Heat Pump Cost for a 5-Bed 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 £15,496 at 14 to 16 kW, across 1,245 homes, and £15,365 at 12 to 14 kW, including the system, labour and VAT, before the grant. Above 16 kW the data thins out: the 16 to 18 kW median, £14,817 across 956 homes, sits below the 14 to 16 kW one, and only 90 homes were recorded at 18 to 20 kW, at a median of £17,878. Treat costs for the very largest single units as less certain.

A five-bedroom detached house sits well above the all-sizes median of £12,908 in April to June 2026. Our heat model puts it at around 205 square metres and 17,550 kWh of heat a year, which needs a heat pump of about 16 kW or two smaller units in cascade, with 14 to 18 radiators and a larger cylinder for two bathrooms. The range is the scheme's middle half scaled to the median for that size.

The recorded job cost already includes the heat pump, the cylinder and the labour. What moves a five-bedroom quote outside the range is the house itself: a modern executive home with underfloor heating and a cylinder already in the utility room lands near the bottom; a Victorian villa with 16 cast iron radiators, a combi boiler and an undersized electricity supply can go above the top. Ask for an itemised quote that lists each radiator to be changed and says whether that work is in the price.

The step from a 4-bed to a 5-bed is the biggest on the ladder, because it is where a single standard unit starts to run out and the electrical supply starts to matter.

At the October to December 2026 price cap, a 4-bed detached with 13,140 kWh of heat demand costs £1,164 a year on gas and £884 on a heat pump tariff; a 5-bed with 17,550 kWh costs £1,554 and £1,181. The 5-bed costs about £1,400 more to install at the median and saves £93 a year more on a heat pump tariff, so the extra takes about 15 years to earn back. On standard electricity neither house saves anything: the 4-bed pays £80 a year more than gas and the 5-bed £108 more.

Most five-bedroom detached houses need a heat pump of around 13.5 to 17.5 kW. Our model puts a typical one at 16 kW, a post-2000 house or an older one with a topped-up loft, insulated walls and new windows at 13.5 kW, and a solid-walled Victorian villa or a 1930s house with single-glazed bays at 17.5 kW, often as two units in cascade. For comparison, a quarter of the air source heat pumps fitted under the scheme in April to June 2026 were 10.8 kW or larger, so a 5-bed is at the top of the market.

The number that matters is the room-by-room heat loss calculation your MCS installer must carry out before quoting. It works out how much heat each room loses on a cold design day and sizes the unit to cover the total and your hot water. A quote with no calculation attached was sized by guesswork. An oversized unit costs more and switches on and off more often in mild weather, although the scheme's data shows the cost step between sizes is smaller than many people assume: the medians rise by about £500 to £1,400 per 2 kW band up to 14 kW, and barely at all from 14 to 16 kW.

One large unit or two? A single large unit is simpler and needs one plinth and one sound calculation, but at this size some models are three phase only and the rest draw enough current to make the network operator's approval more likely to be needed first. Two smaller units in cascade cost more and are assessed together in the sound calculation. In return they can run one unit on its own in spring and autumn, and if one fails in January the other keeps the house warm. Some installers use a cascade on the largest houses and on houses with a wing or annexe. Permitted development in England allows up to two outdoor units on a detached house.

From about 14 kW up, manufacturers' ranges split into single phase and three phase versions, and some brands stop. These are models you are likely to be quoted, with ground source at the bottom, and specifications from each manufacturer's own pages.

Ratings from the manufacturer pages in the data sources. Your heat loss calculation decides which one you need.

At this size the electrical supply narrows the field before brand does. Tell the installer whether your supply is single or three phase before they pick a model: the NIBE F2120-16 and F2120-20, for example, are three phase only, the Grant Aerona 290 range is single phase up to 15.5 kW, and the Daikin H HT comes in both. Whichever you choose, 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 covering every outdoor unit. Our heat pump noise guide explains the figures and our old house guide covers solid walls.

A heat pump runs the heating at a lower water temperature than a gas boiler, so radiators have to be larger to deliver the same warmth. A five-bedroom house typically has 14 to 18 radiators, and 6 to 9 need upsizing, usually the living room, dining room, hall and landing, and the largest bedrooms. Underfloor heating downstairs usually needs no change. Our radiator sizing guide explains how installers decide.

Hot water is where a five-bedroom house differs most from a semi. Two bathrooms, an en suite and five or six people mean a larger cylinder, and a house with a distant wing may be better served by two smaller ones than by a long run of hot pipe. The recorded job costs include the cylinder. A combi boiler means there is no cylinder at all, so you also need a cupboard, usually in a utility room; the Energy Saving Trust says a cylinder can usually fit in any cupboard at least 80cm by 80cm. An existing cylinder usually still needs replacing, because heat pump cylinders have a larger coil. Pipework matters more on a big house because the runs are long: 1970s microbore often has to be replaced with 15mm pipe on the largest radiators, and a cascade needs a low loss header to join the two units.

Zoning is the question every large-house owner asks: can the unused guest rooms be left cold? Partly. A heat pump runs best as one open system at a low, steady flow temperature, and closing off half the house makes it switch on and off. What works is one zone for the whole house, guest bedrooms set back a couple of degrees with thermostatic valves rather than off, and weather compensation running the flow temperature as low as the day allows. A genuinely separate wing or annexe justifies a second zone, which a cascade can serve from its second unit. Do not leave rooms unheated all winter: a closed-off bedroom in a solid-walled house can get cold enough to swap a heating bill for a condensation and mould problem.

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. Gas rose about 9% at this cap change. Electricity barely moved because the government removed VAT from electricity bills from 1 October 2026 to 31 March 2027, so when 5% VAT returns every heat pump figure below rises by about 5%.

The tariff makes or breaks the economics, and on a five-bedroom house the stakes are larger. On a heat pump tariff you save £373 a year against gas at today's prices, or about £314 once VAT returns to electricity; on a standard tariff you pay £108 a year more, or about £191 with VAT, so the switch only makes financial sense if you move to a heat pump tariff. Disconnecting the gas supply saves a further £108 a year in standing charge. Read our running costs guide, our tariff guide for how to get an effective rate near 18.7p, and our electric boiler vs heat pump guide if the house is heated by electricity today.

Insulation moves these numbers about as much as the tariff does. A well insulated 5-bed with 14,918 kWh costs £1,321 a year on gas and £915 on a heat pump tariff; a poorly insulated one with 19,481 kWh costs £1,725 and £1,429. The saving against gas is bigger in the well insulated house, £406 a year against £296, because a cold house pushes the demand up and drags the heat pump's efficiency down at the same time. On oil, at 11.3p per kWh, the BoilerJuice UK average of 116.20p a litre on 25 September 2026, the same typical house costs £2,333 a year, so a heat pump saves £1,152 on a heat pump tariff and £671 on standard electricity. Oil prices move, so treat the oil bill as today's figure rather than a fixed one. A five-bedroom roof also suits a large solar array; see our solar calculator and battery storage guide.

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. The grant is the same whatever the size of the house, and that is the catch. On a typical 3-bed semi the £7,500 covers 48% to 68% of the whole job; on a 5-bed it covers 38% to 54%. The scheme's size limit is 45 kW for a single heat pump and 70 kW where more than one is installed together, far above what a house needs, and a cascade of two units on one installation gets one grant, not two. Your MCS certified installer applies and deducts it from the invoice. Regulations in force from 28 April 2026 extended the scheme to 2030 and removed the need for a valid EPC, and installations carry 0% VAT until 31 March 2027. Read our BUS grant guide for the eligibility rules and our grant checker for anything else you might qualify for.

Because the grant covers a smaller share, two things matter more here: timing the insulation so the heat pump you buy is the smallest that will do the job, and checking ground source, which carries the same £7,500 grant. If anyone in the house receives a qualifying benefit, ECO4 can fund the insulation outright for work finished by 31 December 2026, and a better EPC rating comes with it. The Great British Insulation Scheme closed on 31 March 2026.

The government puts the average cost of a new gas boiler at about £3,500 including VAT, and a large house may need a bigger boiler than that average: our boiler vs heat pump comparison scales it by home size to about £4,050 for five bedrooms. Against that, a typical 5-bed heat pump job costs £2,450 to £7,950 more after the £7,500 grant, plus any radiator work not in the quote. At £373 a year saving on a heat pump tariff that is a payback of about 7 to 21 years, or 8 to 25 years once VAT returns to electricity, and it starts later than a smaller house's because the grant covers less of the bill. On a standard electricity tariff there is nothing to pay back at all, because the heat pump costs £108 a year more than gas. Against oil, the £9,000 grant and a dearer fuel shorten the payback a great deal: every £1,000 of extra cost is repaid in under a year at a £1,152 a year saving, for as long as oil stays near 11.3p per kWh. The honest case for a 5-bed on mains gas is a real saving on a heat pump tariff, a system that can outlast a boiler, and lower carbon, not a quick return. Run the numbers with our boiler vs heat pump comparison and read heat pump vs new boiler for the 15-year view.

Ground source is at least worth pricing on a 5-bed in a way it is not on a semi. 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 it needs one or two boreholes or a large area of garden. In return it usually runs more efficiently than air source, and there is no outdoor unit to site or assess for noise. 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. It comes into its own on a poorly insulated house, where groundworks are already planned, and where a large outdoor unit has nowhere to go.

For a small heat pump the electrical supply rarely comes up, which is why the 3-bed semi guide has no section on it. On a five-bedroom house it becomes a real question. A large heat pump and its backup immersion heater add a big load on top of an oven, an electric shower and perhaps a car charger, and most houses have a single phase supply.

The distribution network operator (DNO) has to be told about any heat pump, on the Energy Networks Association's form for heat pumps and electric vehicle charge points. If the home's new maximum demand, with the heat pump, is 60 amps or less and the other conditions are met, the installer can fit it and notify the DNO within 28 days, a route called Connect and Notify. If the new maximum demand is between 60 and 100 amps, the installer must apply before fitting, a route called Apply to Connect, and the DNO assesses the capacity within 10 working days, according to MCS guidance on notifying network operators. The DNO may approve it, ask for changes or require a supply upgrade, and a new three phase supply can be expensive depending on how far away the nearest suitable cable is.

This is where a cascade can earn its keep. Two single phase units can sometimes cover a house that would otherwise need one very large or three phase unit. Tell the installer what your supply is before they pick a model, and ask who is making the DNO application and what happens to the price if the DNO asks for an upgrade. On planning, permitted development in England allows up to two outdoor units on a detached house, each no larger than 1.5 cubic metres, but only one on a semi or terrace, so a cascade on an attached house needs planning permission. Our planning permission guide covers the cases where a large or listed house needs consent.

Get three quotes from MCS certified installers who have fitted 14 kW and larger systems before, 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 expected seasonal performance.
• One unit or a cascade, and why, with the model and phase of each.
• The electrical survey: main fuse rating, the load added, and whether the DNO route is Connect and Notify or Apply to Connect.
• A radiator schedule listing all 14 to 18 emitters, which ones change, and whether that work is in the price.
• The cylinder size, one or two, and where each will go.
• The zoning plan and how guest rooms will be set back.
• An MCS 020(a) sound calculation covering each outdoor unit.
• The warranty on the units and on the installation.
• Confirmation that the installer will apply for the Boiler Upgrade Scheme and deduct it from the invoice.

Installation takes longer than on a smaller house, especially when most radiators are swapped or two units are cascaded, not counting any wait for the DNO. Find installers through the MCS installer search. A large outdoor unit transmits less hum into the house on anti-vibration mounts. Larger households also use more hot water and electricity; our bills by household size guide shows what a family of five or six should expect.

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 12 kW, Mitsubishi Electric Ecodan, Daikin Altherma 3 H HT, Samsung EHS Mono HT Quiet, Grant Aerona 290, NIBE F2120 and Kensa Evo. Network operator process from MCS guidance on notifying network operators. 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).