How heat pumps work in flats and apartments differently from houses
Air-source heat pumps extract heat from outside air to warm your home and hot water, even at temperatures as low as -15°C (Energy Saving Trust, 2026). In a flat, the main difference from a house is where you put the outdoor unit. Your options are usually a balcony, an external wall bracket, or a communal rooftop if the freeholder agrees.
Heat pumps operate at lower flow temperatures (35–45°C) than gas boilers (60–70°C). That means your existing radiators may need upgrading to larger ones, or you may need underfloor heating, to deliver the same warmth. The system also uses a reversing valve to provide cooling in summer, which is a practical bonus for flats where opening windows is limited by noise or security concerns.
Indoor space is another constraint. A heat pump needs a hot water cylinder, typically 180–210 litres, which takes up floor space in a cupboard or utility area. In a small flat, that can be a challenge.
Flats need a heat pump – the eligibility checklist
Before you start, check these four conditions. First, you need adequate space for an outdoor unit at least 1 metre from windows and boundaries. Second, the flat must have at least a C-rated Energy Performance Certificate (EPC) to meet Boiler Upgrade Scheme grant requirements (GOV.UK Boiler Upgrade Scheme eligibility, 2026).
Third, if you own a leasehold flat, you must get written permission from the freeholder or management company before any work begins. Fourth, the property needs sufficient insulation – cavity wall, loft, or solid wall insulation to at least 100mm – to make the heat pump efficient (Energy Saving Trust heat pump suitability checklist, 2026).
If your flat fails any of these, a heat pump may not be practical or grant-eligible. A gas boiler or electric heating might remain the better option.
Quick numbers – heat pump cost, savings, and grant for flats
| Item | Typical figure (2026) |
|---|---|
| Installation cost (air-source, typical flat) | £7,000–£13,000 |
| Gas boiler replacement (like-for-like) | £1,500–£4,000 |
| Annual running cost saving vs gas (typical 2-bed flat) | £200–£500 |
| Boiler Upgrade Scheme grant amount | £7,500 (from April 2026) |
| Average heat pump lifespan | 15–20 years |
| Typical flat heat pump size | 5–8 kW |
The grant figure comes from the Boiler Upgrade Scheme (GOV.UK, DESNZ 2026). The cost and savings ranges are based on Energy Saving Trust and MCS installation data (EST, 2026; MCS, 2026).
What is the real cost of a heat pump for a flat in 2026 (including grant)?
The Boiler Upgrade Scheme provides a fixed grant of £7,500 for air-source heat pumps, reducing your net cost to £0–£5,500 for a typical flat installation (GOV.UK, DESNZ 2026). Installation costs vary by flat size. A 1-bed flat might need a 5kW system costing £7,000–£9,000, while a 3-bed flat may need an 8kW system costing £10,000–£13,000.
Additional costs are common. New radiators or underfloor heating can add £1,500–£4,000, a hot water cylinder adds £800–£1,500, and an electrical upgrade may cost £500–£1,500. Running costs depend on electricity prices. At the October 2026 price cap of 24.5p/kWh (Ofgem, 2026) and a heat pump coefficient of performance (COP) of 3.0, heating a 70sqm flat costs about £600 per year compared to roughly £900 per year for gas. COP measures how many units of heat you get for each unit of electricity. A COP of 3.0 means 3 kWh of heat for every 1 kWh of electricity used.
Your actual savings depend on your flat’s insulation, the size of radiators, and your electricity tariff. Compare running costs of heat pumps vs gas boilers
Can you install a heat pump in a leasehold flat?
Leasehold flats require written permission from the freeholder or management company. Under the Landlord and Tenant Act 1985, you may need to serve a Section 19 notice to formally request consent for alterations (Leasehold Advisory Service (LEASE), 2026). The freeholder can refuse if the installation would cause structural damage, reduce property value, or breach lease terms on external alterations.
Some housing associations and councils have pilot schemes for heat pumps in flats. Check with your landlord directly if you are a social tenant. If permission is refused, you may need to pursue alternative heating options such as a high-efficiency gas boiler or electric storage heaters.
Guide to getting landlord permission for home energy upgrades
Which installers are certified for heat pumps in flats?
Installers must hold MCS (Microgeneration Certification Scheme) certification to install a heat pump eligible for the Boiler Upgrade Scheme (MCS, 2026). They should also be registered with TrustMark, the government-endorsed quality scheme for consumer protection (TrustMark, 2026). For electrical work, the installer must be registered with NICEIC or NAPIT under the Part P competent person scheme.
Gas Safe Register is not required for heat pump installation. However, if you are switching from gas, you must cap or remove the gas supply, which requires a Gas Safe registered engineer (Gas Safe Register, 2026).
How to verify a heat pump installer for your flat
Start by checking the MCS Installer Database at mcsdirectory.com for approved installers in your postcode (MCS, 2026). Ask for at least three quotes and compare them against the Energy Saving Trust’s typical cost range for your flat size. Confirm the installer has specific experience with flats, not just houses. Ask for references or case studies of similar installations.
Verify the installer’s public liability insurance, which should be at least £5 million. Check their TrustMark reviews for any complaints or unresolved issues. A good installer will walk you through the eligibility checklist and provide a clear written quote covering all costs, including any necessary radiator or electrical upgrades.
Frequently Asked Questions
Yes, if you have space for an outdoor unit on a balcony or external wall, a C-rated EPC, and permission from the freeholder. The Energy Saving Trust advises checking insulation and heating system compatibility first.
Installation typically costs £7,000 to £13,000 in 2026, according to MCS data. The Boiler Upgrade Scheme provides a £7,500 grant towards air-source heat pumps.
In most cases, no, as heat pumps are permitted development. However, leasehold flats require written approval from the freeholder or management company before installation.
Savings depend on your current heating system. Replacing electric heating can save £400-£600 per year, while replacing a gas boiler typically saves £100-£300 annually, according to the Energy Saving Trust.
A 5-8kW air-source heat pump is typical for a one- or two-bedroom flat. A certified installer should calculate the exact size based on your flat's heat loss and hot water demand.
