High-temperature heat pumps can help reduce disruption and installation costs for homes and properties where a standard heat pump would require extensive and expensive modifications to the heat distribution system.

Heat pumps have become the desirable and natural choice for households replacing an existing heating system. The Warm Homes Plan targets over 450,000 heat pump installations per year by 2030, and high-temperature heat pumps are a practical alternative for many households where low-temperature models fall short.

High-temperature heat pumps are suitable for existing properties because they integrate with existing high-temperature distribution systems, including standard radiators, and can meet domestic hot water demand. That compatibility is what makes them the right solution for much of the UK’s older housing stock, where standard heat pumps would require costly preparatory work before installation could begin.

Choosing one isn’t straightforward, however. They cost more than standard heat pumps, run at lower seasonal efficiency when pushed to high temperatures, and aren’t the right choice for every property. Understanding which homes genuinely benefit, which models lead the market in 2026, and what the full cost looks like can help you make an informed decision.

Best High-Temperature Heat Pumps at a Glance:

1. Best Overall — Vaillant aroTHERM Plus
2. Best for Cold Climates — Daikin Altherma 3 H HT
3. Best for Reliability — Mitsubishi Ecodan
4. Best Value After Grant — Octopus Cosy Heat Pump
5. Best for Maximum Temperature — LG THERMA V R32
6. Best for Domestic Hot Water — Hitachi Yutaki S Combi

The Best High-Temperature Heat Pumps in the UK 2026

Best Overall — Vaillant aroTHERM Plus

• Max flow temperature: 75°C
• Refrigerant: R290 (propane, GWP = 3)
• SCOP at 35°C: Up to 5.03
• Sizes available: 3.5kW, 5kW, 7kW, 10kW, 12kW
• Installed cost (before BUS grant): £9,000 to £15,000
• Warranty: 5 years (extendable with annual service)

Best for: Older properties with standard radiators, homeowners prioritising long-term efficiency and environmental credentials, and properties replacing oil or LPG boilers.

The aroTHERM Plus uses R290 refrigerant to achieve higher flow temperatures of up to 75°C, making it suitable for use with existing radiators. It operates down to -25°C and achieves a Seasonal Coefficient of Performance (SCOP) of up to 5.03. R290 has a global warming potential of just 3, compared to R32 at 675, making it the most environmentally responsible refrigerant in the mainstream UK heat pump market. That matters both for long-term regulatory compliance and for homeowners who want the most future-proof installation available.

The aroTHERM Plus is Quiet Mark certified on four of its five models, and is one of the quietest air source heat pumps available. It’s also the first mainstream ASHP to use the natural refrigerant R290. The 75°C flow temperature capability means it works with the vast majority of existing standard radiator systems in older UK homes without requiring costly replacements.

It requires a Vaillant-approved installer, which limits your choice of engineer. You must also pair with a hot water cylinder since there’s no integrated cylinder option, and it sits at the premium end of the installed cost range. For a homeowner who plans to stay in their property long-term, the combination of industry-leading efficiency, the greenest available refrigerant, and compatibility with existing radiators makes it the strongest all-round choice.

Best for Cold Climates — Daikin Altherma 3 H HT

• Max flow temperature: 70°C
• Refrigerant: R32 (GWP = 675)
• SCOP at 35°C: Up to 5.43 (the highest peak figure of any brand in this comparison).
• Sizes available: Up to 18kW
• Installed cost (before BUS grant): £7,000 to £14,000
• Warranty: 12 years when installed by a Daikin-certified engineer

Best for: Scottish and northern properties, exposed rural locations, older homes where cold-weather reliability is the priority, and anyone replacing an oil boiler off the gas grid.

The Daikin Altherma 3 H HT can supply water at temperatures up to 70°C (the same as gas boilers), even when it’s -15°C outside. It achieves a peak COP of 5.43, the highest among any brand in this comparison.

Its cold-weather performance is its decisive advantage for Scottish properties, exposed northern locations, and anyone who wants the reassurance of full heating capacity through the depths of a British winter. While many heat pumps struggle to heat old-fashioned radiators, the Altherma 3 H HT uses Bluevolution technology to deliver water temperatures up to 70°C without an immersion heater, making it a viable drop-in replacement for gas boilers in older UK housing stock.

The 12-year warranty when installed by a Daikin-certified engineer is the longest available in the high-temperature heat pump category and represents a meaningful commitment to long-term reliability. The Daikin Onecta app also provides intuitive smart control and integrates with Alexa and Google Assistant.

Best for Reliability — Mitsubishi Ecodan R290

• Max flow temperature: 75°C
• Refrigerant: R290 (GWP = 3)
• SCOP at 35°C: Up to 4.9
• Sizes available: 5kW to 17kW
• Installed cost (before BUS grant): £10,000 to £15,000
• Warranty: 3 years standard, extendable to 7 years with registered MCS installation

Best for: Most homes where long-term support and parts availability are priorities, anyone who wants the widest choice of MCS-certified installers, properties needing both 75°C flow temperature and natural refrigerant.

Mitsubishi’s Ecodan R290 pushes the boundaries with water as hot as 75°C, even when it’s below freezing outside. The Ecodan has the largest installed base of any heat pump in the UK, with over 15 years of UK installations, resulting in the widest installer and service network available. If something goes wrong, finding a trained engineer is faster and easier with an Ecodan than with any competing brand.

The Ecodan ecosystem includes pre-matched cylinders and a strong installer training network. Mitsubishi’s Zubadan technology maintains near-full output at -15°C and operates down to -28°C, matching Daikin’s cold-weather performance while also using the R290 refrigerant instead of the R32 used by the Daikin HT range.

For homeowners who want the combination of maximum flow temperature, natural refrigerant, and the deepest installer support network in the UK, the Ecodan R290 is the rational choice.

Best Value After Grant — Octopus Cosy Heat Pump

• Max flow temperature: 65°C (Turbo configuration)
• Refrigerant: R290 (GWP = 3)
• SCOP at 35°C: Up to 4.1 (real-world fleet average)
• Sizes available: 6kW, 9kW, 12kW
• Installed cost after BUS grant: Median ~£4,459

Best for: Budget-conscious buyers, existing Octopus Energy customers, and properties with average to good insulation where 65°C flow is sufficient.

The Cosy 6, Cosy 9, and Cosy 12 are R290 units capable of 65°C flow in Turbo configuration. It can reach a real-world SCOP of 3.6 across the installed base, with leading installs reaching 4.0-4.1. The Cosy is the cheapest mainstream option once the BUS grant is applied, with possible median post-grant prices of £4,459.

The 65°C maximum flow temperature is lower than the Vaillant, Mitsubishi, or LG options. It can be sufficient for most existing radiator systems in average to well-insulated homes, but may fall short in the most demanding older properties with single-panel radiators throughout.

The Cosy’s deep integration with Octopus smart tariffs, particularly Octopus Cosy and Intelligent Octopus, can reduce effective electricity costs to well below the standard unit rate and improve running cost economics. The Cosy represents exceptional value if you’re an Octopus Energy customer, or are willing to switch. The R290 refrigerant also means it’s future-proof despite the accessible price point.

Best for Maximum Temperature — LG THERMA V R32

• Max flow temperature: 80°C
• Refrigerant: R32 (GWP = 675)
• SCOP at 35°C: Up to 4.6
• Sizes available: 5kW to 16kW
• Installed cost (before BUS grant): £8,000 to £14,000
• Warranty: 5 years parts and labour

Best for: Properties with the most demanding existing radiator systems, homes with large cast iron radiators, and any installation where 75°C flow temperature is insufficient.

The LG THERMA V R32 achieves a SCOP of 4.6. It reaches 80°C, one of the highest maximum flow temperatures available in the domestic UK market, matched only by the Hitachi Yutaki S Combi.

The LG THERMA’s 80°C capability removes any compatibility concern for properties with the most demanding existing radiator systems, and where single-panel cast iron radiators or large Victorian cast iron column radiators require genuinely high flow temperatures to deliver adequate heat output.

The LG offers a comparable proposition at the premium temperature end of the market. The R32 refrigerant is a limitation relative to the Vaillant and Mitsubishi R290 models on environmental grounds, but the 80°C ceiling provides a margin that no R290 competitor currently matches in the residential market.

Best for Domestic Hot Water — Hitachi Yutaki S Combi

• Max flow temperature: 80°C
• Refrigerant: R134a (cascade circuit)
• SCOP at 35°C: Up to 4.0
• Sizes available: 4kW to 16kW
• Installed cost (before BUS grant): £10,000 to £18,000

Best for: Large properties with high domestic hot water demand, homes with rain showers or multiple bathrooms, properties where Legionella control requires sustained 80°C hot water storage.

The Hitachi Yutaki S Combi’s defining capability is its patented Cascade R134a Heat Pump Circuit, which delivers domestic hot water at up to 80°C. It’s the highest available in the UK domestic market and sufficient for the most demanding hot water applications, including rain showers and large family homes.

It’s also suitable for properties where Legionella risk management requires consistently high stored water temperatures rather than periodic immersion-heater cycles. Its 80°C space-heating flow temperature matches the LG THERMA V, but it also adds a unique Cascade circuit for hot water production. This makes it the most capable overall system for properties that require high temperatures for both space heating and domestic hot water.

The trade-off is the highest installed cost among the options and the lowest SCOP at low temperatures. The Cascade circuit’s efficiency advantage is most pronounced at high output temperatures, where competing single-circuit designs lose efficiency more rapidly.

What Are High-Temperature Heat Pumps?

Government guidance defines domestic high-temperature heat pumps as air and ground-source heat pumps with a capacity of less than 45kW that are capable of producing output temperatures of 65°C. These are comparable to gas and oil-boiler flow temperatures, making high-temperature models suitable for homes with existing radiators that aren’t sized for lower-temperature heating.

That single capability is what distinguishes high-temperature heat pumps from the standard heat pumps that dominate new-build installations and account for the majority of the UK’s growing heat pump market.

All heat pumps work by extracting heat from the outside air or the ground and concentrating it, using a refrigerant cycle, to produce useful heat for a building. The difference in a high-temperature model isn’t the fundamental mechanism, but the engineering design that allows the refrigerant cycle to reach and maintain higher output temperatures without the efficiency collapse that affects standard heat pump designs at elevated temperatures.

How Do High-Temperature Heat Pumps Work?

Standard heat pump designs lose efficiency rapidly above 55°C. The thermodynamic gap between the heat source (outside air) and the heat output becomes too large for the standard single-stage refrigerant cycle to bridge economically. High-temperature heat pumps overcome this through one of three engineering approaches:

Enhanced Vapour Injection (EVI)

EVI adds an injection loop to the standard refrigerant circuit. The additional injection loop allows a portion of condensed refrigerant to be diverted through a separate heat exchanger and injected back into the compressor as superheated vapour. This adds a second stage to the compression process, boosting the output temperature without the proportional efficiency loss of simply running harder on a standard circuit.

Cascade Systems

In a cascade system, two entirely separate refrigerant circuits operate in series. The first circuit lifts heat to an intermediate temperature, and the second circuit lifts that intermediate heat to the final high-output temperature. Each circuit uses a refrigerant optimised for its specific temperature range. This is how the Hitachi Yutaki S Combi delivers 80°C domestic hot water via an R134a cascade circuit in parallel with the main heat pump cycle.

Optimised Refrigerants

The choice of refrigerant in a high-temperature heat pump affects its environmental credentials, thermodynamic performance, and its future regulatory compliance. Three refrigerants dominate the current UK market:

• R290 (propane) has a global warming potential (GWP) of just 3, which is essentially negligible compared to synthetic refrigerants, and its thermodynamic properties naturally support higher output temperatures. It’s flammable, which requires specific installation precautions and smaller charge quantities, but it’s the most environmentally responsible option available and the direction the UK market is moving. The Vaillant aroTHERM Plus and Mitsubishi Ecodan R290 both use it.
• R32 has a GWP of 675, which is considerably higher than that of R290. It’s less flammable and simpler to handle, which is why it remains widely used. It may face tightening F-gas regulations in the coming years, which is worth factoring in for a system you expect to use for 20 or more years.
• R134a is used specifically in cascade high-temperature circuits, as in the Hitachi Yutaki S Combi. Its thermodynamic properties make it effective at the elevated temperatures at which the second cascade circuit operates. Its GWP of 1,430 is the highest of the three, a limitation of the cascade approach’s engineering requirements.

High-Temperature vs Standard Heat Pumps: What’s the Difference?

Standard heat pumps are designed to operate at flow temperatures of 35°C to 55°C. At those temperatures, they achieve their highest seasonal efficiency, with SCOP figures of 3.0 to 4.5 in real-world UK conditions. A heating system designed to work at those temperatures needs radiators significantly larger than those installed in most pre-1990 UK properties, or underfloor heating, to distribute heat effectively.

High-temperature heat pumps can be integrated into an existing heating system with minimal disruption to the heat distribution side. The radiators, pipework, and controls were already designed for those temperatures.

How They Compare:

Which Properties Benefit Most from a High-Temperature Heat Pump?

A high-temperature heat pump is the stronger choice when the cost of adapting the property for a standard model would approach or exceed the cost premium of the high-temperature unit itself. The following property types fall most clearly into this category:

• Pre-1990 properties with original radiators. Single-panel and small double-panel radiators sized for 70°C to 80°C flow temperatures will not deliver adequate heat output at the 35°C to 45°C flow temperatures produced by a standard heat pump. Replacing every radiator in a typical three-bedroom semi costs £2,000 to £4,000. If a high-temperature heat pump costs £1,500-£2,500 more than a standard equivalent, it’s worth considering.
• Properties heated by oil or LPG boilers. Off-gas-grid properties represent the clearest use case. Oil and LPG boilers run at high flow temperatures, and the existing radiators are sized accordingly. Replacing an off-grid heating system with a high-temperature heat pump requires no changes to the heat distribution side. The running cost savings compared with oil or LPG are also more compelling than the gas comparison. Oil and LPG unit costs are typically two to three times the price of gas per kWh of heat.
• Listed buildings and conservation area properties. Where planning restrictions prevent the insulation upgrades, a high-temperature model is more suitable. It can work within the existing fabric constraints rather than requiring fabric changes that aren’t permitted.
• Properties with solid walls. External wall insulation can disrupt a building’s appearance and may require planning consent in many areas. Internal wall insulation reduces room sizes. Where neither option is practical, a high-temperature heat pump is the better choice.

Properties Better Served by a Standard Heat Pump

A standard low-temperature heat pump will typically deliver better real-world efficiency and lower running costs in the following situations:

• Well-insulated modern homes. Properties built to post-2000 Building Regulations standards typically have cavity wall and loft insulation as standard. Their radiators are often sized more generously than older equivalents. A standard heat pump operating at 45°C in a well-insulated home will achieve a higher SCOP than a high-temperature model operating at 65°C or above.
• Properties already fitted with underfloor heating. Underfloor heating operates most efficiently at a flow temperature of 30°C to 40°C. A high-temperature model in a property with UFH will never use its high-temperature capability and will operate less efficiently than a correctly specified standard unit.
• New builds and recently renovated properties. Modern construction standards mean these properties almost always suit standard heat pumps. High-temperature specifications in new builds are a sign of incorrect system design rather than a property requirement.

How Efficient Are High-Temperature Heat Pumps?

Efficiency is the practical measure that determines what you pay to run your heating system every year.

Real-World SCOP in UK Conditions

The SCOP figures quoted by manufacturers are calculated at a standardised European climate reference point. UK conditions, particularly the mild, damp winters, are generally more favourable than those of the test climate. This means real-world performance often meets or slightly exceeds the published SCOP when the system is correctly installed and commissioned.

Real-world SCOPs of 2.8 to 3.5 are typical for systems operating at flow temperatures of 55 °C to 65 °C. Systems operating at 70°C or above consistently show SCOPs in the 2.0-2.8 range. This is a reflection of the temperature-efficiency trade-off.

These figures compare with real-world SCOPs of 3.0 to 4.0 for standard heat pumps in well-suited UK properties. The efficiency gap between high- and standard-temperature models is real but varies significantly depending on how the system is commissioned and controlled.

The Flow Temperature Effect in Practice

The most important variable in a high-temperature heat pump’s real-world efficiency is the flow temperature it actually operates at day to day. A heat pump can achieve a higher annual SCOP by running at 55°C for 8 months of the year and at 70°C only on the coldest days, rather than running at 70°C continuously.

Weather compensation controls manage this automatically. By reducing the flow temperature as outdoor temperatures rise, they keep the heat pump operating as close to its efficiency peak as heating demand allows. A 10kW Vaillant aroTHERM Plus, correctly configured with weather compensation, will outperform a 10kW unit of any brand running at a fixed, high flow temperature throughout the season.

A well-commissioned HTHP with accurate weather compensation curves, correct system pressures, and a properly balanced distribution circuit will consistently outperform a poorly commissioned premium model. When evaluating installers, ask specifically how they set weather compensation curves and what SCOP data they have from previous comparable installations.

Pros and Cons of High-Temperature Heat Pumps

Advantages

• Compatible with existing standard radiators. A high-temperature heat pump is integrated into an existing heating system at the same flow temperature as the boiler it replaces. This eliminates the radiator replacement cost required for a standard heat pump installation.
• No insulation upgrade required. Standard heat pumps operate most efficiently in well-insulated homes. For homeowners who are unable or unwilling to fund major insulation work, this removes a significant barrier to low-carbon heating.
• Lower carbon than oil or LPG. For off-gas-grid properties currently heated by oil or LPG, a high-temperature heat pump delivers a meaningful carbon reduction. Even a relatively inefficient heat pump produces significantly fewer CO2 emissions per kWh of useful heat than oil or LPG combustion.
• Eligible for the £7,500 BUS grant. The Boiler Upgrade Scheme applies equally to high-temperature and standard heat pumps, reducing the effective installed cost by £7,500 for any eligible homeowner in England or Wales.
• Future-proof. A high-temperature heat pump installed now runs on electricity, positions the property for an increasingly decarbonised grid, and you won’t need to replace it in response to future fuel-switching policy.
• Significant running cost savings vs oil and LPG. At current oil and LPG prices, replacing a fossil-fuel boiler with a high-temperature heat pump rated at 3.0 SCOP typically reduces annual heating bills by 40-60%. The economics are considerably more compelling than the gas comparison for the large proportion of HTHP buyers who are replacing oil.

Limitations

• Higher upfront cost than standard heat pumps. High-temperature models cost approximately 25% more than standard equivalents. For buyers comparing two heat pump types rather than a heat pump against a boiler, that premium requires justification from the property’s specific characteristics.
• Lower seasonal efficiency than standard heat pumps in suitable properties. A standard heat pump operating at 45°C in a well-insulated home consistently achieves a higher SCOP than a high-temperature model operating at 65°C-75°C in the same property. The HTHP’s advantage is compatibility with properties where a standard model would underperform, not superiority in efficiency in properties where both would work.
• Currently, it’s more expensive to run than gas. At the current electricity-to-gas price ratio and an SCOP of 3.0, a high-temperature heat pump costs approximately 20-30% more per year to run than the most efficient gas boilers operating at above 90% efficiency. That gap narrows significantly on a smart heat pump tariff but doesn’t disappear entirely at current UK price ratios.
• Requires a hot water cylinder. No heat pump, high-temperature or standard, provides instantaneous hot water on demand. A hot water cylinder is required for stored hot water. For properties currently served by a combi boiler, this means a cylinder needs to be accommodated, typically in an airing cupboard or purpose-built space.
• Not suitable for every older property. Older homes with very small room sizes, insufficient space for a hot water cylinder, planning restrictions that prevent outdoor unit installation, or heat demands that exceed the available air source heat pump sizes may not be suitable, regardless of property age or insulation level.

Pros and Cons at a Glance:

High-Temperature Heat Pump Running Costs in 2026

High-temperature heat pumps currently cost more to run than gas boilers on a standard tariff, but significantly less than oil and LPG. The economics shift materially depending on the smart tariff you’re on and the SCOP your installation achieves.

The Current Electricity-to-Gas Price Gap

At the current Ofgem price cap rates of 24.67p/kWh for electricity and 5.74p/kWh for gas (April to June 2026), gas delivers heat more cheaply per kWh than electricity, even after accounting for the heat pump’s efficiency advantage.

A gas boiler at 90% efficiency delivers heat at approximately 6.4p per kWh. A high-temperature heat pump with a SCOP of 3.0 delivers heat at approximately 8.2p per kWh. That gap makes the running cost case against gas challenging at current prices.

For oil and LPG, the calculation inverts. Domestic heating oil currently costs approximately 7.5p to 9.0p per kWh and LPG approximately 8.0p to 10.5p per kWh. This is already above or approaching the cost per kWh of useful heat from a high-temperature heat pump, even at a conservative SCOP. For properties currently heated by oil or LPG, a high-temperature heat pump already delivers a running cost saving on day one.

Worked Annual Cost Comparison:

The table below compares annual heating costs for a typical three-bedroom semi-detached home with 12,000 kWh annual heat demand at current energy prices:

The table reveals three important conclusions:

• A high-temperature heat pump at a SCOP of 3.5 on a standard tariff broadly matches gas running costs. This is achievable with a well-commissioned installation and weather compensation controls.
• A smart tariff at 15p/kWh transforms the economics, producing running costs 22% below gas.
• Any high-temperature heat pump offers meaningful savings when replacing oil or LPG, regardless of SCOP.

Smart Tariffs for Heat Pump Users

Several major suppliers offer tariffs specifically structured around heat pump usage patterns:

• Octopus Cosy provides six hours of cheap-rate electricity per day, two hours in the morning and four hours in the afternoon, at reduced rates. Running the heat pump during these windows and using thermal mass to carry heat through expensive peak periods significantly reduces effective electricity costs below the standard cap rate.
• Economy 7 and Economy 10 provide off-peak overnight electricity at reduced rates. Heat pump users with good thermal mass or a well-insulated home can preheat overnight, reducing the heat pump’s output during expensive daytime hours.
• Intelligent Octopus and Agile tariffs offer dynamic pricing that rewards flexible demand. High-temperature heat pumps with smart controls capable of responding to price signals can achieve average effective rates of 10 to 15p/kWh when operated intelligently across a full year.

The running cost differential between a standard tariff and a well-optimised smart tariff is typically £300 to £600 per year for a high-temperature heat pump serving a three-bedroom home. Over a 15-year system life, that amounts to £4,500 to £9,000, a figure that significantly alters the total cost of ownership calculation when compared against a gas boiler.

High-Temperature Heat Pump Installation Costs in 2026

According to the Energy Saving Trust, the typical cost of installing an air source heat pump is around £11,000. High-temperature models carry a 10-20% cost premium over that figure. For a property where a standard heat pump would cost £11,000 installed, a high-temperature equivalent typically costs £12,000 to £13,200, a difference of £1,000 to £2,200.

Full System Cost Breakdown

The heat pump installation price covers more than the unit itself. A properly specified installation includes:

What Affects Your Final Price?

Several variables move the total cost up or down from the ranges above:

• Property size and heat demand. A larger home needs a higher-capacity unit. A 5kW unit suits a small, well-insulated property, while a 12kW to 16kW unit is needed for a large period property with significant heat loss. Unit cost scales with output capacity, so a 16kW HTHP costs substantially more than a 7kW equivalent.
• Existing system condition. Properties with pipework in poor condition or no existing hot water cylinder incur additional costs. Even though a high-temperature heat pump reduces the need for radiator upgrades compared to a standard heat pump, some properties still require partial upgrades to their distribution system.
• Region. Labour costs vary across the UK. Installation in London and the South East typically runs 15 to 25% higher than the national average. Scotland and Northern England tend to be slightly below average.
• Ancillary works. Electrical upgrades to accommodate the heat pump’s power supply, new outdoor unit bases, screening or planning consent in conservation areas, and structural works for cylinder installation all add to the total. Always ask your installer to itemise any ancillary works in writing before committing.

Grants and Funding for High-Temperature Heat Pumps in 2026

The Boiler Upgrade Scheme (BUS) — Updated April 2026

The Boiler Upgrade Scheme remains the primary grant for heat pump installations in England and Wales. Grant values for air-to-water heat pumps, the category all high-temperature heat pumps fall into, remain at £7,500.

The scheme was extended to 2030, with a £295 million budget confirmed for 2025/26, the largest annual BUS allocation to date. The EPC requirement has also been removed, and you no longer need a valid EPC to qualify for the BUS grant.

Your MCS-certified installer handles the entire grant application on your behalf. The £7,500 is deducted from your installation invoice, so you never handle the grant money. BUS has no income requirements or means testing and is open to any homeowner in England or Wales looking to replace their fossil-fuel heating system.

The £9,000 Uplift for Off-Gas-Grid Properties

The existing £7,500 BUS grant will be topped up by an additional £1,500 for eligible off-gas-grid properties, taking the total grant value to £9,000. The uplift is expected to open for applications in July 2026 and applies to air-to-water and ground-source heat pump installations in England and Wales.

The government aims to help households most impacted by rising energy prices, particularly in rural areas, to electrify their heating and provide greater certainty over energy bills. For the millions of households currently heated by oil or LPG, the core market for high-temperature heat pumps, this means a net installed cost of approximately £2,000 to £6,000 after the £9,000 grant.

The Warm Homes Plan

The Boiler Upgrade Scheme has been expanded under the Warm Homes Plan, with £2.7 billion in funding available up to 2030. For lower-income households, the Warm Homes: Local Grant scheme, delivered through local councils, may fund a heat pump installation at no upfront cost for properties with an EPC rating of D to G. This is income-tested and separate from the BUS.

Full eligibility criteria and application routes may vary, so contact your local council directly to find out whether applications are open in your area.

Home Energy Scotland Grant and Loan

Scottish homeowners can access a grant, an interest-free loan or a combination of both to install heat pumps through the Home Energy Scotland Grant and Loan scheme. A grant of up to £7,500 is available, with an additional £7,500 as an optional interest-free loan. An uplift of £1,500 is also available for rural and island homes.

ECO4 — For Qualifying Benefit Recipients

Households receiving qualifying benefits with an EPC of D to G may qualify for a fully funded heat pump through ECO4, which runs until 31 December 2026. Find an MCS-certified installer registered on the ECO4 scheme, or contact your local council to be referred through the LA Flex route. ECO4 and BUS cannot be combined for the same installation. If you’re eligible for ECO4, you should establish whether the fully funded ECO4 route or the BUS discount route is better, depending on your specific installation cost.

How to Get a High-Temperature Heat Pump Installed

Step 1 — Commission a Heat Loss Survey

Every MCS-certified heat pump installation in the UK is legally required to have a heat loss survey under the Microgeneration Installation Standard (MIS) 3005 before any work begins. The survey calculates your home’s room-by-room heat demand under design conditions, assesses your existing radiators’ heat output at different flow temperatures, and determines the correct unit size for your property.

A survey also confirms whether a high-temperature or standard heat pump is the correct specification for your property. If an installer quotes a unit without first conducting a heat loss survey, treat this as a disqualifying signal. It means the specification is based on guesswork rather than calculation.

Step 2 — Find an MCS-Certified Installer

All heat pump installers must hold MCS certification to carry out BUS-funded installations. MCS certification requires installers to meet specific standards for heat pump design, installation quality, and commissioning.

Get a minimum of two written quotes. Each quote should specify the proposed unit make and model, the output capacity in kW, the calculated heat loss figure from the survey, the installed price before and after the BUS grant, and an itemised list of any ancillary works included. A quote that lacks these details is incomplete regardless of the headline price.

Step 3 — Evaluate Quotes Carefully

When comparing quotes, ask each installer:

• What SCOP do you expect this installation to achieve, and what comparable installations can you reference?
• How will you set weather compensation curves for this property?
• What commissioning checks will you carry out before handover?
• Do you have experience with high-temperature heat pumps, and can you provide references for comparable installations?

An installer who cannot answer these questions confidently has probably not installed many heat pumps, or not installed many high-temperature models specifically. The skill set for a standard heat pump and a high-temperature installation overlaps significantly but isn’t identical.

Step 4 — Apply for the BUS Grant

Your MCS-certified installer handles the BUS grant application on your behalf. The grant is deducted directly from your installation invoice. You don’t handle the grant money, and there is no separate application process for the homeowner.

The installer submits the application; Ofgem issues a voucher; the installer redeems the voucher upon completion; and the £7,500 is paid directly to the installer. Confirm with your chosen installer that they have submitted BUS applications before and are familiar with the current process. A first-time BUS application can cause delays if the installer is unfamiliar with the portal.

If you qualify for the Warm Homes: Local Grant or ECO4 route, contact your local council before appointing an installer.

Step 5 — Installation and Commissioning

A standard high-temperature air source heat pump installation typically takes two to three days. The process involves outdoor unit installation, indoor hydronic connections to the existing heating circuit, hot water cylinder installation if required, electrical connection by a suitably qualified electrician, controls configuration, and system commissioning.

Commissioning is the critical final step. It involves setting flow temperatures, configuring weather-compensation curves for your specific property and climate zone, balancing the system across all radiators, and verifying that the heat pump operates within its design parameters. Poor commissioning can cause a heat pump to perform below its rated SCOP in real-world use.

At handover, your installer should provide the MCS certificate, the heat loss survey documentation, a commissioning report detailing the set operating parameters, warranty registration confirmation, and a walkthrough of the controls. Don’t accept a handover without this documentation.

Step 6 — Annual Servicing

An annual service by a qualified heat pump engineer maintains the system’s efficiency, satisfies most manufacturer warranty conditions, and identifies any components approaching failure before they cause a breakdown in winter.

Final Thoughts on the Best High-Temperature Heat Pumps

High-temperature heat pumps are the most practical path to low-carbon heating for UK homes that don’t meet the conditions required by a standard heat pump. The running cost savings against oil and LPG boilers are immediate, and they grow as electricity prices continue to track below oil and LPG on a cost-per-unit-of-heat basis.

Compared to gas boilers at 90% efficiency, a high-temperature heat pump on a standard tariff costs more per year to run. However, the gap narrows significantly when you’re on a smart heat pump tariff. It closes further as the electricity grid decarbonises, and reverses entirely if carbon pricing on gas tightens as expected over the coming decade.

A well-commissioned high-temperature heat pump with correctly configured weather compensation, an accurately sized unit, and a balanced distribution circuit will significantly outperform a poorly installed premium model. Choose your installer as carefully as you choose your unit and ask specifically about their experience with high-temperature models, not just heat pumps in general.

FAQs About High-Temperature Heat Pumps

What Is a High-Temperature Heat Pump?

A high-temperature heat pump produces flow temperatures of 65°C to 80°C, comparable to a gas or oil boiler. High-temperature models are specifically designed for older UK properties where upgrading the heat distribution system would be disruptive or prohibitively expensive. They use Enhanced Vapour Injection, cascade circuits, or optimised refrigerants such as R290 to efficiently achieve those elevated temperatures.

Are High-Temperature Heat Pumps Suitable for Older Homes?

Yes. They’re specifically recommended for pre-1990 properties with original standard-sized radiators, solid walls, and significant heat loss where a standard heat pump would require costly preparatory work. A heat loss survey will confirm whether your property is a strong candidate and establish the correct unit size. Properties off the gas grid and heated by oil or LPG are the clearest use case since the high-temperature heat pump replaces the boiler directly without any changes to the existing radiator system.

How Much Does a High-Temperature Heat Pump Cost to Install?

The typical cost of installing an air source heat pump is around £11,000. High-temperature models carry a 10-20% cost premium over that figure. For a property where a standard heat pump would cost £11,000 installed, a high-temperature equivalent typically costs £12,000-£13,200.

How Efficient Are High-Temperature Heat Pumps?

High-temperature heat pumps achieve a real-world SCOP of 2.5 to 3.5 in typical UK conditions, meaning they deliver 2.5 to 3.5 units of heat per unit of electricity consumed. This is lower than that of standard heat pumps in well-suited properties (SCOP 2.8 to 4.0) because efficiency falls as the output temperature rises. Weather compensation controls, which reduce flow temperature on milder days, are essential for maximising seasonal efficiency.

Do High-Temperature Heat Pumps Qualify for the BUS Grant?

Yes. All air-to-water heat pumps, the category covering every high-temperature model, qualify for the £7,500 Boiler Upgrade Scheme grant in England and Wales. From July 2026, off-gas-grid properties replacing oil or LPG boilers qualify for £9,000. Your MCS-certified installer applies the grant on your behalf and deducts it directly from your invoice. The BUS has been extended to 2030 and is accessible to more properties than at any point since the scheme launched.

What Is the Difference Between a High-Temperature and a Standard Heat Pump?

The core distinction is maximum flow temperature, with 65°C to 80°C for high-temperature models versus 45°C to 55°C for standard ones. Standard heat pumps achieve higher seasonal efficiency but require larger radiators or underfloor heating to work effectively. High-temperature models work with existing standard radiators in older properties but are more expensive and operate at a lower SCOP. The right choice depends entirely on your property’s existing heat distribution system and insulation level.

Sources and References

• Department for Energy Security & Net Zero – Warm Homes Plan
• GOV.UK – Evidence gathering – Low Carbon Heating Technologies – Domestic High Temperature Heat Pumps
• Ofgem – Energy price cap unit rates and standing charges
• Energy Saving Trust – Air Source Heat Pumps
• GOV.UK – Boiler Upgrade Scheme 2026 – 2030 Summary Business Case
• Home Energy Scotland – Home Energy Scotland Grant and Loan
• MCS – The Heat Pump Standard