Services
Everything that heats, cools, or cleans the air in your home.
Five services, every brand, every install sized for a mile of altitude. Three things cost $99. Everything else gets a written price before we start.
- $99 diagnostic
- $99 tune-up
- $99 air quality check
Type what’s happening or what you want, in your own words.
188 answers
- Repair Furnace blowing cold airFour causes, one you can fix yourself
- Repair No heat at allSame-day, front of the line
- Repair Furnace won’t turn onSame-day, 24 hours
- Repair Furnace short cyclingOverheating or oversized
- Repair Furnace runs constantlyThermostat, leaks, or undersized
- Repair Furnace keeps clickingUsually the igniter
- Repair Furnace lights then shuts offFlame sensor, most often
- Repair Pilot light outIgniter and gas valve repairs
- Repair Yellow or flickering flameShut it off and call
- Repair Furnace blower won’t stopOften the fan switch set to ON
- Repair Furnace blower not runningMotor, capacitor, or board
- Repair Heat comes on lateDelayed ignition or airflow
- Repair Furnace tripping breakerStop resetting it. Call
- Repair Furnace limit switchAirflow first, then the part
- Repair Flame sensorA quick cleaning, first visit
- Repair Hot surface igniterCommon, usually on the truck
- Repair Cracked heat exchangerWe show you the crack on camera
- Repair Furnace pressure switchVenting first, then the switch
- Repair Furnace control boardThe light tells us a lot
- Info Furnace filterCheck monthly, change as needed
- Repair Furnace smells like gasLeave first. Xcel, then us
- Repair Burning smell from ventsA minute is normal. Longer, call
- Repair Musty smell from ventsCoil, drain, or ducts
- Repair Furnace humming but not startingCapacitor or motor
- Info Old furnaceKnow what to expect, no pressure
- Info Furnace at altitudeWhat a mile of altitude changes
- Repair Wall furnaceWe know the old ones
- Repair Electric furnaceRepair, or a heat pump upgrade
- Repair Gas valveTested, then written up
- Repair Furnace ventingSnow and nests block it
- Repair AC not coolingSame-day, $99 diagnostic
- Repair No AC at allSame-day, front of the line
- Repair AC frozenTurn it off first, then call
- Repair AC runs all dayUndersized, leaky, or losing capacity
- Repair Outdoor unit won’t startCapacitor or contactor, often
- Repair AC fan not spinningDon’t push it with a stick. Call
- Repair AC capacitorA quick, common part
- Repair AC contactorFast when caught early
- Repair Refrigerant leakFind the leak, then recharge
- Repair AC short cyclingOversized or a failing part
- Repair AC tripping breakerCompressor or wiring. Call
- Repair AC buzzing or grindingShut it down to avoid a bigger bill
- Repair AC leaking waterUsually the drain line
- Repair AC smellsCoil and drain cleaning
- Repair CompressorBoth numbers, then you decide
- Repair Evaporator coilRepair, or the whole picture
- Repair Condenser coil cleaningPart of the $99 tune-up
- Repair Hail damage to ACCombed straight, usually
- Info Old ACKnow what to expect, no pressure
- Install Replace a swamp cooler with ACWe install the AC or heat pump
- Install Window AC alternativeA mini split does it quietly
- Install AC for a house with no ductsMini splits, no ducts needed
- Info AC ready for summerSeven ten-minute jobs
- Repair Rooms hot and coldDucts, zoning, or a mini split
- Repair Upstairs too hot in summerZoning or a second return
- Repair Basement too coldBalancing or a mini split
- Repair Drafty houseDuct leaks, mostly
- Repair Weak airflowFilter, blower, or ducts
- Repair Vents not blowing in one roomDamper, duct, or a disconnect
- Info Dry airWhy Denver homes need a humidifier
- Repair Too humidDehumidifier or AC fix
- Install Wildfire smoke indoorsMERV-13 or HEPA catches it
- Repair Dust everywhereLeaky returns pull it in
- Install Allergies at homeFiltration, UV, purifiers
- Install Stuffy new homeAn ERV brings fresh air in
- Repair Mold around ventsHumidity and ducts, checked
- Price Air quality test$99, measured and written up
- Repair Carbon monoxide alarmGet outside, then call
- Info CO detector placementEvery level, near bedrooms
- Repair Headaches when the heat runsGet outside and call now
- Repair Furnace making noiseMatch the sound to the cause
- Repair Banging when the furnace startsDelayed ignition. Fixable
- Repair RattlingLoose panel or duct, usually
- Repair Squealing or screechingA motor or belt
- Repair Whistling ventsAirflow starved somewhere
- Info Ductwork poppingExpanding ducts. Usually harmless
- Repair GrindingShut it off and call
- Repair Humming outsideCapacitor, often
- Repair Thermostat blankOften batteries or a float switch
- Repair Thermostat says heat but no heatWiring, fuse, or the furnace
- Repair Thermostat reads wrongPlacement or sensor
- Install Smart thermostatInstalled in under an hour
- Info Thermostat scheduleA schedule that fits Denver
- Install C-wireWe add one when needed
- Install Thermostat for a heat pumpThe right one matters
- Repair Blown low-voltage fuseA fuse and a wiring check
- Repair Float switchClear the drain, reset it
- Repair Water leaking from furnaceUsually the AC drain
- Repair Condensate drain cloggedA quick clearing
- Repair Condensate pumpCommon on high-efficiency units
- Repair Drain pan crackedA new pan
- Repair Humidifier leakingPad, valve, or drain
- Repair Furnace repairEvery brand, same-day
- Install Furnace replacementHigh-efficiency, set for altitude
- Install High-efficiency furnaceUp to 99% efficient
- Install Low-NOx furnaceCleaner burning, best rebates
- Repair AC repairSame-day, $99 diagnostic
- Install AC installationDone in a day, permit pulled
- Install Furnace and AC togetherOne estimate, both options
- Install Heat pumpXcel rebates filed for you
- Info Heat pumps in ColoradoWhat works below zero
- Install Mini splitBasements, garages, additions
- Install Mini split heatingRooms without ducts, year-round
- Install Mini split for a garageOne head, year-round
- Install Heat for an additionExtend ducts or a mini split
- Install HumidifierDenver winters need one
- Install DehumidifierFor the damp basement
- Install Air purifierSmoke, allergies, asthma
- Install Air filter upgradeCatch wildfire smoke
- Install UV lightCuts mold on the coil
- Repair Duct sealingBiggest win in older homes
- Info Duct cleaningOnly when it’s actually dirty
- Install Adding a return ventA modest job, big payoff
- Install New ductworkSized for the house, not the box
- Install ZoningEach floor gets its own control
- Install Energy recovery ventilatorFor tight new homes
- Info Attic fanAsk. We’ll say if it helps
- Info ENERGY STAR equipmentWhat unlocks most rebates
- Install Energy efficiency upgradeWalkthrough with every estimate
- Repair Rooftop unitTownhomes and condos included
- Repair Condo or townhome HVACCloset and rooftop systems
- Info Mobile home furnaceAsk. Send the form
- Price Diagnostic fee$99, credited toward the repair
- Price Tune-up$99
- Info What a tune-up includesThe full list
- Price Furnace repair costHow pricing works, in writing
- Price Furnace replacement costFree written estimate, rebates applied
- Price AC replacement costFree written estimate, rebates applied
- Price Free estimateNo pressure, in writing
- Price Second opinionFree, honest, in writing
- Info Repair or replaceKnow what to expect
- Price Xcel Energy rebatesWe file them for you
- Price Colorado heat pump tax creditDocuments provided
- Price FinancingApproval in minutes
- Price Maintenance planTwo tune-ups, no overtime fees
- Price Forms of paymentAll of them
- Price No overtime feesNights and weekends cost the same
- Price Written priceBefore any work, every time
- Info WarrantyRegistered before we leave
- Info Home warranty companyUse us and still get reimbursed
- Info Insurance claimWe document it for you
- Info Invoice or receiptEmail us, same day
- Repair 24/7 emergencyNo overtime fees
- Info How fast can you get hereSame-day across the metro
- Info Book onlineAbout 30 seconds
- Info Phone number(720) 447-0177, call or text
- Info Licensed and insuredLicensed, bonded, insured
- Info Who shows upThe owner, a licensed tech
- Info Service areaGolden to Aurora and beyond
- Info DenverOur home turf
- Info LakewoodAbout 20 minutes
- Info AuroraAbout 25 minutes
- Info EnglewoodOur shop is here
- Info LittletonAbout 12 minutes
- Info ArvadaAbout 30 minutes
- Info WestminsterAbout 30 minutes
- Info ThorntonAbout 35 minutes
- Info CentennialAbout 12 minutes
- Info Highlands RanchAbout 15 minutes
- Info Wheat RidgeAbout 20 minutes
- Info GoldenAbout 30 minutes
- Info Castle RockAbout 30 minutes
- Info Reviews5.0 on Google
- Info Brands you serviceAll of them
- Info Landlord serviceOne plan, every address
- Info Selling a houseA written report for the file
- Info Buying a houseScore it, then book the real look
- Info Comfort CheckScore your system in a minute
- Info Seasonal remindersFree, by email or calendar
- Info Free toolsNo email, no account
- Info Compared to the big companiesSide by side, honestly
- Info Do it myselfWhat’s safe, what isn’t
- Info PermitsPulled on every install
- Info Boot covers and cleanupCleaner than we found it
- Info Arrival windowA two-hour window and a text
- Info SpanishCall or text and ask
- Info Fall checklistWhat to do before the first freeze
- Info First freezeTest the heat before you need it
- Repair Frozen pipesNo heat below freezing: call now
- Info Going on vacationWhat to set it to
- Info Power outage resetSwitch, breaker, then call
- Info Snow on the furnace ventClear it, then test the heat
- Repair Heat waveFront of the line over 85° inside
- Install Smoke seasonFilters that actually catch it
- Price Spring AC check$99, before the first hot week
- Price Fall furnace tune-up$99, before the first freeze
- Info How often to change the filterCheck monthly, change as needed
- Info What to do while you waitThe quick checks, by problem
-
Furnace repair, replacement, and $99 tune-ups. Same-day, any brand, sized for Denver altitude.
- Furnace repair on every brand, same-day across the metro
- High-efficiency and Low-NOx furnace installation, derated for Denver altitude
- Mini split heating for rooms without ducts
Learn more about Heating $99 furnace diagnostic -
AC repair and new systems, heat pumps, and mini splits. Fast dispatch when it quits on a hot day.
- Air conditioner repair on every brand
- New central AC and cold-climate heat pump installation
- Ductless mini splits for additions and homes without ducts
Learn more about Cooling $99 ac diagnostic -
Humidifiers, filtration, purifiers, and duct sealing. Breathe easier through dry winters and smoke season.
- $99 indoor air quality assessment (particles, humidity, pollutants) with a written report
- Whole-home humidifiers and dehumidifiers
- Media filtration and HEPA upgrades
Learn more about Indoor Air Quality $99 air quality assessment -
Low-NOx furnaces, cold-climate heat pumps, ENERGY STAR equipment. We file your Xcel rebates.
- Low-NOx, high-efficiency furnace installation
- Cold-climate and dual-fuel heat pump systems
- Ductless mini-split installation, single and multi-zone
-
Two tune-ups a year, priority scheduling, and no surprise breakdowns. The cheapest HVAC decision you’ll make.
- Two tune-ups per year, heating and cooling
- Priority same-day scheduling
- Discount on all repairs and air quality products
- Get emergency help
No heat? No AC?
24/7 emergency repair. No overtime fees.
A Denver dispatcher answers day or night and a truck is on the way in hours, not days.
Which door are you at?
Fix it. Replace it. Protect it.
Whichever one you pick, the rest is the same: written price, same-day, a neighbor who answers.
Not ready to book? Each door has a free tool. No email, no account.
-
Fix it
Something’s broken. We find it for $99, write the price, and usually fix it the same visit.
Get it fixed -
Replace it
It’s old, loud, or expensive to run. A free estimate shows repair next to replace, with rebates applied.
Get an estimate -
Protect it
Nothing’s wrong yet. A $99 tune-up or a Comfort Plan keeps it that way through the season.
Book a tune-up
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.
Proof you can check
No anonymous quotes. Nothing you have to take our word for.
Every claim on this site points at something you can verify yourself. Here are the four that matter most.
-
5.0 on Google
12 public reviews. Read every word, including the owner's replies.
Open Google -
License lookup
Colorado publishes every contractor license. Search the state registry yourself.
Check DORA -
A real address
3940 S Hazel Ct, Englewood, CO 80110. Not a P.O. box, not a call center.
See the map -
Ask a neighbor
References on request: a real Denver homeowner on the phone, not a scripted case study.
Request one
- 5.0 12 Google reviews, all five stars ↗
- NATE CertifiedNorth American Technician Excellence
- BBB A+ RatingBetter Business Bureau
- LENNOX We service
Lennox systems - We service
Trane systems
Ready When You Are
Tell Us What's Wrong. We'll Call You Back in Minutes.
Three quick taps. A real Denver dispatcher calls to confirm your address and get a truck moving. No call center, no waiting on hold.
- Written flat-rate price before any work starts
- Same-day service across the Denver metro
- No overtime fees, nights and weekends included
Prefer to talk? (720) 447-0177, open 24 hours.