Quick answer
A heat pump is an electric appliance that moves heat from one place to another instead of generating it directly. In winter, it pulls heat from outdoor air, the ground, or a water source and pumps it inside to warm your home. In summer, it reverses direction and acts like an air conditioner, pulling heat from inside and dumping it outdoors. Because it transfers heat rather than creating it, a well-installed heat pump can deliver two to four times more heating energy than the electricity it consumes, making it one of the most efficient ways to heat and cool a house.
How it works
A heat pump transfers heat from one place to another using a refrigeration cycle, rather than generating heat directly. It uses a compressor and refrigerant to absorb heat from outside air—even in cold weather—and release it indoors for heating, or reverse the cycle for cooling.
Types of heat pumps
Heat pumps come in several configurations, and the right one depends on your home's layout, climate, and existing ductwork. The most common split is between air-source and ground-source (geothermal) systems, but within air-source you'll find ducted, ductless mini-splits, and packaged units.
Ducted air-source heat pumps connect to your home's existing ductwork, making them a straightforward swap if you already have a forced-air furnace. Ductless mini-splits skip the ducts entirely — an outdoor unit connects to one or more indoor heads mounted on walls or ceilings, which is handy for additions or homes without ducts. Packaged terminal heat pumps (PTHP) and single package vertical heat pumps (SPVHP) are self-contained units often used in apartments or commercial spaces, and they're now included in the NEEP ccASHP Version 4.0 specification alongside variable refrigerant flow (VRF) multi-split heat pumps 1.
Inverter-driven compressors are becoming the standard in modern heat pumps. Unlike older single-speed units that cycle on and off, an inverter heat pump continuously adjusts compressor speed to match the heating or cooling demand. Daikin's inverter models, for instance, ramp up or down to maintain a steady indoor temperature, which saves energy and reduces CO₂ emissions 2.
If you live in a colder region, look for a cold-climate heat pump. The DOE Cold Climate Heat Pump Challenge set performance targets for these units: for systems with heating capacity up to 48,000 Btu/hr, the required coefficient of performance (COP) is higher than for larger units, where physical constraints make it harder to hit the same efficiency 3. So a 3-ton cold-climate unit will typically have a slightly better COP rating than a 5-ton model from the same line.
Geothermal heat pumps use the stable temperature underground instead of outdoor air. They're more expensive to install but deliver consistent efficiency year-round. Your choice ultimately comes down to your budget, your home's setup, and how cold your winters get.
Efficiency ratings: SEER2 and HSPF2
When you're comparing heat pumps, you'll see two main efficiency numbers: SEER2 for cooling and HSPF2 for heating. Higher numbers mean better efficiency, so a unit with a 20 SEER2 will cost less to cool your home than one rated at 15 SEER2 4.
The Department of Energy sets minimums that every new heat pump must meet. For split systems, you need an HSPF2 of at least 7.5, and packaged units need 6.7 or higher 5. If you're looking for an ENERGY STAR certified model, the bar is higher—split systems must hit 15.2 SEER2 and 7.8 HSPF2, while single-package equipment needs 15.2 SEER2 and 7.2 HSPF2 6.
If you live in a colder climate, pay extra attention to HSPF2. Cold climate heat pumps are designed to keep delivering heat when temperatures drop, and ENERGY STAR requires them to reach even higher heating efficiency: 8.5 HSPF2 for non-ducted split systems and 8.1 for ducted split systems 6. That extra margin can make a real difference in your winter energy bills.
When this matters for you
If you're replacing an old furnace or boiler, the efficiency difference between a standard heat pump and a high-efficiency model can cut your heating bill by hundreds each year. But the real payoff comes when you're eligible for incentives. In New York, for example, NYSERDA requires heat pump equipment to meet minimum program efficiency requirements for incentives in 1-4 family homes 7. So if you're planning an installation and hoping to claim a rebate, you'll need to check that the unit you're eyeing is on the approved list. Even without incentives, choosing a model with a higher HSPF2 or SEER2 rating means lower operating costs over the 15- to 20-year life of the system.
Standards and codes
When you're installing a heat pump, you're not just picking a unit off the shelf — you're working within a framework of codes and standards that keep the system safe, efficient, and legal. These rules cover everything from freeze protection to performance ratings, and they vary by location.
In colder climates, protecting pipes from freezing is a top priority. The International Plumbing Code (IPC) Section 305.6 says pipes in areas subject to freezing must be protected by insulation, heat, or both 8. New York City takes it a step further: Building Code 1204.3 requires active or passive systems to prevent wet piping from freezing at all times, including permanently installed heat tracing 9. If you're in a region with harsh winters, you'll need to plan for these measures early in the design.
For commercial and multifamily buildings, ASHRAE offers a detailed Heat Pump Application and Operation Guide. It walks you through design, sizing for different climate zones, refrigerants, electrical requirements, and control strategies 10. This guide is especially useful if you're dealing with larger systems where efficiency and code compliance get more complex.
On the performance side, look for Energy Star certification. Heat pumps that earn the label meet strict efficiency criteria, which can also qualify you for rebates 6. Manufacturers like Carrier and Trane publish detailed efficiency metrics — SEER2, HSPF2, and EER2 — that help you compare models 45. And if you're in a cold climate, check the NEEP ccASHP specification list for units proven to perform well below freezing 1.
⚠️ Warning: Skipping freeze protection in a cold climate can lead to burst pipes and catastrophic water damage. Always verify local code requirements before installation.
Still unsure which codes apply to your project? A common follow-up is confusion between state and local rules. Start with your municipal building department — they'll tell you which codes are enforced and whether you need a permit. For heat pump specifics, the DOE Cold Climate Heat Pump Challenge results can also guide you toward models that meet emerging performance standards 3.
Frequently Asked Questions
How much does a heat pump cost? A whole-home air-source heat pump system typically runs between $4,000 and $12,000 installed, depending on the size of your home, the unit's efficiency, and local labor rates. Ductless mini-split systems often fall on the lower end of that range. Federal tax credits and local utility rebates can knock 30% or more off the final price, so check what's available in your area before you budget.
How long does a heat pump last? With regular maintenance—cleaning filters, keeping the outdoor coil clear, and an annual professional checkup—most heat pumps last 15 to 20 years. Coastal installations may see shorter lifespans because of salt corrosion, while units in moderate climates often outlast that range. The compressor is the big-ticket component; once it fails, replacement usually makes more sense than repair.
Does a heat pump work in really cold weather? Yes, modern cold-climate heat pumps are designed to deliver heat at outdoor temperatures well below freezing. The Department of Energy's Cold Climate Heat Pump Challenge demonstrated units that maintain 100% heating capacity at 5��F and still operate efficiently at -15°F 3. If you live where temperatures routinely dip below -15°F, you'll want a system with a backup heat source—either electric resistance strips or a gas furnace—but for most U.S. climates, a properly sized heat pump handles winter on its own.
Are heat pumps noisy? Older models earned a reputation for being loud, but today's units are much quieter. The outdoor compressor typically hums at 50 to 60 decibels—about the level of a normal conversation. Indoor air handlers are even quieter. If your current outdoor unit sits right outside a bedroom window, look for a model with a sound rating below 55 dB and consider vibration isolation pads during installation.
Do I need to replace my ductwork? Not necessarily. If your existing ducts are in good shape—no major leaks, properly sized, and well-insulated—a heat pump can often connect to them directly. Leaky or undersized ducts will hurt efficiency and comfort, so have a contractor inspect them first. If you don't have ducts, a ductless mini-split system avoids the issue entirely.
What's the difference between a heat pump and a furnace? A furnace burns fuel (gas, oil, or propane) or uses electric resistance to create heat. A heat pump doesn't create heat—it moves it. In winter, it pulls heat from outdoor air and pumps it inside; in summer, it reverses to act like an air conditioner. Because it moves heat rather than generating it, a heat pump can be 200–300% efficient, meaning it delivers two to three times more heat energy than the electricity it consumes.
How often should I maintain my heat pump? Plan on two DIY checks a year: clean or replace the air filter every one to three months, and keep the outdoor coil free of leaves, grass clippings, and snow. Schedule a professional tune-up once a year—ideally in the fall before heating season—to check refrigerant levels, electrical connections, and overall performance. A well-maintained heat pump runs quieter, lasts longer, and keeps your energy bills in check.