-air furnace

A furnace and a boiler are different systems, and "no heat" from a furnace is a different trade and a different diagnosis. If you have supply registers blowing air rather than radiators or baseboard, you have a furnace, and we'll point you the right direction rather than roll a truck.

Don't replace a boiler on age alone

A 14-year-old boiler that heats evenly, holds pressure, and passes a combustion check has years of service left. Age is a factor in the replace-versus-repair math, it is not a verdict by itself. If a contractor quotes you a full replacement without testing the circulator, the expansion tank, and the ignition, get a second opinion.

And if your boiler is under warranty on a part that just failed, check the warranty before you pay for a replacement component out of pocket. We'll help you read it. That's the diagnose-first, quote-the-total approach the whole business runs on, and it doesn't change just because it's a boiler.

Gas Boiler Brands We Repair: Navien, Viessmann, and More

We diagnose and repair the common residential gas boiler brands running across the Front Range, and the brand on the jacket doesn't change the method. We test the actual fault first, then quote a flat-rate number in writing. We are not naming ourselves an authorized dealer for any manufacturer. We are telling you which units we work on and how we approach each one.

Navien combi and system units show up constantly in newer Denver-metro builds and in tankless-to-hydronic setups. When a Navien throws a fault code, the common causes we chase are a clogged or scaled heat exchanger, a dirty flame sensor, a failed igniter, or a gas supply that can't feed the modulating burner at full fire. At altitude that last one bites hard, because a modulating boiler needs the full BTU draw and an undersized branch line starves it into a nuisance lockout.

Front Range fact

Denver Water runs 12 to 17 grains per gallon. That hardness scales a boiler's heat exchanger and the internal hot-water passages on a combi, which is why a Navien or Viessmann combi in this water benefits from a service flush more often than the manual's sea-level schedule suggests.

Viessmann boilers, especially the stainless heat-exchanger condensing models, are common in higher-efficiency retrofits around the metro. The faults we see are different: condensate drain blockages, ignition and flame-rod issues, and pressure-sensor faults. On any condensing boiler we also check that the condensate is draining and neutralizing correctly, because a plugged condensate trap will lock out a Viessmann just as fast as a bad igniter.

We diagnose first, whatever the brand

Before we quote a part on a Navien, a Viessmann, or any other residential gas boiler, we confirm the fault with a live test. A cold zone on a branded combi can still be a stuck circulator, an air-locked loop, or a bad zone valve, exactly the same five faults we test for on every boiler. The brand narrows the parts list. It doesn't change diagnose-first.

Not sure what brand you have or what the fault code means? Talk to a licensed tech and we'll walk it through: (720) 880-8064.

Central Heating and Hydronic Heat Repair

If your house heats with radiators, baseboard, or in-floor loops rather than forced air, you have hydronic central heating, and the boiler is only one part of it. Central heating repair on a hydronic system means diagnosing the whole loop, not just the box in the mechanical room. We test the boiler, the circulator pumps, the zone valves, the expansion tank, and the fill and pressure controls, then tell you which one actually failed.

The single most common central heating complaint we get is uneven heat: one zone or one floor stays cold while the rest of the house heats fine. That is almost never the boiler. It's usually a stuck circulator, an air-locked zone, or a failed zone valve, and each is a targeted repair, not a reason to replace the heating system.

• One zone cold, rest of house fine: usually a dead circulator, a failed zone valve, or trapped air in that loop
• Whole system cold, boiler firing: often a circulation fault or a waterlogged expansion tank
• System won't hold pressure: a leak in the loop, a failed fill valve, or a spent expansion tank
• Banging or knocking in the pipes: air in the system or a circulator mounted or sized wrong

A cold radiator is a diagnosis, not a verdict

We bleed the zone, test the circulator, and check the zone valve before anyone talks about a new boiler. The five faults we test for on a no-heat boiler are the same ones behind a single cold zone, so we prove which one it is before quoting a part.

Front Range hydronic systems take a specific beating. The freeze-thaw swing between single-digit nights and 50-degree afternoons cycles the whole loop hard, and the older gas-heat housing stock in neighborhoods like Original Aurora, Old Town Arvada, and downtown Brighton runs boilers that are on their second or third decade. We diagnose the fault, quote the flat-rate total in writing, and never sell a whole new system to fix one cold zone. Ready when you are: (720) 880-8064.

Converting an Oil Boiler to Gas

Plenty of older Front Range homes still run an oil-fired boiler, and if you have natural gas at the street, converting to a gas boiler is a real project we handle end to end. The heating side is a boiler swap. The part that trips up a lot of contractors is the fuel side, and that's exactly the work Deft does day in and day out: we install natural gas piping, pull the gas permit, and pressure-test the line before anything is lit.

A correct oil-to-gas conversion is engineered on both sides at once. We size the new gas boiler to your home's actual heat load and derate the BTU input for your elevation, then we run and size the gas supply to carry that full input with every other appliance on the branch firing at maximum.

Why the gas line matters on a conversion

A boiler starved by an undersized branch line nuisance-locks all winter. On a conversion there was no gas run to the boiler before, so the supply gets sized and permitted from scratch, not spliced onto whatever fed the old oil burner.

Any new gas run to the converted boiler is permitted, pressure-tested, and inspected work. We pull the permit, run and support black iron or CSST to code, install a sediment trap and an accessible shutoff at the appliance, then stand a pressure test on the line and soap-bubble every joint before the boiler fires. The details of that fuel-side work are the same ones we cover on our natural gas piping page, sized and pressure-tested to code.

One flat-rate quote, both sides of the job

The whole conversion runs on one flat-rate quote that covers the boiler, the gas piping, the permit, the inspection coordination, and haul-away of the old oil unit. You know the total before we touch anything. Tell us what's going on and we'll come back with a flat-rate number, or call (720) 880-8064.

Need Boiler Repair & Installation?

Contact Deft Plumbing for a free, upfront quote. No surprises, no hidden fees. We're licensed, bonded, and insured for your protection.

Call (720) 880-8064 or request a free estimate online.

Related Services

Service Areas

We provide boiler repair & installation services across the Denver metro area, including Aurora, Lakewood, Arvada, Westminster, Thornton, Broomfield, and more.

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