How Many Amps a Heat Pump Uses: Guide to Electrical Consumption

A heat pump’s amperage varies by size, type, and operating conditions; understanding running amps, locked-rotor amps, and service requirements helps homeowners, electricians, and contractors size circuits and manage energy costs. This guide explains typical amp ranges, how to calculate load, and practical tips to ensure safe, efficient operation.

Heat Pump Type	Typical Running Amps (A)	Typical Breaker Size
Mini-Split (1–2 Ton)	6–15 A	15–20 A
Split System (2–3 Ton)	10–20 A	20–30 A
Central Heat Pump (3–5 Ton)	20–40 A	30–60 A
Large Commercial Units	40–100+ A	60–200+ A

How Heat Pumps Draw Current

Heat pumps move heat by running compressors, fans, and control electronics. The compressor is the primary electrical load. Running amps represent steady-state current during normal operation, while starting or locked-rotor amps are higher brief surges when the compressor starts. Fans and auxiliary heaters add additional continuous or intermittent load.

Factors That Affect Amps Drawn

Several variables influence how many amps a heat pump uses. Key factors include:

• Capacity (Tonnage): Larger tonnage units require more power. A 1-ton mini-split draws far less than a 5-ton central unit.
• Compressor Type: Scroll, rotary, and inverter-driven variable-speed compressors have different current profiles. Inverter (variable-speed) models often have lower start-up surges and smoother running amps.
• Voltage: Most residential heat pumps operate on 240V in the U.S.; higher voltage reduces current for the same power.
• Efficiency (SEER/HSPF): Higher-efficiency systems can reduce runtime and sometimes lower amperage due to improved components.
• Ambient Conditions: Extreme cold or heat increases load, especially when auxiliary electric resistance heat engages.

Typical Running Amps By Unit Type And Size

The following ranges reflect common residential equipment on 240V circuits. Exact values depend on model specifications.

Unit Type	Capacity	Typical Running Amps
Mini-Split/Wall-Mounted	9,000–24,000 BTU (0.75–2 Ton)	6–15 A
Small Split System	18,000–36,000 BTU (1.5–3 Ton)	10–20 A
Standard Central Heat Pump	3–5 Ton	20–40 A
Large Residential/Light Commercial	5–10 Ton	40–80 A
Commercial Rooftop Units	Large Capacities	80–200+ A

Understanding Nameplate Ratings And Spec Sheets

Each heat pump has a nameplate and an electrical data section in its manual that lists rated running current (RLA), locked-rotor amps (LRA), and minimum circuit ampacity (MCA). RLA is the expected running current; LRA is the maximum short-term starting current. MCA indicates the minimum conductor size and influences breaker selection.

Calculating Amps From Power And Voltage

If only power (in watts or BTU) is known, amps can be estimated. For single-phase 240V equipment, amps = watts ÷ volts. For example, a 6,000 W compressor at 240V draws ~25 A. Convert BTU to W (1 BTU/h ≈ 0.293 W) for capacity-based estimates, keeping in mind motor efficiency.

Starting Current Versus Running Current

Start-up surges can be 3–6 times the running amps for fixed-speed compressors; inverter-driven compressors avoid such large spikes. Circuit breakers accommodate short surges if sized correctly, but excessive starting current can trip undersized breakers or cause voltage drops.

Breaker And Conductor Sizing

National Electrical Code (NEC) rules guide breaker and conductor sizing for heat pumps. Electricians use MCA plus load diversity and service calculations. Common practices include:

• Size conductors to at least the MCA.
• Choose a breaker to handle continuous load (typically 125% of continuous currents, per NEC for some applications).
• Account for auxiliary electric heat separately; it is treated as a continuous load and increases required breaker size and service capacity.

Example Calculations

Example 1: A 3-ton heat pump with a 240V nameplate showing RLA 18 A and MCA 26 A. The circuit should use conductors rated ≥26 A and a breaker sized per local code—often 30 A.

Example 2: A 2-ton mini-split with RLA 10 A and LRA 55 A on 240V. Running breaker selection might be 20 A with conductors sized per MCA; the LRA does not require a breaker equal to that value since it’s a short-duration event.

Impact Of Auxiliary Electric Heat

Heat pumps sometimes include or require electric resistance backup heat (strip heaters). These elements can draw large currents: a 5 kW strip heater at 240V draws ~21 A, while a 10 kW heater draws ~42 A. When auxiliary heat cycles on, total system amperage can more than double.

Amps And Energy Use (kWh)

Amps alone don’t show energy consumption. To estimate kWh, calculate power: watts = volts × amps. For example, a heat pump drawing 25 A at 240V consumes 6,000 W (6 kW) when running. Running 6 kW for one hour equals 6 kWh. Efficiency measured by COP or SEER/HSPF affects energy per unit heating or cooling delivered.

Variable-Speed And Inverter Technology

Inverter-driven heat pumps modulate compressor speed to match load. They tend to have lower average amperage and smaller startup surges, improving part-load efficiency and reducing peak demand. This often translates to lower monthly energy bills and fewer nuisance trips from breakers.

Common Misconceptions

• Assuming a single amp value: Heat pump amps vary by runtime and conditions; nameplate values are the correct reference.
• Confusing breaker size with running amps: Breakers protect wiring and tolerate short transients; they are usually larger than running current.
• Ignoring auxiliary heat: Electric resistance backup can be the largest single draw during cold starts.

How To Measure Actual Amps

Licensed electricians use clamp meters or multimeters on live conductors to measure running and startup current. For safety and code compliance, professional measurement is recommended before changing breakers or service. Recording amps across different conditions (defrost cycle, low ambient, high load) gives a more accurate picture.

Service Panel And Home Capacity Considerations

Older homes with 100 A service may struggle to add a large heat pump plus other loads. A whole-house heat pump installation often requires a service upgrade to 200 A or more, depending on HVAC size, electric resistance heat, and other household loads. Load calculations per NEC determine necessary service capacity.

Selecting The Right Heat Pump To Minimize Amps

Factors that reduce amperage and peak demand include:

• Choosing an inverter variable-speed model.
• Properly sizing equipment to avoid oversized compressors and short cycling.
• Adding thermal improvements (insulation, air sealing) to reduce demand.
• Using heat pump models with high COP at local design temperatures.

Safety And Code Compliance

All electrical work must comply with NEC and local codes. Mis-sized breakers, undersized conductors, or DIY wiring can cause hazards. Always consult a licensed electrician or HVAC professional for circuit sizing, service upgrades, and to interpret manufacturer MCA and RLA values.

Practical Tips To Reduce Peak Amps And Costs

• Install a soft-start device or choose inverter models to limit start-up surge.
• Use staggered scheduling for electric water heaters or other large loads.
• Consider demand response programs or time-of-use rates to shift operation to off-peak times.
• Maintain equipment—clean coils and filters improve efficiency and may lower amperage.

When To Call A Professional

Call a licensed HVAC technician or electrician when planning new installations, upgrading service, or troubleshooting tripped breakers linked to HVAC. Professionals use manufacturer data and NEC rules to safely size conductors and breakers and can measure amps to validate performance.

Quick Reference: What To Expect For Residential Installations

Scenario	Typical Running Amps	Breaker Size
Small Mini-Split (wall)	6–12 A	15–20 A
Medium Split System (2–3 Ton)	10–20 A	20–30 A
Large Central Heat Pump (4–5 Ton)	25–40 A	30–60 A
Electric Backup Heat (strip)	21–42 A (per 5–10 kW)	30–60 A

Key Takeaways

Amps Depend On Unit Size, Type, And Conditions. Use manufacturer RLA and MCA values for accurate sizing. Inverter heat pumps lower average amps and startup surge. Auxiliary electric heat significantly increases total current. Consult professionals for measurement and electrical work to ensure safety and compliance.

For specific amp values and circuit recommendations, review the heat pump’s electrical specifications and engage a licensed electrician to perform load calculations and installation. Proper planning prevents nuisance trips, reduces energy costs, and ensures safe operation.