Leave your heat pump on all the time only if your home needs constant heating or cooling—otherwise, turning it off when you're away or sleeping saves money without damaging the equipment
Heat pumps are designed to run continuously without harm, but running one 24/7 costs more than cycling it on and off. The real question is whether the energy you save by turning it off outweighs the extra work the system does to reheat or cool your home when you turn it back on. For most households, the answer is to run the heat pump during occupied hours and lower the temperature when you leave or sleep.
The efficiency loss from restarting a heat pump is small—usually 5 to 10 percent of the energy used during that heating or cooling cycle. That's far less than the energy cost of maintaining your home at a comfortable temperature for 8 to 10 hours while nobody is there. The exception is if you live in an extremely cold climate and your backup heating system is expensive (like electric resistance heat), in which case keeping the heat pump running at a lower temperature might cost less than reheating from a cold start.
Key Takeaways
- Heat pumps can run continuously without damage, but leaving one on all the time costs more than turning it off when you're away or asleep.
- The energy penalty for restarting a heat pump is typically 5 to 10 percent of one heating or cooling cycle, much smaller than the cost of maintaining comfort for hours with nobody home.
- In very cold climates where backup heat is expensive, keeping the heat pump running at a lower setpoint while away may cost less than a full restart.
- A programmable or smart thermostat lets you automate temperature changes without remembering to adjust manually, making scheduled operation practical.
- Heat pumps reach steady state (stable operation) within 15 to 30 minutes of startup, so brief absences of an hour or less may not save money.
How Heat Pump Cycling Affects Your Energy Bill
When you turn a heat pump off and then restart it, the system must work harder for the first 15 to 30 minutes to bring your home back to the target temperature. During this ramp-up period, the compressor runs at full capacity and may trigger backup heating (if your system has it), both of which use more energy than steady-state operation. However, this startup penalty is a one-time cost per day or per absence, not an ongoing drain.
The hours the heat pump sits idle while you're away or sleeping represent the real savings. If you lower the temperature by 7 to 10 degrees while you sleep for 8 hours, you prevent the system from running continuously to maintain warmth. Over a winter month, that adds up to dozens of hours of avoided operation. The startup cost on the next morning is small compared to the energy you saved by not heating an empty or sleeping home all night.
The math changes if your absences are very short—say, an hour or less. In that case, the heat pump may not reach steady state before you return, and the startup penalty could exceed the savings from the brief idle period. For commutes of 8 hours or longer, turning the system off almost always saves money.
When Leaving Heat Pump On Makes Sense
In climates where winter temperatures regularly drop below freezing, leaving the heat pump on at a reduced setpoint (around 62 to 65 degrees) while you're away can be cheaper than letting the home cool to 55 degrees and reheating it later. This is because many heat pumps in cold climates have electric resistance backup heat that kicks in during startup, and that backup is expensive to run. If your system must use backup heat to reheat a cold home, the cost may exceed what you'd spend maintaining a slightly higher temperature all day.
You should also leave the heat pump on continuously if you have water pipes in unheated spaces (like an attic or crawl space) that could freeze, or if you're heating a space where temperature swings could damage contents—a wine cellar, art studio, or room with sensitive equipment. In these cases, the cost of maintaining steady temperature is less than the cost of burst pipes or ruined materials.
If you have a heat pump with a desuperheater that provides hot water, running the system continuously during winter can reduce your water heating costs, since the desuperheater captures waste heat from the heating cycle. This benefit is modest but real in homes that use a lot of hot water.
Using a Thermostat to Automate Temperature Changes
The easiest way to balance comfort and savings is to use a programmable thermostat that automatically lowers the temperature when you're away or asleep, then raises it before you return home. Most programmable models let you set different schedules for weekdays and weekends, so you don't have to adjust manually every time your routine changes.
A smart thermostat (like Nest, Ecobee, or similar models) goes further by learning your patterns and adjusting automatically, or by letting you control the temperature from your phone. If you leave work early or your schedule shifts, you can raise the temperature remotely so the home is comfortable when you arrive, without running the system all day. Smart thermostats also show you how much energy each temperature setting uses, so you can see the real cost of your choices.
Even a basic programmable thermostat pays for itself in a few years through energy savings. Set it to lower the temperature by 7 to 10 degrees during your 8-hour work day and your 8-hour sleep period, and raise it 30 minutes before you wake or arrive home. This schedule avoids the discomfort of coming home to a cold house while capturing most of the savings from turning the system off.
The Risk of Leaving Heat Pump Off Too Long
Turning a heat pump off for a few hours or overnight is safe and saves money. Leaving it off for days or weeks while you're away is riskier, especially in cold climates. If your home cools below 55 degrees, water pipes can freeze, and the cost of repairing burst pipes far exceeds any energy savings. Even if freezing isn't a concern, a very cold home takes much longer to reheat and may trigger expensive backup heating.
If you're leaving for more than a day or two during winter, set the thermostat to 62 to 65 degrees rather than turning the system off completely. This maintains just enough heat to protect pipes and the home structure while using far less energy than keeping the house at 70 degrees. When you return, the home is already warm enough to be comfortable, and you avoid the startup penalty of reheating from a very cold state.
Heat Pump Maintenance and Continuous Operation
Running a heat pump continuously does not wear it out faster than cycling it on and off. Heat pumps are built to run for thousands of hours per year, and the compressor is designed to start and stop many times daily. In fact, some technicians argue that continuous low-speed operation (which modern variable-speed heat pumps can do) is gentler on the compressor than frequent full-power startups.
The real maintenance concern is keeping the outdoor unit clear of snow, ice, and debris, regardless of how often the system runs. A clogged outdoor coil reduces efficiency whether the heat pump is on all the time or cycling normally. Change or clean the indoor air filter every 1 to 3 months, and have the system serviced annually by a technician. These steps matter far more to the lifespan of your heat pump than whether you leave it on or turn it off during absences.
Comparing the Cost of Different Schedules
| Schedule | Winter Heating Cost (Relative) | Comfort Level | Best For |
|---|---|---|---|
| Always on at 70°F | 100% (baseline) | Always comfortable | Homes with freeze risk or sensitive contents |
| On at 70°F during day, 65°F at night | 85–90% | Comfortable when home, slightly cool at night | Most households |
| On at 70°F during day, 60°F while away | 75–80% | Comfortable when home, cold start on return | Long work days, mild climates |
| Off during day, on at night | Varies widely | Uncomfortable during day, risk of freeze | Not recommended |
These percentages are approximate and depend on your climate, home insulation, and how long the system runs each day. A well-insulated home in a mild climate may see savings of 20 to 30 percent by lowering the temperature 10 degrees for 8 hours. A poorly insulated home in a very cold climate may see savings of only 5 to 10 percent, because the heat pump must work harder to reheat afterward.
Frequently Asked Questions
Does turning a heat pump on and off damage it?
No. Heat pumps are designed to start and stop many times per day without damage. The compressor is built for thousands of startup cycles. Turning the system off during absences or at night is a normal operating pattern and does not shorten the equipment's lifespan.
How long does it take a heat pump to heat a cold home?
A heat pump typically reaches steady state (stable operation at your target temperature) within 15 to 30 minutes of startup. If you've lowered the temperature to 60 degrees while away, it may take 45 minutes to an hour to reheat to 70 degrees, especially in very cold weather. This is why programmable thermostats that raise the temperature 30 minutes before you arrive are useful.
Will my heat pump use backup heat if I turn it off and restart it?
It may, depending on how cold your home gets and how cold it is outside. If the outdoor temperature is below 35 to 40 degrees and your home cools significantly, the system may use electric resistance backup heat during the reheating phase. This is expensive, so in cold climates it's better to lower the temperature to 62 to 65 degrees rather than turning the system off completely.
Is it cheaper to leave a heat pump on low all day or turn it off and reheat?
For absences of 8 hours or longer, turning the system off (or lowering it significantly) almost always costs less than running it continuously. The energy saved by not heating an empty home far exceeds the startup penalty. For absences of 1 to 2 hours, the savings are small or nonexistent, so leaving the system on may be simpler.
Can I leave my heat pump off all winter if I'm away for a month?
Not safely in cold climates. Water pipes can freeze at temperatures below 55 degrees, and repairing burst pipes costs thousands of dollars. Set the thermostat to 62 to 65 degrees before you leave, or ask a neighbor to check the home and adjust the temperature if needed. The cost of heating an empty home for a month is far less than the cost of water damage.