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The core difference is that a heat pump can both heat and cool your home, while an air conditioner only cools. In cooling mode, they're functionally identical — same compressor, same refrigerant cycle, same SEER2 efficiency ratings. The heat pump simply adds a reversing valve that lets it run the refrigerant cycle in reverse to provide heating, eliminating the need for a separate furnace.
In 2026, a ducted heat pump costs $5,800–$10,000 installed versus $3,500–$6,000 for a central AC (which still requires a separate $2,000–$4,500 furnace for heating). When you factor in the heat pump's lower operating costs and available tax credits, the heat pump is the better investment for most homeowners.
Side-by-Side Comparison
Total system includes installation. AC cost includes a mid-range gas furnace. *Based on 2,000 sq ft home, zone 4, $0.14/kWh, $1.30/therm gas.
How They Work (The Technical Difference)
An air conditioner and a heat pump use the exact same refrigerant cycle for cooling. Both have a compressor, condenser coil, expansion valve, and evaporator coil. The compressor pumps refrigerant in a loop: the refrigerant absorbs heat from indoor air at the evaporator coil, then releases that heat outdoors at the condenser coil.
The heat pump adds one critical component: a reversing valve. This valve lets the system switch the direction of refrigerant flow, swapping the roles of the indoor and outdoor coils. In heating mode, the outdoor coil becomes the evaporator (absorbing heat from outside air) and the indoor coil becomes the condenser (releasing heat into your home).
That's it. The reversing valve and its associated controls are the only hardware difference. A heat pump outdoor unit looks identical to an AC condenser, weighs about the same, and connects to the same type of indoor air handler or coil.
Why the Price Difference Is Small: Since a heat pump is essentially an AC with a reversing valve added, the equipment cost premium is only $500–$1,500. The difference in installed cost comes from additional components like the defrost control board, a supplemental heat strip for backup, and slightly more complex controls.
Cooling Performance: Are They Equal?
In cooling mode, a heat pump and an air conditioner of the same SEER2 rating perform identically. A SEER2 18 heat pump and a SEER2 18 AC will deliver the same amount of cooling per watt of electricity, produce the same dehumidification, and use the same amount of energy to cool your home.
The only cooling-related difference: in extremely hot climates (Phoenix, Las Vegas), some contractors prefer AC-only systems because the reversing valve in a heat pump introduces one additional potential failure point. However, modern reversing valves are highly reliable, and this concern is largely outdated.
Cost Comparison: Equipment + Operating
The real cost comparison must account for the total HVAC system. An AC needs a furnace for heating; a heat pump handles both.
The 10-Year Math: Even in the worst case (high electricity, cheap gas), the heat pump saves $3,800 over 10 years. In the best case (moderate electricity rates, higher gas prices, plus state rebates), the savings exceed $10,000 over the heat pump's lifetime.
Efficiency Comparison
Cooling Efficiency
In cooling mode, both systems use the same SEER2 scale. The federal minimum in 2026 is SEER2 13.4 (northern region) or 14.3 (southern region). Premium models from both categories reach SEER2 20–22. There is no inherent efficiency advantage to either system in cooling mode.
Heating Efficiency
Here's where the heat pump dominates. A gas furnace converts fuel to heat at 80–98% efficiency (0.80–0.98 COP equivalent). A heat pump delivers COP 2.5–4.5, meaning it produces 2.5–4.5 units of heat for every unit of electricity consumed.
Assumes $0.14/kWh, $1.30/therm gas, $3.50/gal oil.
At current national average rates, a heat pump with HSPF2 10 heats for about the same cost per BTU as a 96% gas furnace. But the heat pump also eliminates the gas service charge ($10–$20/month) and provides cooling — making it the more economical total system.
Lifespan and Maintenance
Lifespan
A central AC condenser lasts 15–20 years. A heat pump outdoor unit also lasts 15–20 years. The difference is cumulative runtime: the heat pump runs year-round (heating + cooling), logging 2,500–4,500 hours annually, while the AC runs only during the cooling season (1,000–2,000 hours).
A gas furnace typically lasts 20–30 years. So if you install an AC + furnace at the same time, you'll likely replace the AC once during the furnace's lifetime. With a heat pump, you replace the single system every 15–20 years.
Assumes current rates with 2% annual escalation. Zone 4, 2,000 sq ft.
Maintenance
Both systems require the same basic maintenance: annual professional tune-up ($80–$200), monthly filter changes, and outdoor unit cleaning. The heat pump's additional maintenance need is related to the reversing valve and defrost system — checked during the annual service call at no extra cost.
The AC + furnace combo requires separate maintenance: one tune-up for the AC in spring and one for the furnace in fall. Some contractors offer combo service plans. The furnace also needs periodic heat exchanger inspection (critical for safety, as a cracked heat exchanger can leak carbon monoxide).
Safety Advantage: A heat pump eliminates the risk of carbon monoxide leaks, gas line leaks, and combustion-related hazards entirely. If your home has gas appliances, you should have CO detectors regardless — but a heat pump removes one potential source.
When to Choose a Heat Pump
A heat pump is the better choice when:
You're replacing both your AC and furnace at the same time. The cost difference is minimal (or the heat pump is cheaper after incentives), and you get lower operating costs from day one.
You currently heat with oil, propane, or electric resistance. Savings of $1,000–$2,000/year make the heat pump pay for itself in 2–5 years.
Your state offers strong heat pump incentives. In Massachusetts, Maine, New York, California, and many other states, stacked incentives make the heat pump cheaper than a furnace + AC.
You want to simplify your HVAC. One system, one annual maintenance visit, one set of controls. No gas line, no combustion venting, no carbon monoxide risk.
You want to reduce your carbon footprint. A heat pump eliminates direct fossil fuel combustion in your home. Even if your electricity comes from the grid, the COP of 2.5–4.0 means lower net emissions than a gas furnace in all but the most coal-heavy grids.
Real-World Example — Nashville, TN: The Williams family needed to replace both their 18-year-old AC and 22-year-old gas furnace. They got quotes for both options: AC + furnace at $8,200 installed, heat pump at $8,900 installed. After the $2,000 federal tax credit, the heat pump was $1,300 cheaper. First-year operating savings: $450. The heat pump was the obvious choice.
When to Choose an Air Conditioner
An air conditioner (paired with a furnace) may be better when:
Your gas furnace is relatively new (under 8 years old) and only the AC needs replacing. Installing just an AC costs $3,500–$6,000 versus $5,800–$10,000 for a complete heat pump system. There's no financial reason to replace a working furnace.
Your electricity is very expensive (above $0.22/kWh) and gas is very cheap (below $0.90/therm). At those rates, the gas furnace has slightly lower heating operating costs.
You live in an extremely hot, dry climate and rarely heat. In Phoenix or Las Vegas, the heating season is minimal. The small operating cost savings from the heat pump may not justify even the modest upfront premium.
Your home can't support the electrical load. If a panel upgrade is required and you can't afford it, an AC replacement with your existing furnace avoids the electrical work.
Real-World Example — Scottsdale, AZ: The Patel family's 5-year-old 96% AFUE gas furnace was running fine, but their 14-year-old AC was failing. They chose a new Trane AC (SEER2 18) at $4,200 installed rather than a full heat pump at $8,500. With only 500 heating degree days in Phoenix, the heat pump's heating savings would have been under $150/year — a 28-year payback on the $4,300 difference.
Key Takeaways
In cooling mode, heat pumps and ACs perform identically at the same SEER2 rating. The heat pump adds heating capability via a reversing valve, eliminating the need for a separate furnace. After tax credits, a heat pump often costs less than an AC + furnace combo. Annual operating savings average $200–$500 versus gas and $1,000–$2,000 versus oil or propane. Choose a heat pump when replacing both heating and cooling equipment, or when switching from expensive fuel. Choose an AC when only your cooling system needs replacement and your furnace is still in good shape.