In the winter, a heat pump provides heating by extracting heat from outside a building and moving it inside. In the summer, it can provide cooling by moving heat from indoors to the outside.
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Find out about the different types of heat pumps, how they work and why they could help to tackle climate change.
How a heat pump works
A heat pump uses the same technology as an air conditioner, which cools your home using a refrigerant. The only major difference between an air-conditioner and a heat pump is that a heat pump has a reversing valve, which allows it to also heat your home.
In heating mode, a heat pump works like an air conditioner in reverse; instead of keeping your home cool, it uses the refrigerant to warm your home.
Here’s a step-by-step process of how heat pumps work:
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Heat could be sourced from the air outside or warmth from the ground. This is blown or pumped over the heat exchange surface of the exterior part of the heat pump.
- This heat is warm enough to cause the refrigerant liquid in the heat pump to evaporate and turn into a gas.
- This gas is then moved through a compressor, which increases the pressure, causing its temperature to rise.
- The gas (now heated) is passed over the internal heat exchange surface. This heat can then be either blown around the home's interior or transferred into a central heating or hot water system.
- As the heat is transferred into the home, the gas falls in temperature, causing it to return to a liquid state.
- The cycle of reverse refrigeration repeats until your home reaches the required temperature setting on your thermostat.
If heat pumps obtain their heat from outside, how do they provide heat on a cold day?
Even when it’s very cold outside, some heat energy still exists. Heat pumps are effective at taking this heat energy from the ground or air around a building and using it to provide heat for your home or business.
For heat pumps to work at their best, it’s also important that the building has good energy efficiency installed, such as effective insulation.
What different types of heat pumps are there?
There are different types of heat pumps: air-source and ground-source.
Heat pumps can also be paired with fossil fuel gas furnaces; these systems are often referred to as hybrid heat pumps.
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How does an air-source heat pump work?
- Air-to-water heat pumps take heat from the outside air and feed it into your wet central heating system (similar to existing gas central heating). As the heat produced is cooler than that from a conventional furnace or boiler, you may need to install larger radiators or underfloor heating in your home to make the most of it. Air-to-water heat pumps may be best suited to new-build properties or those that are energy efficient.
- Air-to-air heat pumps take heat from the outside air and feed it into your home through fans. This type of system can be used for heating but can’t produce hot water.
How does a ground-source heat pump work?
How does a hybrid heat pump work?
Why are heat pumps important in helping reach net zero?
Around 40% of global emissions come from buildings and most of these result from the ways we heat our homes and businesses.
To reach net zero carbon emissions and tackle climate change, we need to switch from heating that relies on high-carbon fuels to cleaner, low- or zero-carbon alternatives.
Heat pumps will help to achieve this for two main reasons:
- Heat pump systems are designed to extract a greater amount of heat energy from the surrounding environment than the energy they consume to create heat. They can produce two to three times more heat output than they consume in electricity input.
- As more and more electricity is generated from renewable energy sources like solar or wind power, the electricity used to power heat pumps is itself becoming cleaner.
Minisplit Heat Pumps
Minisplit heat pumps, a ductless air-source variant, are highly effective for homes without ductwork, offering an efficient alternative to baseboard heating. These systems can reduce energy costs significantly, especially for zone heating. While other configurations, such as air-to-water heat pumps, exist, minisplits are the most common solution for homes with radiator heating in regions like New England and the Mid-Atlantic, where ducted systems are less prevalent.
Additional Context:
- In warmer climates (zones 1-4), about 60% of homes rely on furnaces, while heat pumps are used in 15%-25% of homes, especially mobile homes. Approximately 12%-25% of homes have systems without ductwork, which makes minisplits a viable option (Building America Solution Center) (ENERGY STAR).
- In colder climates (zones 5-7), furnaces are indeed the dominant heating system, used in approximately 63% of homes. Heat pumps, although more efficient in some cases, account for only about 3% of the primary heating systems in these regions. Additionally, around 32% of homes in these areas lack ductwork, making ductless solutions like minisplit heat pumps a practical option for those looking to switch to more energy-efficient systems (EnergySage) (EnergySage) (Bob Vila).
For homes with existing ductwork, replacing a furnace with a heat pump or installing a hybrid system is often easier. However, for homes without ductwork, minisplit systems are generally the best retrofit option. For new home construction, various configurations are available, but cost and specific climate conditions usually influence the choice.
Several innovations are improving the performance of heat pumps:
Staged or Multi-Speed Compressors
- Staged or multi-speed compressors let heat pumps operate close to the heating or cooling capacity needed at any outdoor temperature.
- These systems save energy by reducing on/off operation and compressor wear.
- Inverter-driven systems can modulate their speed/capacity at near-infinite degrees between low and high settings, running efficiently and maintaining consistent comfort.
Variable-Speed or Dual-Speed Motors
- Most newer models of heat pumps and furnace blowers are equipped with electrically commutated motors (ECM) or variable-speed or dual-speed motors on their indoor fans, outdoor fans, or both.
- Variable-speed controls for these fans keep the air moving at a comfortable velocity, minimizing cool drafts, maximizing electrical savings, and reducing noise and disruption.
Desuperheater
- Some high-efficiency heat pumps are equipped with a desuperheater, which recovers waste heat from the heat pump's cooling mode and uses it to heat water.
- A desuperheater-equipped heat pump can heat water 2 to 3 times more efficiently than an ordinary electric-resistance water heater.
Dual-Fuel or Hybrid Systems
Dual-fuel or hybrid systems combine the efficiency of a heat pump with the reliability of a gas furnace. This combination allows the heat pump to handle most of the heating needs in milder weather, while the furnace takes over during colder temperatures.
How It Works:
- Energy Efficiency: During warmer months, the heat pump efficiently heats and cools your home. When temperatures drop, the system automatically switches to the gas furnace, which is better suited for cold weather.
- Shared Ductwork: Both systems typically use the same ductwork, making it a straightforward installation if you’re upgrading from a traditional furnace and air conditioning setup.
- Widely Available: Commonly found in regions like the Mid-Atlantic, dual-fuel systems are easy to implement and help homeowners reduce electricity use in cold climates while maintaining comfort year-round.
This setup is a great option for homeowners looking to maximize energy savings while ensuring reliable heating in colder weather.
If you are looking for more details, kindly visit residential heat pump manufacturer.
Cold Climate Heat Pumps
- Cold climate heat pumps are designed to perform in temperatures as low as 5°F.
- If you live in a region where temperatures regularly dip below freezing in winter months, consider looking for a system with an ENERGY STAR Cold Climate label.
- Learn more about ENERGY STAR Cold Climate heat pumps.