Quick Answer: Furnace replacement in Denver costs $3,500-$7,500 installed, depending on size, efficiency, and features. Entry-level 80% AFUE furnaces run $3,500-$5,000 for a 60,000-80,000 BTU unit. Mid-range 92-95% AFUE (high-efficiency) costs $4,500-$6,000. Premium 96-98% AFUE variable-speed systems reach $6,000-$7,500. At Denver’s 5,280-foot altitude, furnace sizing is critical – oversized units waste energy and short-cycle; undersized units run constantly during single-digit nights. Blue Collar Heating & Air has replaced hundreds of furnaces across Northglenn, Thornton, and Westminster – here’s exactly what you’ll pay and why.
What Determines Furnace Replacement Cost?
Furnace replacement cost breaks down into several factors:
Equipment Cost (55-65% of total)
- 80% AFUE: $1,800-$3,000 equipment only. Single-stage, basic warranty.
- 92-95% AFUE: $2,500-$4,000 equipment. Two-stage, variable-speed blower, 10-year warranty.
- 96-98% AFUE: $3,500-$5,000 equipment. Modulating gas valve, ultra-quiet, advanced diagnostics.
Labor & Installation (25-35% of total)
Professional installation runs $1,500-$2,500 and includes removal, mounting, gas/electrical connections, venting, testing, altitude adjustment, and permits.
Additional Costs
- Ductwork modifications: $500-$2,000
- Thermostat upgrade: $150-$400
- Gas line upgrades: $400-$1,200
- Humidifier: $400-$700
- Air purifier: $600-$1,500
Furnace Sizing for Denver Homes
Furnace installation: $3,500-$7,000 in Denver
Rule of thumb doesn’t work at altitude.
Sea-level: 40-45 BTU per sq ft
Denver: 35-40 BTU per sq ft (thinner air requires different calculation)
Common Denver furnace sizes:
- 1,000-1,400 sq ft: 40,000-60,000 BTU
- 1,400-1,800 sq ft: 60,000-80,000 BTU
- 1,800-2,400 sq ft: 80,000-100,000 BTU
- 2,400-3,000 sq ft: 100,000-120,000 BTU
80% vs. 95% Efficiency: Is It Worth It?
Short answer: Yes, if you’re staying 7+ years.
80% AFUE: $80 heats your home, $20 wasted. Denver winter bill: $180-$250/month. Vents through chimney. Lifespan: 15-18 years.
95% AFUE: $95 heats your home, $5 wasted. Denver winter bill: $140-$190/month. Requires PVC venting. Lifespan: 18-22 years.
Real savings: $40-$80/month × 4-5 months = $200-$400/year. Premium cost: $1,000-$1,500. Breakeven: 3-5 years.
Best Furnace Brands for Denver
Top tier:
- Carrier/Bryant: 92-98% AFUE, excellent parts availability
- Trane/American Standard: Durability, strong dealer network
- Lennox: Highest efficiency (98% AFUE), SunSource solar-ready
Mid-tier:
- Rheem/Ruud: Solid reliability, 10-year warranty
- York: Affordable, decent performance
Budget:
- Goodman/Amana: Entry pricing, improved quality
When to Replace vs. Repair
80% AFUE vs 96% AFUE – $300-500/year savings
$5,000 Rule: Age × Repair Cost
- 15 years old, $500 repair: 15 × $500 = $7,500 → Replace
- 8 years old, $400 repair: 8 × $400 = $3,200 → Repair
Other replacement triggers:
- Furnace 18+ years old
- Cracked heat exchanger (carbon monoxide risk)
- Frequent breakdowns (3+ repairs in 2 years)
- Efficiency under 80%
What Our Customers Say
Cracked heat exchanger – immediate replacement required
“My furnace stopped working for a few days. Lance and Keith came the day after I called, explained why the old furnace (35 years) needed to be replaced, and the next day they came and did a remove/replace in about 3 hours. Worked perfectly.”
— Paul, Denver Metro
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