Furnace repair in Denver costs $150–$600 for most common issues. A failed ignitor, dirty flame sensor, or faulty blower motor can leave you without heat overnight in a city where November lows hit 20°F. Here is what each repair costs, which problems you can wait on, and which ones need a call today.
Emergency service available 24/7: If your furnace is not producing heat, do not wait. Call (303) 414-7770 for same-day service in Denver and the surrounding metro area.
Furnace Repair Costs in Denver (2026)
Costs below are for parts and labor from a licensed HVAC technician in the Denver metro area. Prices vary by furnace brand, age, and accessibility.
| Repair Type | Typical Cost | Notes |
|---|---|---|
| Ignitor replacement | $150 – $250 | Most common furnace repair in Denver; usually same-day fix |
| Flame sensor cleaning | $80 – $150 | Dirty sensors cause short-cycling; often caught at annual tune-up |
| Blower motor replacement | $300 – $600 | Signs: no airflow or loud rumbling; higher end for variable-speed motors |
| Control board replacement | $300 – $650 | Fails after power surges; controls all furnace functions |
| Heat exchanger repair | $500 – $1,500+ | Cracked exchangers leak CO; often leads to full replacement recommendation |
| Draft inducer motor | $250 – $500 | Failure causes furnace to shut off before igniting |
| Gas valve replacement | $200 – $600 | Rare but critical; furnace produces no heat when valve fails |
| Flue/venting repair | $150 – $400 | Denver altitude requires proper venting; blockages cause safety shutoffs |
Rule of thumb: If the repair costs more than 50% of a new furnace installed, or your unit is over 15 years old, replacement usually makes more financial sense. We cover this in detail below.
6 Most Common Furnace Problems in Denver
1. Furnace not turning on
Usually a failed ignitor or tripped safety switch. The ignitor glows red to light the burners — over time it burns out. Cost: $150–$250 to replace. Diagnosis and fix typically same day.
2. Furnace short-cycling (turns on and off repeatedly)
Most often a dirty flame sensor or overheating caused by a clogged filter. A dirty sensor cannot confirm the burner is lit and shuts the furnace off as a safety measure. Cost: $80–$150 for sensor cleaning. Replace your filter first — if that does not fix it, call.
3. No airflow or weak airflow
A failing blower motor or blocked ductwork. In Denver homes with ducted systems, restricted airflow raises heat exchanger temperatures and triggers safety shutoffs. Cost: $300–$600 for blower motor replacement.
4. Furnace runs but no heat
A closed gas valve, failed control board, or cracked heat exchanger. A cracked heat exchanger is the most serious — it can allow carbon monoxide to enter living spaces. If your CO detector goes off, leave the house and call immediately.
5. Loud banging, rattling, or squealing
Banging on startup usually means delayed ignition (gas buildup lighting at once). Rattling can be loose panels or a failing inducer motor. Squealing is typically a blower belt or motor bearing. None of these should be ignored — they worsen quickly.
6. Furnace not reaching set temperature
Could be a dirty filter, failing thermostat, or an undersized unit. At Denver’s 5,280 feet, gas furnaces run at roughly 80% of sea-level efficiency. An older furnace already losing efficiency will struggle more in cold snaps.
Repair vs. Replace: When Does It Make Sense to Fix a Denver Furnace?
Use this framework to decide:
- Age under 10 years and repair under $400: repair almost always makes sense.
- Age 10–15 years and repair $300–$600: evaluate efficiency; a 15-year-old 80% AFUE furnace replaced with a 96% unit can cut heating bills 20%.
- Age over 15 years or repair over $700: replacement is usually the better investment.
- Cracked heat exchanger at any age: replace — repairing a cracked exchanger is rarely cost-effective and the safety risk is real.
Denver note: Homes built before 2000 often have 80% AFUE furnaces. Replacing with a 96% AFUE unit qualifies for Xcel Energy rebates of $75–$300 and may qualify for federal tax credits. Ask your technician.
What to Expect on a Furnace Repair Visit
- Diagnosis: the technician runs a full system check — combustion analysis, heat exchanger inspection, electrical and gas pressure tests — to confirm the root cause before any parts are ordered.
- Estimate: you receive a written repair cost before work begins. No surprises.
- Repair: most common repairs (ignitor, sensor, capacitor) are completed same visit. Aether trucks carry common parts for Denver’s most frequent furnace brands.
- Test and verify: the furnace is run through a full heating cycle, temperatures are confirmed at registers, and CO levels are checked before the technician leaves.
- Service record: all work is documented so future technicians have a complete repair history.
Furnace not working? Same-day service in Denver.
(303) 414-7770 · aethermechanical.com/contact
Frequently Asked Questions
How much does furnace repair cost in Denver?
Most furnace repairs in Denver cost $150–$600. Simple fixes like ignitor replacement or sensor cleaning are on the lower end. Blower motors, control boards, and draft inducer motors fall in the $300–$650 range. Heat exchanger issues can exceed $1,000 and often lead to a replacement recommendation.
How long does a furnace repair take?
Most common repairs are completed in 1–2 hours. If a part needs to be ordered, expect 1–3 business days. Aether carries common parts on every truck to complete same-day repairs whenever possible.
Is it safe to run my furnace if it is making a banging noise?
A single bang on startup (delayed ignition) should be checked soon but is not an immediate emergency. Continuous banging or a bang followed by no heat: shut the furnace off and call. Delayed ignition left unaddressed can cause more serious damage.
Does Aether offer emergency furnace repair in Denver?
Yes. Aether provides 24/7 emergency HVAC service in Denver and the surrounding metro area. Call (303) 414-7770 for after-hours dispatch.
How do I know if my heat exchanger is cracked?
Signs include a CO detector alarm, a yellow or flickering flame (should be steady blue), soot near the furnace, or unusual odors when the heat runs. A cracked heat exchanger requires a technician inspection — do not try to diagnose it visually yourself.
Why does my furnace keep turning off?
Short-cycling is almost always a dirty flame sensor, overheating from a clogged filter, or a malfunctioning limit switch. Replace your filter first. If the problem continues, a technician can diagnose and fix it in a single visit.
