Heat pump amperage depends on size, outdoor temperature, and whether it's heating or cooling

A typical residential heat pump draws between 15 and 25 amps during normal operation, though the actual number shifts based on how hard the system is working. A small unit cooling a single room might use 10 to 15 amps, while a larger whole-house system can pull 30 to 50 amps or more. The amperage also changes throughout the day—it spikes when the compressor first starts and when the system switches between heating and cooling modes.

The reason amperage matters is that it tells you whether your electrical panel can handle the heat pump without overloading. If your home has an older 100-amp service and you're adding a large heat pump, you may need to upgrade the panel or circuit breaker. Knowing the actual amp draw also helps you understand your electric bill and whether the system is running efficiently.

Key Takeaways

  • Most residential heat pumps use 15 to 25 amps during steady operation, with larger units reaching 30 to 50 amps.
  • Amperage increases when outdoor temperature drops below freezing because the system works harder to extract heat from cold air.
  • The compressor draws the most power; auxiliary heating elements (if present) add significant amps on top of that.
  • Your electrical panel must have enough spare capacity to handle the heat pump's peak amperage without tripping breakers or requiring an upgrade.

How to find your heat pump's amp rating

The most reliable way to know your heat pump's amperage is to check the nameplate—a metal or plastic label attached to the outdoor unit. Look for "RLA" (running load amps) or "FLA" (full load amps). RLA is the number you want because it reflects what the compressor actually draws during normal cooling or heating. FLA is a worst-case figure and is usually higher.

If you can't read the nameplate or it's missing, check your equipment manual or the manufacturer's website using your model number. You can also call an HVAC technician to measure the actual amperage with a clamp meter while the system runs. This takes about 15 minutes and costs $75 to $150, but it gives you a precise number for your specific conditions.

Why amperage changes with outdoor temperature

When it's cold outside, your heat pump has to work much harder to pull heat from the frigid air. As outdoor temperature drops, the compressor runs longer and draws more amps. Below 32°F, many heat pumps switch on auxiliary electric heating strips, which consume an additional 5 to 15 amps on their own. This is why your electric bill jumps during winter heating season.

In cooling mode, the opposite happens. On a mild 70°F day, the compressor may cycle on and off frequently and draw fewer amps than on a scorching 95°F afternoon when it runs almost continuously. The system is designed to modulate—to ramp up or down—based on how much heating or cooling is needed, so the amp draw is never truly constant.

Understanding peak amperage versus running amperage

When a heat pump compressor first starts, it draws a brief surge of current called inrush amperage or locked rotor amps. This spike can be two to three times the running amperage and lasts only a fraction of a second. A unit with a 20-amp running draw might spike to 40 or 50 amps at startup. This is normal and why circuit breakers are sized with headroom.

Your electrical panel and breaker must be rated for both the running amps and the inrush. If a breaker is too small, it will trip repeatedly even though the system is working correctly. An electrician sizes the breaker by adding 25 percent to the RLA figure, which accounts for the startup surge and gives a safety margin. This is why a heat pump with a 20-amp RLA typically gets a 25-amp breaker, not a 20-amp one.

When you need an electrical panel upgrade

If your home's main electrical service is 100 amps and you're adding a heat pump that draws 25 to 30 amps, you may have enough spare capacity. But if you already have a water heater (4,000 to 5,000 watts), an electric range (8,000 to 12,000 watts), and other large loads, the panel could be overloaded. An electrician can calculate your total demand and tell you whether an upgrade is necessary.

A panel upgrade typically costs $1,500 to $3,000 and involves replacing the main breaker and service lines. It's not a small job, but it's essential if the heat pump would push your home over its electrical capacity. Some utility companies offer rebates for panel upgrades paired with heat pump installation, so ask your installer whether you may have access to.

How to reduce heat pump amperage draw

You can't change the amp rating of the unit itself, but you can reduce how often it runs at full capacity. Setting your thermostat a few degrees lower in winter or higher in summer means the compressor cycles less frequently and draws fewer amps overall. Proper insulation, weatherstripping, and ductwork sealing also help the system reach your target temperature faster, so it doesn't have to run as long.

Keeping the outdoor unit clean and free of debris improves airflow and efficiency, which means the compressor doesn't have to work as hard. A clogged filter in the indoor unit has the same effect. If your system has auxiliary heating strips, they are usually controlled by a thermostat setting—raising the heating setpoint by 1°F can set up the strips, so keeping the setpoint moderate reduces their use and saves amps.

What amperage means for your electric bill

Amperage alone doesn't determine your bill; wattage does. To convert amps to watts, multiply amps by voltage (usually 240V for a heat pump): 20 amps × 240V = 4,800 watts. If your heat pump runs for 8 hours a day at 4,800 watts, that's 38.4 kilowatt-hours per day. At an average rate of $0.14 per kilowatt-hour, that's about $5.40 per day or $160 per month.

The actual bill varies by your local electricity rate, how often the system runs, and seasonal changes. Heat pumps are generally more efficient than electric resistance heating, so even though the amperage seems high, the monthly cost is often lower than what you'd pay for a furnace or baseboard heaters. An HVAC contractor can estimate your operating cost based on your local rates and climate.

Frequently Asked Questions

Can I run a heat pump on a 15-amp circuit?

No. A 15-amp circuit is designed for small appliances and lights, not for a compressor that draws 15 to 25 amps. Heat pumps require a dedicated circuit sized for their full load amperage plus 25 percent. Attempting to run one on an undersized circuit will trip the breaker repeatedly and damage the equipment.

Does a heat pump use more amps in heating or cooling mode?

It depends on outdoor temperature. In cooling mode on a hot day, the system works hard and draws high amps. In heating mode on a very cold day, it works even harder and may set up auxiliary heating strips, drawing even more amps. Mild weather in either season means lower amp draw because the compressor doesn't have to run as long.

What's the difference between RLA and FLA?

RLA (running load amps) is what the compressor actually draws during normal operation. FLA (full load amps) is a theoretical maximum used for motor design and is usually higher. Use the RLA number when sizing your electrical panel and breaker, because it reflects real-world performance.

Will adding a heat pump require me to upgrade my electrical panel?

Not always. If your home has a 200-amp service and low overall demand, a 25-amp heat pump may fit without upgrades. If you have a 100-amp service and several large appliances, an upgrade may be necessary. An electrician can assess your panel and tell you what's needed before installation begins.

Why does my heat pump breaker trip when it starts up?

The breaker may be undersized for the inrush amperage. When the compressor starts, it draws a brief surge that can be two to three times the running amps. If the breaker is rated too low, it trips. Have an electrician check the breaker size and replace it with one rated for at least 125 percent of the RLA.