Introduction
Cutting our reliance on fossil fuel heating is central to the UK’s net zero pathway. Government policy still points to 600,000 heat-pump installations per year by 2028, alongside millions more by the mid-2030s, but today’s pace remains well short of that ambition.
There is progress. The Boiler Upgrade Scheme (BUS) grant rose to £7,500 and has seen sustained growth: by 31 August 2025, Ofgem reports 94,633 applications and 61,816 vouchers redeemed (over £423mn paid out). Planning has also eased in England: from 29 May 2025, most homes can install air-source heat pumps under permitted development, with the one-metre boundary rule removed and the allowable unit size increased—reducing friction for space-constrained properties,
At the same time, hesitancy is real. DESNZ’s Spring 2025 Public Attitudes Tracker shows awareness rising but a growing share of people now say they’re unlikely to install a heat pump in the near term. Nesta’s consumer segmentation highlights distinct audiences with different barriers, from up-front cost and space, to confidence in performance and installers, underscoring the need for practical, household-specific solutions.
This is where compact thermal storage helps. Pairing a heat pump with a space-saving heat battery unlocks installations in tighter homes, improves hot water comfort, and shifts demand onto cheaper, off-peak tariffs to keep running costs competitive. The combination supports the grid transition too, by flattening peaks as electric heating scales. In the sections below, we draw from the Guardian’s mythbuster series and Carbon Brief’s analysis, and debunk the most common myths surrounding heat pumps, and show how compact thermal storage makes heat pumps work better, for households, installers and the energy system.
Myth 1: Heat pumps are more expensive to run than gas boilers
Heat pumps do come with higher upfront costs compared to gas boilers. In 2025, typical installations average £11,000-£13,200 depending on property size and system design, according to the Energy Saving Trust and MCS. However, with the BUS grant at £7,500, many homeowners now face a net cost much closer to a like-for-like boiler and cylinder replacement.
There is speculation around the running costs too though; the common concern is that heat pumps will overall cost more to run, in terms of energy bills.
However, these costs are offset by reduced operational expenses over time – thanks to the extremely high efficiency (CoP) of heat pumps, producing 2.5-5 units of heat per unit of electricity, meaning they use 3-5x less energy than a gas boiler.
In technical terms, heat pumps with a seasonal coefficient of performance (SCoP) greater than 3 can achieve running costs comparable to those of an 85% efficient gas boiler. A SCoP of 3.2 matches the running costs of a 90% efficient A-rated gas boiler. Compared to an older G-rated boiler, users of heat pumps can save approximately £340 annually.
Additionally, the newly introduced tariffs, such as Cosy Octopus and Heat Pump Plus, make heat pumps with a SCoP below 2.9 significantly more cost-effective than a new gas boiler. Ofgem and the Advertising Standards Authority now require suppliers to be clear these are examples, not guaranteed savings, so expectations remain realistic.
While energy prices fluctuate, Ofgem’s 2025 price cap adjustments continue to narrow the gap between gas and electricity, and long-term government policy aims to keep low-carbon electricity more affordable than fossil fuels.
Myth 2: Heat pumps don’t work in older homes
In Britain, there are concerns that heat pumps may not be effective in older homes, such as Victorian and pre-WWII properties.
The Energy and Utilities Alliance, representing gas boiler manufacturers, suggested that up to 54% of British households could face challenges in replacing gas boilers with heat pumps due to factors like poor insulation or limited space. Critics argue that heat pumps may struggle to efficiently heat poorly insulated homes.
In reality, millions of buildings worldwide, regardless of age, have successfully been fitted with heat pumps. The UK government’s boiler upgrade scheme, which provides grants of up to £7,500 towards an air source heat pump. Planning rules for installing heat pumps have also been relaxed in 2025.
Research from the Energy Systems Catapult (ESC), an independent UK organisation, challenges the idea that heat pumps are unsuitable for certain homes. In an Electrification of Heat project involving up to 750 properties across the UK, including Victorian terraces and 1960s flats, the ESC found that heat pumps could be successfully installed in all types of homes. The ESC report dispelled the myth that older homes cannot accommodate heat pumps, supported by data and real-world experience.
In another long-term study, Fraunhofer Society Study, cited by the Guardian, 300 heat pumps were monitored over 20 years in buildings aged between 15 and 150 years. The findings revealed that air-source heat pumps achieved an average seasonal performance rating of 3.1, meaning they were over three times more efficient than gas boilers, even in older, partially or fully refurbished buildings. With the new planning rules introduced in May 2025, it has also become easier to site external heat pump units, since the old one-metre boundary restriction has been removed and larger units up to 1.5 m³ are now permitted without full planning permission. However, the studies mention a caveat – there will need to be space inside for hot water tank, often where boiler used to be, in all housing types as heat pumps need thermal storage to deliver hot water.
This is where our cuboid, modular heat batteries can make a difference. Thermino heat batteries are up to 4x smaller than the equivalent water tank, making them a modern alternative to traditional hot water cylinders and enabling heat pump installations in older properties. They are super compact, have a longer lifespan, and provide instant hot water, making them ideal for retrofitting into any property, saving space, and enhancing energy efficiency.
Myth 3: Homes with heat pumps require extra insulation
UK homes leak out heat quickly, which makes them one of the least energy efficient in Europe. Smart home company found that UK homes lost an average 3C after 5h without heating, compared to just 1C in Germany and 0.9C in Norway. The reasoning is that UK has much older homes (pre-1919) compared to Europe, which are disruptive to insulate, and the government may have to spend billions on insulation alone.
However, studies prove that heat pumps don’t need as much insulation. found that 85% of nearly 750 UK homes (from southeast Scotland to southeast England) didn’t need extra insulation for heat pump installation. The 15% that did, mostly required low-cost upgrades like loft insulation, with only a few needing more extensive work such as cavity wall insulation or door replacements. Most UK homes are suitable for heat pump installation without significant energy efficiency modifications.
However, certain home improvements are often essential for a heat pump to function optimally, including larger radiators, a compatible hot water tank, and updated pipework. The ESC study revealed that 93% of homes did replace their radiators, and 81% had a hot water tank installed as part of the heat pump system.
Given these requirements, adding a heat battery can be a space-efficient and easyfit alternative to a bulky hot water tank for the majority of UK homes. Sunamp Thermino is up to 4x smaller than a hot water tank and doesn’t need extensive pipework modifications. This compact thermal storage solution allows all homes, including space constrained properties, to benefit from heat pumps.
Myth 4: Heat pumps stop working in freezing weather
Modern air-source heat pumps are designed to operate in temperatures as low as -20C (-4F) and use far less energy that other heating systems. The greatest demonstration of the heat pump operation is in places like Norway, where the temperature regularly drops below freezing. This is why they are dubbed as the ‘most overlooked climate solution’.
In milder temperatures, modern heat pumps do have the advanced technology to achieve a COP of 3 to 4, meaning they produce 3 to 4 units of heat for every unit of electricity consumed. However, as the temperature drops to below freezing, the COP can decrease because the heat pump has to work harder to extract heat from the colder air.
Heat batteries can store a very high amount thermal energy – which can be used when the efficiency drops. By providing the supplementary heat source, heat batteries can reduce the strain on heat pumps, offering a reliable supply of hot water. Additionally, Thermino heat batteries discharge at a consistent, controlled temperature, ensuring that the hot water supply remains stable and reliable when it’s freezing outside.
Myth 5: Heat pumps will overload the grid & cause blackouts
Another very common notion is that heat pumps could cause a surge in the demand for electricity, as we swap out gas and move towards electrification of heat. Concerns are particularly strong during cold snaps – when the demand would outweigh UK’s local grid power supply, leading to blackouts.
However, National Grid ESO (NESO), responsible for balancing Britain’s electricity supply and demand, refutes claims that there is no clear strategy for reliably maintaining power in the UK’s green energy future. The national grid operator’s report models a typical winter day in 2035 – when electricity demand is expected to double due to widespread adoption of heat pumps & electric vehicles will be integrated into the electricity system.
On this day, renewable energy will make up only 40% of the UK’s generation due to low solar and wind output. The deficit, according to the forecast, will be met by gas and biomass plants with carbon capture, electricity imports, and green hydrogen. The model also forecasts a digital power grid that optimises renewable energy use, meaning electricity peaks won’t double despite overall consumption increasing.
Energy storage will play a crucial role in managing electricity demand. Thermal batteries, such as Sunamp’s Thermino, help shift the second biggest energy expense—domestic hot water, which accounts for 18% of average household daily consumption—to more cost-effective periods when demand is low. By pairing these batteries with cheaper off-peak tariffs, such as Cozy Octopus and Heat Pump Plus, homeowners can significantly reduce their energy costs.
The high energy density of Sunamp’s heat batteries, made possible by the patented Plentigrade technology, allows for the storage of vast amounts of energy in compact, cuboid units. This efficient storage solution not only optimises space but also ensures that energy is readily available when needed.
Also, Sunamp is actively involved in the ongoing EXTEND project, which aims to stabilise the grid by addressing periods of low energy production from renewable sources. This project not only helps in supporting grid as we electrify heat but also contributes to reducing carbon emissions, supporting the UK’s environmental goals. This also reflects the growing role of flexibility services highlighted in NESO’s 2025 system plan.
With higher BUS grants, simpler planning rules, supportive tariffs, and a growing installer base, there has never been a better time to make the switch to low-carbon heating.
Heat pump questions & answers 2025
1) Are heat pumps are more expensive to run than gas boilers?
Usually no. With correct sizing and time-of-use tariffs, heat pumps often match or beat gas running costs – especially when hot water is shifted off-peak.
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2) Do heat pumps work in older or less-insulated homes?
Yes. Property age isn’t a blocker; right-sizing, emitter upgrades, and basic fabric fixes make them effective. Compact energy storage solutions help where space is tight.
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3) Do homes with heat pumps require lots of extra insulation?
Not necessarily. Good insulation helps any heating system, but many homes run heat pumps well with targeted upgrades rather than major works.
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4) Do heat pumps stop working in freezing weather?
No. Modern systems are designed for sub-zero operation; output drops at very low temps, but steady low-temperature heating and good controls keep homes warm.
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5) Can heat pumps overload the grid or cause blackouts?
Unlikely. Smart controls and thermal storage shift demand away from peaks, and system planning already accounts for growing electric heating.
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