A heat pump is one system that can both heat and cool a home.
Most residential heat pumps use a refrigeration cycle powered by electricity. Instead of relying on combustion or electric resistance as the primary way to create space heat, the system transfers heat. In cooling mode it moves heat out of the house; in heating mode it moves heat in.
That basic technology can be packaged in very different ways. A heat pump may use central ducts, serve rooms or zones without ducts, operate as the main heating system, or work alongside a furnace. The useful question is which setup fits the house, climate, existing equipment, comfort goal, and project scope.
This page explains the category. It does not choose a final system size or model. Those decisions depend on house-specific load, equipment performance, distribution, controls, and project constraints.
- Heating
-
Moves heat indoors
Outdoor heat is collected and transferred into the home.
- Cooling
-
Moves heat outdoors
The same basic refrigeration process works in the cooling direction.
- Power
-
Uses electricity to move heat
Much of the delivered heat comes from the outdoor environment, so the heat delivered to the home can exceed the electrical energy consumed by the compressor and fans.
A heat pump overlaps with both an air conditioner and a furnace, but it is not the same as either one.
The easiest way to understand the category is to separate the job each system performs. A central air conditioner provides cooling. A furnace provides heating. A reversible heat pump can provide both by running the refrigeration cycle in either direction.
- System
-
Central air conditioner
Cooling: Yes · Heating: No
Typical role: Cooling only, usually paired with a separate heating system.
- System
-
Furnace
Cooling: No · Heating: Yes
Typical role: Creates heat from a fuel or, in some cases, electricity.
- System
-
Heat pump
Cooling: Yes · Heating: Yes
Typical role: Moves heat in either direction and can serve as the main heating-and-cooling system.
A heat pump can also be paired with a furnace. That is usually called a dual-fuel or hybrid setup. The furnace is then a second heat source rather than the only heating system.
The core idea is simple: the refrigerant loop carries heat between indoors and outdoors.
A typical residential heat pump uses an outdoor unit, an indoor coil or indoor unit, refrigerant, a compressor, fans, and metering and control components. The refrigerant absorbs heat at one side of the system and releases it at the other. In reversible systems, a reversing valve changes which coil acts as the evaporator and which acts as the condenser.
Homeowners do not need to follow every pressure and phase change to make an early decision. The important point is that the same refrigeration system can move heat in either direction, which is why one system can provide both cooling and heating.
- Winter
-
Outdoor air → Heat pump → Home
Moves heat in
- Summer
-
Home → Heat pump → Outdoor air
Moves heat out
“Heat pump” describes the technology. The home setup can look very different.
Several decisions are often collapsed into the phrase “heat pump”: ducts or no ducts, whole home or selected rooms, whether an existing furnace stays, and whether the heat source is outdoor air or the ground. Those are separate system-design choices.
- Air-source
-
Ducted heat pump
Uses a central indoor air handler and ducts to distribute conditioned air. It can replace the cooling role of a central AC and may also replace or share the heating role of a furnace.
Air-source heat pumps - Ductless
-
Mini-split heat pump
Uses one outdoor unit with one or more indoor units and does not depend on a central duct system. It can serve selected rooms, zones, additions, or a whole home when designed that way.
Ductless and mini-split systems - Hybrid
-
Heat pump plus furnace
Retains a furnace as a second heat source. The operating strategy depends on equipment capability, controls, climate, energy prices, and the design of the system.
Dual-fuel heat pumps - Ground-source
-
Geothermal heat pump
Moves heat through a ground loop instead of exchanging heat directly with outdoor air. It belongs to the same broad heat-pump family but has a very different project scope and installation profile.
Geothermal heat pumps
Yes, heat pumps can work when it is cold outside. The model and the design still matter.
Outdoor air still contains usable heat below freezing, and modern air-source heat pumps can operate in subfreezing weather. Cold-weather suitability is therefore not a simple yes-or-no property of the category.
As outdoor temperature falls, heating capacity and efficiency can change, and the pattern varies by model. A cold-climate decision should compare the home’s design load with model-specific low-temperature performance rather than rely on the words “heat pump” or a generic climate label.
Backup heat is a design choice, not an automatic requirement. Whether a project needs electric resistance, a retained furnace, another backup source, or no separate backup depends on the home’s load, the selected equipment, controls, comfort target, and local design conditions.
“It gets cold here” and “this model is a cold-climate heat pump” are different statements. The project still needs a house-specific load basis and model-specific low-temperature performance.
A heat pump is not sized from square footage alone.
Heat-pump capacity should be tied to the home’s heating and cooling loads, not to floor area alone. Insulation, air leakage, windows, orientation, climate, conditioned extent, duct location and leakage, and indoor design conditions can all change those loads.
For residential HVAC design, ACCA Manual J is the ANSI-recognized method for calculating heating and cooling loads. Equipment selection then uses those loads together with manufacturer performance data under Manual S. Operating history can be a useful second check on a sizing claim, but it is not a substitute for the load calculation, room-by-room design where needed, or final equipment selection.
- 01
-
House load
Establish what the building needs under the design condition.
- 02
-
Equipment performance
Check how the candidate system performs at the relevant outdoor temperatures.
- 03
-
Distribution and controls
Confirm ducts, zones, air delivery, backup strategy, and control behavior.
Already have a sizing claim or quote? Check the evidence behind it
A useful heat-pump quote should tell you more than a model number and a total price.
The quote is where the technology becomes a real project. Separate the equipment decision from the work scope so two proposals can be compared on the same basis.
- System
-
What equipment is proposed?
Exact outdoor and indoor model numbers, system type, matched configuration, and any backup heat. For certified split-system ratings, an AHRI Certified Reference Number can help verify that the proposed indoor and outdoor units are a rated combination.
- Size
-
How was the size chosen?
Ask what residential load calculation supports the proposal and which heating and cooling design conditions were used. A square-feet-per-ton rule of thumb is not the same thing as a load calculation.
- House
-
What existing conditions are assumed?
Ducts, electrical service, conditioned area, envelope work, thermostat and controls, and retained equipment.
- Work
-
What is included in installation?
Removal, electrical work, duct changes, line-set work, condensate, permits, startup, commissioning, and cleanup.
- Performance
-
What does the system do in cold weather?
Use model-specific capacity and efficiency evidence at relevant outdoor temperatures.
- Afterward
-
What happens after startup?
Warranty, maintenance, service responsibility, controls setup, and any follow-up balancing or commissioning.
A quote can be reviewed before every project decision is closed. Quote structure alone does not prove that the proposed system, size, or price is correct.
Heat pump basics: common homeowner questions
Is a mini-split the same thing as a heat pump?
A mini-split can be a heat pump, but “heat pump” is the broader category. Many central ducted systems are also heat pumps.
Can a heat pump replace both my furnace and air conditioner?
It can replace both functions in many projects, but whether the furnace should be removed, retained as backup, or replaced by another configuration depends on the house, climate, load, equipment, and project goals.
Do heat pumps work below freezing?
Yes, many modern systems do. Low-temperature capacity differs by model, so cold-weather suitability should be checked with model-specific performance and a house-specific load basis.
Do I need ducts?
No. Ducted heat pumps use central ducts; ductless mini-split systems use indoor units that serve rooms or zones directly.
Do I always need backup heat?
No. Some homes and systems are designed around the heat pump alone, while others use electric resistance, a furnace, or another source as backup. The right answer is design-specific.
Is a bigger heat pump better?
No. Oversized and undersized equipment can both create comfort and performance problems. Capacity should follow the calculated loads and the candidate equipment’s performance at the relevant design conditions.
Is a heat pump always cheaper to run than a furnace?
Not automatically. Operating cost depends on equipment efficiency, outdoor conditions, electricity and fuel prices, controls, the building load, and the heating system being compared.
Does this page cover heat-pump water heaters or pool heat pumps?
No. These guides cover heat pumps used for home heating and cooling. Heat-pump water heaters and pool heat pumps are different products.
How do I know if I already have a heat pump?
Check the equipment model information or system documentation rather than relying on the outdoor unit’s appearance alone. A conventional central air conditioner can look similar outside, while a heat pump is designed to provide heating as well as cooling.