Do Heat Pumps Work in Chicago Winters?

Heat pumps are getting a lot of attention, and for good reason. They heat and cool with one system, and modern models are far more capable than the heat pumps of a few decades ago. But Chicago is not Atlanta. A January polar vortex can push temperatures well below zero, and many homeowners understandably wonder whether a heat pump can keep up.

The honest answer is that a well-chosen, well-installed heat pump can heat a Chicago home through most of the winter, and with the right backup plan, through all of it. This guide explains how heat pumps work in cold weather, what cold-climate models change, the backup options and which homes are good candidates. For service on an existing system, see our heat pump repair page.

How a Heat Pump Heats

A heat pump is essentially an air conditioner that can run in reverse. In summer, it moves heat from inside your home to the outdoors. In winter, it pulls heat from the outdoor air and moves it inside. Even very cold air contains heat energy, and the refrigerant in a heat pump is cold enough to absorb it.

Because a heat pump moves heat rather than creating it by burning fuel or heating a resistance element, it can deliver more heat energy than the electricity it uses. That ratio is called the coefficient of performance, or COP. A COP of 3 means the heat pump delivers three units of heat for every unit of electricity.

What Happens as It Gets Colder

As outdoor temperatures fall, there is less heat to collect, and the heat pump has to work harder. Two things happen:

• Capacity drops. The heat pump produces less heat per hour, just as the house needs more.
• Efficiency drops. The COP decreases, although well-designed units can remain more efficient than electric resistance heat even in very cold weather.

At some outdoor temperature, called the balance point, the heat pump's output equals the home's heat loss. Below that temperature, it needs help from backup heat to keep the house at the setpoint.

Older Heat Pumps vs. Cold-Climate Heat Pumps

Older single-speed heat pumps lost capacity quickly in cold weather and often relied heavily on electric backup heat once temperatures fell into the 20s or 30s. That gave heat pumps a reputation for not working in northern climates.

Modern cold-climate heat pumps use variable-speed inverter compressors and refrigerant systems designed for low temperatures. Many keep delivering a large share of their rated capacity at 5 degrees Fahrenheit, and some are rated to operate below 0 degrees. ENERGY STAR now offers a cold-climate designation that includes a minimum efficiency at 5 degrees. When shopping, ask for performance data at 5 degrees and below, not just at mild temperatures.

How Cold Does Chicago Get?

Chicago's typical winter includes long stretches in the 20s and 30s, with colder spells in the teens and single digits. A few times a winter, or during a polar vortex, temperatures can drop below zero. Heating systems in Chicago are generally designed for a cold design temperature in the low single digits or below. A heat pump plan should cover those design conditions comfortably, with a backup for the extremes.

Much of the season, though, is well within a cold-climate heat pump's comfortable range. That is why many Chicago homeowners use heat pumps for the majority of their heating hours, and let backup heat handle the coldest days.

Backup Heat Options

Electric Resistance Heat Strips

Many heat pump air handlers include electric heat strips that turn on when the heat pump cannot keep up, or during defrost. They are simple and reliable, but they use a lot of electricity. If they run often, operating costs can rise sharply. Correct sizing and controls that limit their use are important.

Dual-Fuel With a Gas Furnace

A popular Chicago option is pairing a heat pump with a gas furnace. The heat pump handles heating in milder weather, and the furnace takes over below a set outdoor temperature. This keeps comfort high in deep cold and lets you choose the cheaper fuel depending on conditions. Our guide on dual-fuel HVAC systems explains how it works.

Existing Boiler or Radiators

In homes with radiators, ductless heat pumps can provide efficient heat and cooling in many rooms, while the boiler remains as backup for the coldest days. This approach is common in Chicago two-flats and greystones.

Ducted vs. Ductless Heat Pumps

• Ducted heat pumps replace or work alongside a central AC and connect to existing ductwork. They suit homes with good ducts.
• Ductless mini-split heat pumps mount indoor units in individual rooms and need no ducts. They suit homes with radiators, additions, finished attics and condos. See our guide on ductless mini-splits for Chicago homes.

Defrost Cycles Are Normal

In winter, frost forms on the outdoor coil as the heat pump pulls heat from cold, humid air. Every so often, the heat pump runs a defrost cycle to melt it. You may see steam rising from the outdoor unit and hear a whoosh as the system switches modes. During defrost, the indoor air may feel cooler briefly unless backup heat runs. This is normal operation. Our guide on heat pump blowing cold air explains how to tell defrost from a real problem.

Which Chicago Homes Are Good Candidates?

• Homes with central air that needs replacement anyway.
• Homes with reasonably good insulation and air sealing.
• Homes with radiators that want efficient cooling and supplemental heat through ductless units.
• Additions, attics and rooms that the main system does not serve well.
• Owners interested in reducing gas use or preparing for future electrification.

Drafty homes with little insulation can still use heat pumps, but they will need larger capacity or more backup. Improving the building envelope first often makes the heat pump smaller and cheaper to run.

Operating Costs: Gas vs. Heat Pump

Whether a heat pump costs less to run than a gas furnace depends on electricity rates, gas rates, the heat pump's efficiency across the season and how much backup heat is used. In some Chicago homes, a cold-climate heat pump paired with gas backup reduces total heating costs. In others, gas remains cheaper per unit of heat. A contractor should estimate seasonal operating costs for your specific home and rates, rather than relying on general claims.

Incentives

Utilities serving Chicago have offered rebates for qualifying heat pumps, and program details change frequently. Check current ComEd and Peoples Gas program information before buying. Note that the federal energy efficient home improvement tax credit, which covered many heat pumps, expired for equipment placed in service after December 31, 2025.

Installation Quality Matters More Than Ever

• Size the heat pump with a heating and cooling load calculation, not a rule of thumb.
• Place the outdoor unit where snow, ice and roof runoff will not bury or damage it. Elevated stands are common in Chicago.
• Make sure defrost water can drain and will not freeze into a hazard on walkways.
• Configure controls and backup heat settings carefully.
• Check that existing ductwork can deliver enough airflow.

Maintenance for Chicago Heat Pumps

Heat pumps run in both heating and cooling seasons, so they work more hours per year than an AC alone. Regular filter changes, keeping the outdoor unit clear of snow and debris, and professional service help them perform well. See our tune-up and maintenance page.

Understanding Heat Pump Ratings

Heat pump specifications can be confusing. A few terms are worth knowing when you compare equipment:

• HSPF2 is a seasonal heating efficiency rating. Higher is better, but it is based on a standardized climate that may not reflect a Chicago winter.
• SEER2 is the seasonal cooling efficiency rating.
• COP at 5 degrees Fahrenheit shows efficiency at a cold temperature, which is more relevant in Chicago than seasonal averages.
• Capacity at 5 degrees and 17 degrees shows how much heat the unit delivers in cold weather compared with its rating at 47 degrees.
• Minimum operating temperature shows how cold it can get before the heat pump shuts down and backup takes over completely.

Ask contractors for the manufacturer's extended performance data, not just the brochure numbers. A heat pump that keeps most of its capacity at 5 degrees will need far less backup heat in Chicago than one that loses half its capacity.

Electrical Service Considerations

Switching to heat pump heating can increase electrical demand, especially if large electric backup strips are installed. Many older Chicago homes have 60- or 100-amp electrical service that may need evaluation. A contractor should check panel capacity and the available space for new breakers. Dual-fuel systems, which use a gas furnace as backup instead of electric strips, often avoid the need for a service upgrade.

What Real Chicago Heat Pump Owners Notice

People who switch from a furnace to a heat pump commonly notice a few differences. The system runs longer and more steadily rather than in short, hot blasts. The air from the vents feels warm but not hot. The outdoor unit runs in winter, sometimes with visible steam during defrost. Large thermostat setbacks overnight are less useful, because heat pumps recover more slowly and may call on backup heat to catch up. Many owners set a steady temperature and let the system run, which tends to be both comfortable and efficient.

Heat Pumps and Older Chicago Housing

Many Chicago homes were built long before modern insulation standards. Heat pumps can still work in older homes, but the building's heat loss determines how much capacity and backup are needed. Simple improvements such as attic air sealing and insulation, weatherstripping doors, and sealing gaps around windows and plumbing penetrations reduce heat loss and make a heat pump more effective. In two-flats and greystones with radiators, ductless heat pumps for living areas and bedrooms paired with the existing boiler are often a practical first step.

Questions to Ask Before You Buy

• What is this heat pump's heating capacity and COP at 5 degrees Fahrenheit?
• At what outdoor temperature will backup heat start, and what kind of backup is it?
• Have you done a heat loss calculation for my home?
• Where will the outdoor unit go, and how will snow and defrost water be handled?
• Does my electrical panel have enough capacity?

Thinking About a Heat Pump?

Call (312) 638-0812 to discuss whether a heat pump, ductless system or dual-fuel setup suits your home. We work across neighborhoods such as Lincoln Park, Jefferson Park and Edgebrook. Compare options in our guide on heat pump vs. furnace for Chicago homes.