A heat pump that runs all the time is usually working as designed, but it can signal a problem worth investigating

Heat pumps run longer and more often than furnaces because they move heat rather than generate it, so they need more runtime to reach your target temperature. In cold weather, a heat pump may run continuously for hours or even all day without stopping — this is normal. But if your heat pump runs constantly even when outdoor temperatures are mild, or if your heating bills have jumped sharply, something is likely wrong: a refrigerant leak, a failing compressor, a blocked filter, or a thermostat set too high.

The difference between normal and abnormal runtime comes down to outdoor temperature, how well your home holds heat, and what your thermostat is actually asking the system to do. Understanding which situation you are in will tell you whether to call a technician or straightforward adjust your expectations.

Key Takeaways

  • Heat pumps in heating mode run much longer than furnaces because they move existing heat rather than burning fuel, so continuous runtime in winter is often normal.
  • A heat pump running constantly in mild weather (above 40°F) or with rising energy bills usually means a refrigerant leak, compressor failure, or airflow blockage that needs professional repair.
  • Auxiliary heat (electric resistance strips) kicking in during cold snaps will make runtime longer and energy use higher, which is expected but expensive.
  • A thermostat set above 72°F, a dirty filter, or poor insulation will all cause longer runtime; fixing the filter or lowering the setpoint costs nothing.

Why heat pumps run longer than furnaces in winter

A furnace burns fuel to create heat and delivers it quickly. A heat pump extracts heat from outdoor air (even cold air contains some heat) and moves it indoors, a slower process that requires the compressor to run longer to reach the same temperature. In heating mode, your heat pump may run for 8, 10, or even 12 hours straight on a cold day without ever shutting off. This is not a malfunction.

The colder it gets outside, the longer your heat pump must run. Below 32°F, the system works harder. Below 20°F, it works much harder. Below your heat pump's balance point — usually around 35°F to 45°F depending on the model and your home's insulation — the system may run almost continuously and still struggle to keep up. At that point, auxiliary heat (electric resistance coils) may turn on to help, which is normal but expensive.

If outdoor temperatures are above 40°F and your heat pump is running all day, or if it is running constantly in spring or fall when you are only asking for mild heating, the problem is not the design of the system.

Refrigerant leaks and compressor failure

A refrigerant leak is the most common reason a heat pump runs constantly without reaching temperature. The system has less refrigerant to circulate, so the compressor must work longer to move the same amount of heat. You may notice the indoor coil frosting over, weak airflow from the vents, or a hissing sound near the outdoor unit. Your heating bills will climb even though your home is not getting warmer.

A failing compressor has the same effect: the pump that moves refrigerant through the system loses efficiency, so it runs longer to do the same job. Compressor failure is expensive to repair — often $1,500 to $3,000 — and is more common in systems over 10 years old or in units that have been running low on refrigerant for months.

Both problems require a technician with refrigerant certification to diagnose and repair. If you suspect a leak, turn off auxiliary heat in your thermostat settings (if available) to avoid running up the bill while you wait for service. Do not try to add refrigerant yourself; the system must be properly charged by weight, not by pressure alone.

Blocked filters and airflow problems

A dirty filter forces your heat pump to work harder to pull air through the coils. The system runs longer to deliver the same amount of heat, and you may feel weak airflow from your vents. This is one of the easiest problems to fix: replace your filter every 30 days during heating season, or every 60 to 90 days if you have pets or live in a dusty area.

Blocked vents, closed dampers, or furniture blocking return-air grilles have the same effect. Walk through your home and make sure all supply vents are open and unobstructed, and that nothing is blocking the return-air grille (usually a large vent in a wall or ceiling). If you have a zoned system with dampers in the ductwork, make sure the zones you want heated are actually open.

Ductwork leaks also force longer runtime. If your ducts are old or poorly sealed, heated air escapes before it reaches your rooms, so the system must run longer to compensate. Sealing visible leaks with mastic or metal tape is a low-cost fix; a professional duct sealing service costs more but can recover 10 to 20 percent of lost heating.

Thermostat settings and balance point

A thermostat set to 74°F or 75°F will cause longer runtime than one set to 70°F, especially in cold weather. Each degree of setpoint increase can add 3 to 5 percent to your heating runtime. If you have raised your thermostat because you are cold, the problem may not be the heat pump — it may be insulation, air leaks, or a room that is far from the outdoor unit.

Check whether your thermostat is set to heat pump only or heat pump with auxiliary. If it is set to auxiliary only, your heat pump is not running at all. If it is set to "emergency heat," the system is using only the electric resistance coils and bypassing the heat pump entirely, which will run up your bill fast.

Some thermostats have a balance point setting that tells the system when to switch to auxiliary heat. If this is set too high — say, 50°F instead of 35°F — auxiliary heat will run during mild cold snaps when the heat pump alone could handle the load. Lowering the balance point to match your system's actual capability will reduce runtime and energy use.

Insulation and air sealing

A heat pump in a poorly insulated home will run longer because heat escapes faster than the system can replace it. If your home has old insulation, single-pane windows, or air leaks around doors and windows, your heat pump will run almost constantly in winter and still not keep up. This is not a heat pump problem — it is a building envelope problem.

Before paying for a new heat pump, have a professional energy audit done. Many utilities offer these at low cost or free. An audit will show you where heat is escaping and what repairs will give you the best return. Sealing air leaks around outlets, baseboards, and attic hatches is cheap and effective. Adding insulation to an attic is more expensive but can cut heating runtime by 20 to 30 percent.

If you have just installed a new heat pump in an old, leaky home, expect longer runtime than you might have seen with a furnace. The heat pump is more efficient per unit of heat delivered, but it cannot overcome a building that loses heat faster than any system can replace it.

Auxiliary heat and cold-weather operation

Most heat pumps have electric resistance coils (auxiliary heat) that turn on automatically when outdoor temperature drops below the balance point, usually around 35°F to 40°F. When auxiliary heat is running, your system uses much more electricity and your bills will spike. This is normal in January and February, but if auxiliary heat is running in October or April, something is wrong.

You can check whether auxiliary heat is running by looking at your thermostat display — many show an "AUX" or "EM" indicator when the coils are active. If auxiliary heat is running constantly even in mild weather, your heat pump may not be working at all, or refrigerant loss may have forced the system to rely on the coils to meet demand.

Auxiliary heat is expensive to run — often 2 to 3 times the cost of the heat pump alone — so if it is running more than a few days per month, have a technician check your system's refrigerant charge and compressor performance.

When to call a technician

Call a technician if your heat pump is running constantly but your home is not reaching temperature, if you see frost on the outdoor unit, if your heating bills have jumped 30 percent or more, or if auxiliary heat is running in mild weather. A service call costs $100 to $200 and will identify whether the problem is a leak, a compressor issue, or something simpler like a clogged filter or thermostat misconfiguration.

If your heat pump is running constantly but your home is warm and your bills are normal, the system is likely working as designed. Heat pumps in cold climates run longer than furnaces — that is how they work. If you are uncomfortable with the runtime or the noise, the real solution is usually better insulation or air sealing, not a new system.

Frequently Asked Questions

Is it normal for a heat pump to run 24 hours a day in winter?

Yes, in temperatures below 35°F. A heat pump extracts heat from outdoor air and moves it indoors, a slower process than burning fuel, so it must run much longer to reach your target temperature. If outdoor temperature is above 40°F and the system is still running constantly, something is wrong.

Why is my heat pump running but my house is still cold?

The most common causes are a refrigerant leak, a clogged filter, or a thermostat set to emergency heat instead of heat pump mode. Check your filter first — a dirty filter blocks airflow and forces the system to run longer without delivering heat. If the filter is clean, have a technician check the refrigerant charge and compressor.

How much should my heating bill go up when I switch to a heat pump?

In mild climates, a heat pump usually costs less to operate than a furnace. In cold climates, expect higher bills in January and February when auxiliary heat is running. If your bill has jumped 50 percent or more, check whether auxiliary heat is running constantly, or whether a refrigerant leak is forcing the system to work harder.

Can I lower my heating bills by turning off my heat pump and using only auxiliary heat?

No. Auxiliary heat (electric resistance) costs 2 to 3 times more per unit of heat than the heat pump. Running only auxiliary heat will increase your bill, not lower it. If you are trying to save money, lower your thermostat setpoint or improve your home's insulation instead.

What is the balance point and why does it matter?

The balance point is the outdoor temperature at which your heat pump can no longer keep up with heat loss from your home, so auxiliary heat turns on. Most systems have a balance point around 35°F to 40°F. If your thermostat balance point is set too high, auxiliary heat will run during mild cold snaps when the heat pump alone could handle the load, wasting money.