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Heat pumps are fast becoming one of the most talked-about, low-carbon alternatives to gas boilers in UK homes. Very simply, they work by extracting heat from the air or ground outside and using it to warm your home and hot water. Unlike a boiler, where the temperature can yo-yo, a heat pump will keep your home at a constant temperature and running costs can be lower.
As interest grows, companies such as Octopus Energy have played a role in bringing heat pumps into the mainstream, offering installation services for homeowners looking to switch. But despite their rising popularity, heat pumps are still widely misunderstood. From concerns about cold weather performance to expensive installation, a number of myths continue to circulate. Here are some of the common misconceptions and the reality behind them.
“Heat pumps don’t work in cold weather”
Not true. Heat pumps are designed to extract heat from the air even when temperatures drop as low as -20C.
Admittedly, on the rare days it does get cold in the UK, a heat pump will need to work harder and use more electricity to capture and compress that heat. However, it still delivers more heat energy than the electricity it consumes. A heat pump typically produces around three to four units of heat for every one unit of electricity used.
By comparison, a gas boiler generates heat by burning fuel, with some energy lost through combustion and flue gases and typically operates at around 85 to 95 per cent efficiency.
“Heat pumps have to be on south-facing walls”
A myth. Heat pumps can in fact be installed on any external wall, provided there is enough space and airflow around the unit. Other factors such as pipe runs, noise considerations and access for maintenance are far more important than the direction the unit faces.
“Heat pumps can replace air conditioning in heatwaves”
Yes, and no; it depends on the type of heat pump you have. Most heat pumps installed in UK homes are air-to-water systems; some models can offer cooling as well as heating, but it is not a standard feature.
If you're looking for both heating and air conditioning, an air-to-air heat pump is the better option, although they are less commonly fitted in the UK. If cooling is a priority, it's worth discussing the best heat pump for your home with your installer.
“Heat pumps are too expensive to buy and run”
While gas is admittedly cheaper than electricity, heat pumps are highly efficient, often producing three to four units of heat for every one unit of electricity used.
This means that, over time, they can deliver lower overall running costs than a new gas boiler, particularly when paired with off-peak electricity tariffs or combined with solar panels. According to a survey by Octopus Energy, its customers saved £219 a year with a heat pump combined with a Cosy Octopus tariff compared to heating the same home with a gas boiler on a standard tariff.
Under the government’s Boiler Upgrade Scheme, installing a heat pump has also become a lot more affordable. This grant can help reduce upfront costs significantly. For example, for Octopus Energy, the typical installed price comes in at around £4,459 after the grant, compared with a UK average of approximately £5,931. Some high street banks are also currently offering loans and cashbacks.
“Installing a heat pump will require a whole new central heating system”
Not true. In many cases, heat pumps can be retrofitted into most existing homes without extensive plumbing or replacing the entire central heating system.
However, some upgrades may be needed to help the system operate efficiently. Because heat pumps typically run at lower flow temperatures than gas boilers, they produce cooler water for radiators. In some homes, existing radiators may need to be replaced with larger ones, which provide a greater surface area to deliver the same amount of heat. Some properties may also require sections of pipework to be upgraded if the existing pipes are too small or in poor condition.
It is also often claimed that homes need to be "Passivhaus airtight" for a heat pump to work effectively. This is a myth. While draughtproofing will improve efficiency, heat pumps can work well in many existing homes. Simple improvements, such as adding seals to windows and doors and upgrading your loft insulation, can make a noticeable difference to performance too.
“Heat pumps don’t get homes warm enough”
Heat pumps typically heat homes to the same levels as gas boilers (around 18C to 21C), but they work differently by delivering steady, lower-temperature heat over longer periods rather than short bursts of very hot heat. It means you don’t have to keep jumping up and down fiddling with your thermostat to get the perfect temperature as your home stays warm constantly.
“Heat pumps are noisy”
Gone are the days of loud, bulky units – modern air source heat pumps are sleeker, more compact and much quieter. Typically, a heat pump runs at about 40 decibels, similar to the hum of a refrigerator, though it can rise to around 60 decibels on colder days when it needs to work harder to extract heat from the air.
Perhaps because they are installed outside, the perception that heat pumps are noisy has plagued them since their inception. However, a 2025 survey by the National Endowment for Science, Technology and the Arts (Nesta) found that even multiple air source heat pumps operating in residential areas at the same time were “unlikely to significantly exceed the noise of a single unit, even under worst-case scenario assumptions”.
There are also strict planning and noise regulations governing their location (no louder than 42 decibels within one metre of a neighbour’s door or window). A lack of understanding about how to operate heat pumps properly has also been blamed - turning them off then on (it is recommended to keep a pump on year-round) can also create more noise.
Manufacturers are also continuing to improve performance and acoustics, with some newer models designed to run even more quietly. For example, Octopus Energy’s Cosy heat pump includes a ‘Hush Mode’ to reduce noise.
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