Heat pump installation in the UK typically takes 2–3 days. But the preparation — heat loss surveys, system design, grant paperwork — matters just as much as the install itself.
Heat pump installation in the UK is a bigger project than swapping a boiler, but it needn’t be disruptive or mysterious. A professional job typically takes 2–3 days for an air source system in an average home, involves two or three engineers, and should leave you with a fully commissioned system and a warranty in hand. This guide walks through every stage — from your first conversation with an installer to the moment you turn the heating on — so you know exactly what to expect.
Before installation: the heat loss survey
A heat loss survey is non-negotiable — and by MCS standards it’s legally required before any BUS-grant-eligible installation. An engineer visits your home and calculates, room by room, how much heat your property loses at the design temperature (typically -3°C for most of England, colder for Scotland). This figure determines the size of heat pump you need.
Getting this step right is the single most important factor in a successful installation. An undersized pump won’t keep your home warm on cold days. An oversized one will short-cycle (switching on and off repeatedly), reducing efficiency and shortening the unit’s life. Be wary of any installer who quotes without a survey visit — this is a red flag that the system design will be guesswork.
The survey also assesses your current radiators. Since heat pumps operate at lower flow temperatures (typically 45–55°C vs a gas boiler’s 70–80°C), existing radiators may be too small to deliver adequate heat. A good engineer will calculate whether radiators need upgrading in each room, which directly affects your quote.
Choosing an MCS-certified installer
MCS (Microgeneration Certification Scheme) certification is the key quality standard for heat pump installers in the UK. Only MCS-certified installers can apply for the BUS grant, and only work done by MCS-certified installers qualifies the homeowner for any future grant or scheme that requires certification. Always verify certification at mcscertified.com before signing anything — entering a postcode brings up all certified installers within a chosen radius.
When getting quotes, aim for at least three from different companies. Compare:
- The heat pump brand and model specified (and whether it’s sized to the survey results)
- Whether the BUS grant is deducted and who handles the application
- Warranty terms on the unit and installation workmanship
- What’s included for radiator upgrades, hot water cylinder, and electrical work
- Whether commissioning and MCS certificate are included
The Which? guide to finding a heat pump installer has useful tips on spotting red flags in quotes and contracts.
Grant paperwork: what happens before work starts
If you’re claiming the Boiler Upgrade Scheme grant, your installer must submit an application to Ofgem and receive a voucher approval before installation begins. Work carried out before voucher approval does not qualify. The application process is handled entirely by the installer and typically takes a few days. Make sure you have:
- A valid EPC (Energy Performance Certificate) for your property
- No outstanding loft or cavity wall insulation recommendations on that EPC
- Agreed the contract and scope with your installer
Once the voucher is approved, installation can be scheduled. Vouchers are valid for three months, so there’s flexibility on timing.
The installation process: day by day
Here’s what a typical 2–3 day air source heat pump installation looks like for a 3-bedroom semi-detached home:
Day 1: preparation and outdoor unit
- Remove old boiler (usually takes 1–2 hours)
- Install outdoor unit on wall bracket or plinth — positioned for airflow and noise impact
- Run refrigerant pipework from outdoor unit to indoor location
- Begin plumbing work for indoor components
Day 2: indoor installation
- Install hot water cylinder (if new or replacement required)
- Connect heat pump to existing pipework and radiators
- Replace or upgrade radiators where required
- Install controls and thermostat
- Electrical work: new circuit from consumer unit
Day 3: commissioning
- Charge refrigerant circuit
- System pressure test
- Full system run-up and performance checks
- Installer walks you through controls and optimal settings
- MCS commissioning certificate issued
You’ll be without heating and hot water during parts of the install, but most installers schedule the work to minimise the cold period — often keeping a temporary supply running until day 3.
What disruption to expect
Heat pump installation is less disruptive than a full central heating installation but more involved than a boiler swap. Expect:
- Engineers in and out of most rooms if radiators are being checked or replaced
- Some drilling through external walls for refrigerant lines
- Possible disruption to airing cupboard or utility room space for the cylinder
- Brief loss of heating and hot water — usually less than 24 hours total
- Outdoor noise during fan testing on commissioning day
Groundwork for a ground source system is considerably more disruptive — horizontal loop installation involves excavating large sections of garden, which typically takes 1–3 days of heavy machinery work.
After installation: getting the most from your heat pump
Heat pumps work best when run continuously at a lower temperature rather than being switched on and off like a boiler. The most common mistake new heat pump owners make is setting high flow temperatures or using aggressive schedules — both of which hammer efficiency. Your installer should set the system up for low-temperature operation and show you how the controls work.
Key settings to understand:
- Flow temperature: aim for 45–50°C with adequately sized radiators, lower if possible
- Weather compensation: modern heat pumps adjust flow temperature based on outside temperature — make sure this is enabled
- Hot water schedule: heating water once or twice a day is more efficient than continuous reheat
The Energy Saving Trust’s heat pump optimisation advice is a useful resource for the first few months of ownership. Annual servicing is recommended to maintain efficiency and protect warranty terms. Our heat pump costs guide includes typical servicing costs, and our savings calculator can help you track whether your system is running to expectation.