A heat pump is an air conditioner that works in both directions — cooling in summer by moving heat outside, heating in winter by extracting heat from outside air and moving it inside. The key insight most people miss: even cold outside air contains heat energy. A quality heat pump extracts useful heat from outside air down to -15°C to -25°C, making it an effective heater in almost all climates outside of the Arctic.
The efficiency advantage is the reason heat pumps have become the recommended electrification choice for home heating. A resistive electric heater converts 1 kWh of electricity into 1 kWh of heat (100% efficiency). A quality heat pump converts 1 kWh of electricity into 3–5 kWh of heat (300–500% efficiency, expressed as Coefficient of Performance or COP). This difference makes heat pumps 3–5× cheaper to run than energy-efficient space heaters and, depending on your grid's carbon intensity, significantly lower-emission than gas heating.
Split system (mini-split): One outdoor unit (compressor) and one or more indoor units (air handlers) connected by refrigerant lines. The most common type for residential use. Single-zone (one indoor unit) for individual rooms or zones; multi-split systems (one outdoor, multiple indoor units) for whole-home heating and cooling without ductwork.
Ducted heat pump: Central unit connected to existing or new ductwork, distributing conditioned air throughout the home. Best for homes with existing duct systems. Less efficient than modern mini-splits but more consistent temperature distribution.
Heat pump water heater: A separate appliance specifically for water heating. See our heat pump hot water guide for details.
Ground source heat pump (geothermal): Uses the stable temperature of the ground (rather than outside air) as the heat source. Higher efficiency than air-source but significantly more expensive to install (requires ground loops or bore holes). Best for new construction or major renovations where installation cost is amortised.
COP (Coefficient of Performance): How many kWh of heating or cooling you get per kWh of electricity input. COP 3.0 means 3 kWh of heat per kWh of electricity. Measured at a specific temperature; drops in very cold conditions. Always check the COP at your typical coldest design temperature, not just the peak rating.
SEER2 (Seasonal Energy Efficiency Ratio): US and some international standard for cooling efficiency over an entire season. Higher is better. Minimum federal standard in the US is SEER2 14; premium systems reach SEER2 20–30+.
HSPF2 (Heating Seasonal Performance Factor): US standard for heating efficiency over an entire heating season. Higher is better. A system with HSPF2 10+ is genuinely high-efficiency for cold climates.
Models: Hyper-Heating INVERTER (H2i) series — MSZ, MXZ, PUZ
Mitsubishi Electric has consistently earned the highest reliability ratings and customer satisfaction scores in the heat pump market across multiple independent surveys. The H2i (Hyper-Heating INVERTER) technology is the benchmark for cold-climate performance — maintaining full heating capacity to -18°C and providing useful heat to -25°C. For any climate that experiences genuinely cold winters, Mitsubishi's cold-weather performance advantage over budget brands is significant. The MXZ multi-zone system allows one outdoor unit to serve 2–8 indoor units — ideal for whole-home coverage without ductwork. Installation is widely available through qualified HVAC contractors globally. Price premium: 20–40% above budget brands. Warranty: 5–12 years depending on model and registration.
Models: Daikin Fit, Emura, Stylish, Perfera series
Daikin is the world's largest HVAC manufacturer and consistently leads on technological innovation. The Daikin Fit's compact side-discharge outdoor unit solves installation space constraints in tight urban settings. The Emura and Stylish series prioritise interior aesthetics — among the best-looking indoor units available. Efficiency ratings are competitive with Mitsubishi at the top-of-range products. Daikin's refrigerant leadership (they were early adopters of R-32, a lower-global-warming-potential refrigerant) reflects a genuine commitment to environmental performance. Price: comparable to Mitsubishi. Warranty: 5–12 years depending on model.
Models: Halcyon, Airstage, J-Series with Hyper Heat
Fujitsu's Hyper Heat technology (marketed as XLTH — Extra Low Temperature Heating) delivers full heating capacity to -15°C and useful heat to -25°C — directly competitive with Mitsubishi's H2i. Independent tests in cold climates consistently show Fujitsu and Mitsubishi as the two strongest performers when outside temperatures drop below -10°C. For homeowners in Canada, Northern Europe, the US Northeast, or any consistently cold climate where other brands reduce capacity significantly in winter, Fujitsu Hyper Heat is the reliable choice. Price: similar to Mitsubishi. Warranty: 5–10 years.
Models: Ultra-Quiet, Climate 5000, IDS series
Bosch's IDS (Inverter Ducted Split) systems offer premium European engineering at pricing typically 15–20% below Mitsubishi and Daikin equivalents. The ultra-quiet outdoor units are among the quietest in the market — meaningful for installations close to bedroom windows or in noise-restricted settings. Cold-climate performance doesn't match Mitsubishi H2i or Fujitsu Hyper Heat at extreme temperatures, but for moderate climates (where winter temperatures rarely drop below -5°C), Bosch represents excellent value at a competitive price. Price: 15–20% below Mitsubishi/Daikin. Warranty: 5 years standard.
Models: Art Cool Gallery, Multi F, LGRED°
LG's LGRED° (Low Ambient Heating) systems provide competitive cold-climate performance (full capacity to -15°C) at pricing typically 10–25% below the Japanese premium brands. The Art Cool Gallery indoor unit — a frame that displays user-chosen artwork — is genuinely distinctive for design-conscious homeowners. LG's global service network is broad, which is an important consideration for warranty support. For moderate climates and budget-conscious buyers who want a quality system without paying the full Mitsubishi premium, LG LGRED° is the recommended choice. Price: mid-range. Warranty: 5–7 years.
Mild climates (minimum temps above 0°C): Any brand including mid-range options performs well. Prioritise efficiency ratings and noise levels. Daikin and Bosch are excellent choices.
Cold climates (regular temperatures to -15°C): Mitsubishi H2i or Fujitsu Hyper Heat are the recommended choices. Their cold-climate performance advantage over standard systems is real and significant for annual heating costs and comfort.
Very cold climates (regular temperatures below -20°C): Mitsubishi H2i and Fujitsu Hyper Heat maintain performance better than any alternatives. Ground source heat pump is worth evaluating for these climates if installation cost can be justified.
Heat pumps are sized in kW of heating/cooling capacity. A correctly sized system runs for longer periods at moderate power rather than cycling on and off at full power — this is more comfortable, quieter, more efficient, and reduces wear. A rule of thumb: 0.1kW per square metre of floor area for moderate climates; 0.15kW/m² for cold climates and poorly insulated homes. A qualified HVAC engineer will do a proper heat load calculation based on your specific home — insulation levels, window area, orientation, and local climate. This calculation is important; don't skip it.