Air source heat pump cost: the real numbers

Air source heat pump cost in the UK sits at a median of £13,041, covering the unit, installer fees and any home upgrades needed, according to the latest official Boiler Upgrade Scheme figures. That number is barely moving. It is also 11% lower in real terms than when the scheme launched in 2022, which cuts against the usual line that heat pumps keep getting pricier. Take the £7,500 grant off that median and most households are left with a balance in the mid four figures, comfortably inside the Warm Homes Loan's £20,000 air source cap.

Most cost guides stop at a rounded range and a shrug. This one starts from the actual redemption data behind the grant scheme, then works out why your own quote will land somewhere else on that curve.

What the official numbers actually say

Every Boiler Upgrade Scheme voucher gets logged when it is redeemed, and the resulting dataset is about as close to ground truth as UK heat pump pricing gets. Analysis of that data by Nesta shows the median air source installation cost rose only slightly this year, from £12,973 to £13,041, a rise of under half a percent. Zoom out to the full four years and the trend is downward, not up: costs have fallen 11% since the scheme opened in 2022.

That is not what most search results imply. A lot of installer marketing and older blog posts talk about heat pumps as an expensive, rising cost. The redemption data says the opposite is closer to true, at least in aggregate.

One separate, older estimate is worth naming here because it still circulates widely. The Energy Saving Trust puts a typical air source install at around £12,000, a figure based on advisory modelling rather than actual claimed vouchers. It sits close to the official median, which is reassuring, but the two numbers are not measuring quite the same thing, so treat the redemption data as the sharper of the two when you want a real benchmark.

Why one quote lands at £13,000 and the next at £20,000

The heat pump unit itself is rarely what pushes a quote up. What moves the price is everything wrapped around it: pipework runs, whether your existing radiators need enlarging or replacing to work at a heat pump's lower flow temperature, and whether a hot water cylinder has to go in where a combi boiler used to sit. A well-insulated new-build with modern radiators can come in well under the median. An older solid-wall house needing a full radiator swap can run past £20,000 before you have counted the unit.

Property size plays its part too, but less than most people assume. A heat pump is sized in kW to match your home's heat loss, and a bigger house generally needs a bigger unit. Even so, the fabric of the building, not just its floor area, decides how much adaptation work follows. This is not covered by the Warm Homes: Local Grant, the means-tested route for insulation; that scheme funds a different mix of measures, and our heat pump cost breakdown sets out the components in full.

The size band where prices are moving the wrong way

Here is the detail most cost pages miss entirely. While the overall median barely shifted, the 4kW to 6kW band, the size that suits a flat or a small terrace, saw its price rise 11% year on year. At the same time, the share of installations at 12kW or larger has dropped from over 35% at launch to just 18% now.

Put those two facts together and a pattern appears. Smaller, urban properties are now the typical Boiler Upgrade Scheme customer, not the large detached homes that dominated the scheme's early years. Demand for small systems has grown faster than installer capacity to fit them cheaply, so the smallest band is the one where the price is actually climbing. If your home needs a compact unit, do not assume it will automatically be the cheap option.

Where the grant and the loan actually fit

The order matters more than people expect. The Boiler Upgrade Scheme grant is capital, taken off your quote before a penny changes hands. It is not means-tested, and it is your installer, not you, who submits the claim. Whatever remains of the £13,041 median, once the grant has landed, is what the Warm Homes Loan exists to cover, up to £20,000 for an air-to-water system.

The loan itself carries a second discount. The government pays your approved lender a grant of up to 20% of the loan, which cuts the rate you are quoted by up to around 5 percentage points, repayable over 3 to 10 year terms. Public loans are expected from September 2026. For the full grant-then-loan arithmetic on a typical balance, our heat pump loan and grant maths guide works through the monthly numbers, and the Boiler Upgrade Scheme stacking page covers the claim process itself.

One scope note worth being blunt about: this cost data and every loan cap above cover air-to-water heat pumps, the type that heats radiators and hot water through your existing wet system. Air-to-air units, which just blow warm air around a room, are not funded under the Boiler Upgrade Scheme or the Warm Homes Loan, and quoting one against the other is a common mix-up in general searches.

What the price actually buys

The £13,041 median is not simply a bigger number than a gas boiler quote for its own sake. A well-installed air source heat pump produces roughly three units of heat for every unit of electricity it consumes, according to the Energy Saving Trust, which is the efficiency edge that makes the running cost side of the calculation competitive even though electricity is priced higher per unit than gas. That comparison is its own worked calculation and deserves more space than one section here, but it is the reason the up-front number is not the whole story.

What it does mean for the cost decision is this: the size and adaptation work you pay for now largely set your running costs for the next fifteen years or more. A heat pump specified too small, or fitted onto radiators never upgraded for it, will cost less today and more every winter after. Our green home improvement loan comparison and the wider home energy grants map are useful next reads if you are weighing a heat pump against other retrofit spending on the same property.

Common questions

Start from £13,041, subtract the grant your fuel type qualifies for, and you have a realistic balance before a single installer walks through your door. That is the number worth checking your own quote against, not a rounded guess from a page that has never looked at the redemption data.