Best Thermostat Settings for a Heat Pump With Auxiliary Heat

The best heat-pump setting is the lowest winter temperature—or highest summer temperature—that keeps your household comfortable without forcing long, unnecessary recovery cycles. There is no single magic number for every home.

A practical starting point is 68°F in heating mode and 78°F in cooling mode, then adjust one degree at a time. Those numbers are starting points, not efficiency guarantees. Your climate, humidity, insulation, electricity rate, equipment, and comfort needs matter more than copying another household’s schedule.

For many heat pumps, a steady setting or a small setback works better than a dramatic temperature swing. Large winter setbacks can call for electric-resistance auxiliary heat during recovery, which may erase some of the energy saved while the house was cooler.

Quick settings to try

Treat these as an experiment. Change one setting, observe several comparable days, and use thermostat runtime plus utility data rather than judging from one unusually hot or cold day.

Why heat pumps respond differently to setbacks

Heat pumps move heat rather than make it directly. Many modern systems run for long periods at a low output to maintain an even indoor temperature efficiently. A deep setback creates a large gap between room temperature and the new setpoint, so the thermostat may call for a higher compressor stage or auxiliary heat.

The Department of Energy says a 7°F–10°F setback for eight hours can save energy in many homes, but it also notes that ordinary programmable thermostats have not traditionally been recommended for heat pumps. A heat-pump-aware thermostat can make setbacks more practical by recovering gradually and limiting inefficient auxiliary-heat use.

That distinction matters. A setback strategy that works well with a furnace is not automatically the best strategy for a heat pump with electric resistance backup.

Use a steady setting before adding a schedule

Start with a stable setpoint for three to seven days. This gives you a baseline for comfort, compressor runtime, auxiliary-heat use, and energy consumption.

Then make small changes:

1. Reduce the winter setpoint by 1°F or raise the summer setpoint by 1°F.
2. Keep the new setting for several days with similar weather.
3. Note comfort, humidity, and auxiliary-heat indicators.
4. Compare daily energy use only after accounting for weather and rate changes.
5. Stop when the comfort tradeoff is no longer worthwhile.

Avoid repeatedly turning the thermostat up several degrees because a room feels cold. A higher setpoint does not make the heat pump produce heat faster; it may simply keep it running longer or bring on backup heat sooner.

Keep winter setbacks small

For a heat pump with electric auxiliary strips, begin with no setback or a 2°F–3°F setback. If the thermostat supports adaptive or smart recovery, schedule the desired arrival temperature, not a last-minute jump.

Watch what happens during recovery. Brief auxiliary operation during severe cold or defrost can be normal. Auxiliary heat that appears every morning in mild weather deserves a closer look at the schedule, thermostat configuration, outdoor lockout settings, or system performance.

Do not copy an outdoor auxiliary lockout temperature from the internet. The correct control point depends on the heat pump’s capacity data, the home’s heating load, the backup heat type, local design temperature, electricity and fuel rates, and the installer’s control strategy.

Know the difference between auxiliary and emergency heat

Auxiliary heat is backup heat that the thermostat can call automatically when the heat pump needs help, including during some recovery or defrost conditions. Depending on the system, it may be electric resistance heat or a furnace in a dual-fuel setup.

Emergency heat is a manual operating mode intended for a heat-pump failure or another condition described by the equipment manufacturer. It usually disables the outdoor heat-pump compressor and relies on backup heat.

Emergency heat is not a turbo button. Leaving it on when the heat pump is functional can increase operating cost and hide a problem that needs diagnosis. If the outdoor unit is damaged, iced abnormally, making unsafe noises, or not operating, follow the manufacturer’s instructions and call a qualified technician.

Handle cooling and humidity together

In cooling mode, begin near 78°F and move toward your comfort point. A bigger setpoint is not always better if the house becomes humid.

Variable-speed heat pumps may use long, low-output cycles to improve comfort and moisture removal. Aggressive schedule changes, incorrect fan settings, or an oversized system can reduce dehumidification. If indoor humidity remains high, do not compensate by making extreme thermostat changes; ask the installer to review airflow, equipment staging, controls, drainage, and system sizing.

Use Auto fan mode unless the equipment manufacturer or installer recommends otherwise. A continuously running indoor fan can re-evaporate moisture from a wet cooling coil in some systems.

Check five thermostat configuration items

Some settings belong in the installer menu. Record the current values before changing anything, and involve the installer when a setting affects staging or equipment protection.

• System type: The thermostat must know it controls a heat pump, not a conventional furnace and air conditioner.
• Reversing valve: The O/B setting must match the equipment. An incorrect setting can produce heating in cooling mode or the reverse.
• Heat stages: Compressor and auxiliary stages must match the installed system and wiring.
• Dual-fuel logic: A furnace backup usually needs different staging logic than electric heat strips.
• Compressor protection: Minimum outdoor temperature, cycle timing, and manufacturer limits should follow the equipment documentation and system design.

Proprietary communicating heat pumps may need the manufacturer’s controller to preserve modulation, diagnostics, humidity functions, and warranty support. ENERGY STAR advises buyers of high-efficiency equipment to consider a controller from the same manufacturer.

When settings are not the real problem

Call for service if the system cannot maintain a reasonable setpoint, auxiliary heat runs for long periods in mild weather, energy use changes sharply without a rate or weather explanation, or the outdoor unit develops heavy persistent ice.

Also check the simple maintenance items in our heat-pump maintenance guide: a correctly fitted filter, clear supply and return registers, and unobstructed outdoor airflow. Do not open electrical panels, handle refrigerant, or bypass equipment safeties.

If the system was recently installed, compare its operation with the commissioning and handoff records and review how the installed heat-pump size was selected. A thermostat cannot correct undersized wiring, poor airflow, incorrect refrigerant charge, a bad equipment match, or a system that was never configured for the house.

A seven-day tuning plan

Use this bounded process instead of changing several controls at once:

• Days 1–3: Hold one comfortable temperature and record outdoor weather, runtime, and auxiliary-heat indications.
• Days 4–5: Try a 2°F overnight setback with heat-pump-aware recovery.
• Days 6–7: Compare comfort and daily kilowatt-hours with similar-weather baseline days.
• Afterward: Keep the schedule only if it improves the result. Otherwise return to the steady setting.

The best setting is the one that produces stable comfort with the least unnecessary backup heat—not the most aggressive schedule.

Bottom line

Begin with a steady comfortable setting, then test small changes one at a time. If auxiliary use remains high, follow the high electric-bill diagnostic guide before buying a replacement control; then use the smart thermostat comparison only if compatibility or recovery logic is the real gap.

Frequently asked questions

Should a heat pump run all night?

It can be normal for a variable-speed or properly sized heat pump to run for long periods, especially in cold weather. Long runtime alone is not proof of a fault. Watch whether the home holds temperature, auxiliary heat behaves as designed, and energy use remains reasonable for the weather.

Is 68°F mandatory in winter?

No. It is a useful starting point. Adjust for health, age, clothing, humidity, building conditions, and personal comfort.

Why does auxiliary heat appear after I raise the thermostat?

A large setpoint increase can tell the thermostat that the compressor alone will not recover quickly enough. Heat-pump-aware recovery may start earlier and raise the temperature gradually to avoid or reduce that call.

Should I turn on emergency heat during a cold snap?

Not merely because it is cold. A functioning heat pump and thermostat should call backup heat automatically when needed. Use emergency mode only under the manufacturer’s or technician’s direction when the heat-pump side cannot operate safely.

Sources and editorial notes

• U.S. Department of Energy: Home Upgrades — supports the general setback guidance and the special caution for heat-pump thermostats.
• ENERGY STAR: Smart Thermostats — supports compatibility checks, manufacturer controls for high-efficiency equipment, and certified smart-thermostat functions.
• ENERGY STAR: Smart Thermostats Key Product Criteria — supports energy-use feedback, scheduling, and reporting of resistance-heat utilization.
• U.S. Department of Energy: Connected Thermostat Use Cases (PDF) — supports weather-adaptive recovery and reducing auxiliary-heat use.
• This article provides general operating guidance, not model-specific commissioning instructions. Equipment manuals and the installed system design control.