Heat Pump Cost for a 3-Bed Detached House: Full 2026 Breakdown

The best price evidence is what installers actually charged. Every heat pump paid for through the Boiler Upgrade Scheme in England and Wales has its installed cost recorded on its MCS certificate, and the government publishes the median by heat pump size. In 2025/26 the median air source installation cost £12,686 at 8 to 10 kW and £13,943 at 10 to 12 kW, including the system, labour and VAT, before the grant. Across all sizes, the middle half of jobs in April to June 2026 cost £11,128 to £15,627.

The government does not publish costs by house type, so we size the home first. Our heat model puts a typical 3-bed detached house at 10,530 kWh of heat a year, which needs a heat pump of about 9.5 kW, and reads the scheme's median for that size. It is still a compact job: 10 to 12 radiators and a cylinder that usually fits an existing airing cupboard or utility room.

The spread inside each row comes from whether the existing radiators and pipework can be kept, how far the outdoor unit sits from the cylinder, and the installer's own pricing. Use our heat pump calculator for an estimate for your own house type, insulation and heating fuel.

Where you land depends mostly on the radiators. A 1960s or 1970s house with its original single-panel radiators may need four to six changed, which can take the job above the typical range if that work is not in the quote. A house re-radiatored in the last 15 years may need one or two and lands near the bottom. Ask for the radiator schedule, and whether it is priced in, before you accept a figure.

The 3-bed detached house sits between the 3-bed semi and the 4-bed detached on heat demand, and the costs follow. The fourth exposed wall adds roughly 630 kWh of heat demand a year against a 3-bed semi, a smaller step than the extra wall suggests, and about £300 on the median installation. The jump to a 4-bed detached house is the bigger one, around 2,600 kWh.

At the October to December 2026 price cap, the 3-bed semi with 9,900 kWh of heat demand costs £877 a year on gas, £937 on a heat pump with a standard tariff and £666 on a heat pump tariff. The 4-bed detached with 13,140 kWh costs £1,164, £1,244 and £884. The 3-bed detached figures, including oil, are in the running costs section below.

Most 3-bed detached houses need a heat pump of around 8 to 10.5 kW. Our model puts a typical one at 9.5 kW, a well insulated one at 8 kW and a poorly insulated one at 10.5 kW. For comparison, the median air source heat pump fitted under the scheme in April to June 2026 was 8 kW, and the middle half were 6 to 10.8 kW.

Heat loss scales with exposed surface, not floor area. A 3-bed semi and a 3-bed detached house can be the same size inside, but the semi shares one wall with a heated neighbour and loses little through it. The detached house loses heat through all four walls and has more external corners. In the measured data the difference is modest, which is why the two usually need heat pumps in the same size band.

The number that matters is the room-by-room heat loss calculation, not the bedroom count. A quote without one was sized by guesswork. An oversized unit costs more to buy and switches on and off more often in mild weather, and a 14 kW unit in a house that needs 9.5 kW is a mistake worth watching for in detached quotes.

The 8 to 12 kW class is where the detached market sits, and every major manufacturer has a unit in it. These are the models you are most likely to be quoted, with outputs checked against each manufacturer's own pages.

Which is best? At this size the brands are close and the design decides the result. Ask for a design flow temperature of 50°C or lower, the seasonal performance the installer expects at that temperature in writing, and an MCS 020(a) sound calculation for the outdoor unit position. The R290 units, the aroTHERM plus and the Vitocal 250-A in particular, can run hot enough to keep more of the existing radiators in a 1970s house. Our heat pump noise guide explains the noise figures.

A heat pump runs the heating at a lower water temperature than a boiler, so each radiator has to be larger to deliver the same warmth. A 3-bed detached house typically has 10 to 12 radiators, and 4 to 6 need upsizing, usually the living room, the hall and the bedrooms with two external walls. Our radiator sizing guide explains how installers decide which ones change.

You also need a hot water cylinder, and the recorded job costs above include one. If you have a combi boiler there is no cylinder today, so the installer needs somewhere to put it; the Energy Saving Trust says a cylinder can usually fit in any cupboard at least 80cm by 80cm, and most detached houses have an airing cupboard, utility room or attached garage that will take one. An existing cylinder usually still needs replacing, because heat pump cylinders have a larger coil.

The common budget breaker is microbore pipework, the 8mm or 10mm pipes fitted in many houses from the 1970s onwards. It restricts flow at heat pump temperatures and often needs replacing with 15mm or 22mm pipe. If the ground floor is an uninsulated suspended timber floor, common at this age, our underfloor insulation guide shows how to cut the heat loss through it.

These figures use the Ofgem price cap for 1 October to 31 December 2026: electricity 26.32p per kWh and gas 7.97p per kWh, with heating oil at 11.3p per kWh, the BoilerJuice UK average of 116.20p a litre on 25 September 2026. Electricity carries no VAT from 1 October 2026 to 31 March 2027, so when 5% VAT returns every heat pump figure below rises by about 5%. The worked example is 10,530 kWh of heat a year, the median for a gas heated 3-bed detached house with average insulation.

The tariff makes or breaks the economics on gas. On a heat pump tariff you save £224 a year at today's prices, or about £189 once VAT returns to electricity, and disconnecting the gas supply saves a further £108 a year in standing charge. On a standard tariff you are £65 a year worse off, or about £115 with VAT, so on gas there is no running cost case until you move to a heat pump tariff. Read our running costs guide for the full comparison and our tariff guide for how to get an effective rate near 18.7p.

Oil changes the picture. Many 3-bed detached houses in villages run on oil, and at 11.3p per kWh, the BoilerJuice UK average of 116.20p a litre on 25 September 2026, through an 85% efficient boiler, 10,530 kWh of heat costs £1,400 a year. The heat pump beats that on either tariff: by £403 a year on standard electricity and by £692 on a heat pump tariff. Oil prices move, so treat those savings as today's figures rather than fixed ones. You also lose the tank and the price swings, and a detached plot usually has room for the outdoor unit, so the switch from oil is one of the more straightforward heat pump jobs.

The Boiler Upgrade Scheme pays £7,500 towards an air source or ground source heat pump in England and Wales. Until 31 March 2027, a home heated by oil or LPG that has no mains gas connection gets an extra £1,500, making £9,000. For a typical 3-bed detached house on gas that means paying £3,500 to £8,000 for the whole job; on oil or LPG with no mains gas it is £2,000 to £6,500. Your MCS certified installer applies for the grant and it comes off the invoice. Regulations in force from 28 April 2026 extended the scheme to 2030 and removed the need for a valid EPC, installations carry 0% VAT until 31 March 2027, and you need to own the home and be replacing fossil fuel heating. Leave the old oil boiler in place until the installer has surveyed it, because the higher rate depends on what the heat pump replaces.

Read our BUS grant guide for the eligibility rules and our grant checker for anything else you might qualify for. If your household income is low and the house is in England with an EPC of D to G, the council run Warm Homes: Local Grant can pay for insulation and a heat pump. The earlier Home Upgrade Grant is closed to applications, and our Warm Homes Plan guide explains how the new scheme works.

The government puts the average cost of a new gas boiler at about £3,500 including VAT. Against that, a typical 3-bed detached heat pump job costs nothing to £4,500 more after the £7,500 grant, plus any radiator work that is not in the quote. At £224 a year saving on a heat pump tariff the payback runs from immediate to about 20 years, or up to about 24 years once VAT returns to electricity, and on a standard tariff there is no payback at all, because the heat pump costs £65 a year more to run than the boiler. On mains gas, then, a 3-bed detached house is not buying a heat pump mainly to save money. The case rests on a boiler that is due for replacement anyway, radiators that need little work, a heat pump tariff and the carbon saving.

Against oil the answer is simpler. With the £9,000 grant the whole heat pump job costs £2,000 to £6,500, and the heat pump saves £692 a year on a heat pump tariff with oil at 11.3p per kWh, so every £1,000 of extra cost over a new oil boiler pays back in about a year and a half, for as long as oil stays near that price. Claim before 31 March 2027 to get the higher grant. Run the numbers for your own house with our boiler vs heat pump comparison, and read heat pump vs new boiler for the 15-year view.

Ground source: realistic on a detached plot

Ground source is the one option a detached house unlocks. It needs a borehole or a large area of garden for a horizontal loop, and most semis cannot offer either while many detached gardens can. Under the scheme, the middle half of ground source installations in April to June 2026 cost £18,136 to £42,110, with a median of £27,232, and they get the same £7,500 grant. In return you get a system that usually runs more efficiently than air source, with no outdoor unit and no noise calculation. The government's heat pump trial measured too few ground source systems to give a reliable efficiency figure, so we do not price the running cost difference.

The upfront gap is large: roughly double the typical air source job. Ground source makes sense mainly when you are already digging, for an extension or a full landscaping job, or when the outdoor unit has nowhere acceptable to go. For most 3-bed detached houses air source is the right answer, and spare capital may be better spent finding out whether solar panels are worth it on a south-facing roof.

Placement is where a detached house wins. To be permitted development in England, the outdoor unit must pass the MCS 020(a) sound calculation, which sets a limit of 37 dB at a point one metre outside the nearest window or door of a habitable room in a neighbouring home. On a detached plot the installer has a side wall and a rear wall to choose from, the nearest neighbouring window is usually further away than on a semi, and the unit can be sited away from the bedrooms so you do not hear it either. Manufacturers rate heat pumps of this size at a sound power from the low 50s to the low 60s dB(A), and a 3-bed detached house rarely needs an acoustic enclosure. Anti-vibration feet under the unit stop hum travelling into the wall. The best spot is usually the side wall nearest the cylinder.

Planning permission is not normally needed. Since 29 May 2025, an air source heat pump on a house in England is permitted development if it passes the MCS 020(a) calculation, its outdoor unit is no larger than 1.5 cubic metres, there are no more than two on a detached house, it is not on a pitched roof or above the ground floor on a wall facing a road, and the house is not listed. In a conservation area it cannot go on a wall or roof facing a road, or nearer the road than the house. The old rule that the unit had to sit at least one metre from the boundary no longer applies. Our planning permission guide covers the exceptions and the rules in Wales and Scotland.

Get three quotes from MCS certified installers, and compare them on the design rather than the headline price. Each quote should include:

• A room-by-room heat loss calculation with the design outdoor temperature stated.
• The design flow temperature, ideally 50°C or lower, and the seasonal performance expected at it.
• A radiator schedule listing all 10 to 12 emitters, which ones change, their new sizes, and whether that work is in the price.
• The cylinder size and where it will go.
• An MCS 020(a) sound calculation for the outdoor unit position, with the nearest neighbouring window marked.
• The warranty on the unit and on the installation, and who you call when something fails.
• Confirmation that the installer will claim the Boiler Upgrade Scheme at the £7,500 or £9,000 rate and deduct it from the invoice.
• On oil, who removes the tank and what that costs, because it is often left off the quote.

Installation usually takes several days for a detached house, longer when most radiators are swapped or the oil tank comes out. Find installers through the MCS installer search. Read our old house guide if your house is pre-war with solid walls.

Installed costs from the DESNZ Boiler Upgrade Scheme statistics, August 2026, Table A1.3A (median cost by heat pump size, 2025/26, 30,590 air source installations) and Table Q1.1A (April to June 2026 quartiles). Costs are self-reported by MCS installers and include the system, labour and VAT, before the grant. Heat pump efficiency from the Electrification of Heat trial report (Energy Systems Catapult for DESNZ, December 2024, Table 1.2). Heat demand from our heat model, built on the DESNZ National Energy Efficiency Data-Framework (NEED) 2026. Measured insulation savings from NEED impact of measures 2026. Energy prices from the Ofgem price cap for October to December 2026. Heat pump tariff: Cosy Octopus at October 2026 rates with 60% of heating in the cheap hours and 10% in the 4pm to 7pm peak, as costed in our tariff guide. New gas boiler cost from the DESNZ Boiler Upgrade Scheme 2026 to 2030 summary business case, footnote 8, scaled by home size as in our boiler vs heat pump comparison. Grant rules from GOV.UK and The Boiler Upgrade Scheme (England and Wales) (Amendment) Regulations 2026. VAT from HMRC VAT Notice 708/6. Planning rules from the permitted development rules, Class G and MCS 020(a). Insulation costs from the Energy Saving Trust. Full method on our methodology and data sources pages. Heat pump specifications from the manufacturers: Vaillant aroTHERM plus, Mitsubishi Electric Ecodan outdoor units, Daikin Altherma 3 R, Samsung EHS Mono, Octopus Cosy, Grant Aerona 290 and Viessmann Vitocal 250-A. Heating oil price from BoilerJuice: the UK average of 116.20p a litre including VAT on 25 September 2026, converted at 10.294 kWh a litre using the DESNZ greenhouse gas conversion factors 2026 (gross calorific value).