Process and timeline
How long does an air source heat pump installation take?
Last updated: June 2026
In short
The short answer
Most homeowners are surprised by how quick the actual fitting is. For a typical three-bedroom home, the on-site installation of an air source heat pump takes two to five working days. The wider journey takes longer, usually four to eight weeks from your first enquiry to a commissioned, running system, because of the survey, the design work, ordering equipment and scheduling the install. Simple jobs in well-insulated modern homes are at the fast end, while larger period properties that need several radiators changed, or extra pipework, take a little longer on site. The grant paperwork runs alongside and does not usually hold up your heating. Knowing this timeline up front helps you plan, particularly if you are replacing a boiler that is on its last legs and want the new system in before winter.
Survey and design
Everything starts with the heat loss survey, the most important stage of the whole project. An installer visits your home and spends two to three hours measuring rooms, checking insulation, glazing and walls, and recording how the property is built. From that they calculate your heat loss and design the system: the size of heat pump, which radiators need upsizing, the cylinder, the pipework route and the target flow temperature. This design work is done off site over a few days to a couple of weeks, after which you receive a detailed quote and proposal. Do not rush this stage or accept a quote without it. The quality of the survey decides whether your heat pump is comfortable and cheap to run, or oversized and disappointing. It is also where comparing several installers pays off, since you can judge the thoroughness of each design.
Installation days
Once you have signed off the design and equipment is ordered, the physical install is booked, usually a couple of weeks out. Over the two to five days on site, the team mounts the outdoor heat pump unit on a base or wall bracket, fits the new hot water cylinder, runs the pipework and electrics, swaps any radiators that need upsizing, and connects everything up. There is normally a short window without heating or hot water while the old boiler comes out and the new system goes in, but a good installer plans this so you are rarely left cold overnight. The work is tidy and largely contained to the plant area, the cylinder cupboard and the radiators being changed.
- Day 1 to 2: outdoor unit, cylinder and main pipework.
- Middle days: electrics, radiator changes and controls.
- Final day: filling, testing and the heating changeover.
Commissioning and grant paperwork
On the last day the installer commissions the system, which means setting it up to run efficiently at the designed flow temperature, balancing the radiators, configuring the controls and showing you how to use it. Done properly, this is what delivers the efficiency the design promised, so it is worth the time. After that, the installer completes the MCS registration and submits the Boiler Upgrade Scheme paperwork to Ofgem so the 7,500 GBP grant is settled. This admin happens in the background and does not delay your heating, which is up and running from commissioning day. You should receive a handover pack with the MCS certificate, warranty details and commissioning records. Keep these safe, as you will want them for any future service, sale or warranty claim.
Plan ahead for winter
Because the full process runs four to eight weeks, start comparing quotes well before the cold months if you want your heat pump in before winter.
- System commissioned and balanced for efficiency.
- Controls explained and handover pack provided.
- MCS registration and grant paperwork completed by the installer.
The full timeline at a glance
End to end, expect a few weeks from your first enquiry to a running heat pump, with the on-site work itself usually 2 to 5 days. Most of the calendar time is the survey, design and scheduling that happen before anyone arrives to fit anything. The table below shows where the weeks go, so you can plan around a boiler that is on its way out or a deadline before winter. The exact timing flexes with how busy installers are and how complex your home is, but the shape stays the same: a short burst of work on site, wrapped in a longer run of preparation and paperwork. Comparing quotes early in the process gives you the widest choice of dates and the best chance of being warm before the cold sets in.
| Stage | Typical timing |
|---|---|
| Enquiry and comparing quotes | A few days to two weeks |
| Heat loss survey | Around half a day on site |
| Design and final quote | One to two weeks |
| Installation on site | Two to five days |
| Commissioning and handover | Part of the final day |
| MCS certificate and grant redemption | One to three weeks after |
Install days by property type
How long the team spends on site depends mostly on your property and how much pipework and radiator work it needs. A compact, well-insulated flat is quick; a larger detached home with several radiators to swap takes longer. The figures below are typical on-site install times once the design is signed off and the equipment has arrived. Underfloor heating retrofits sit well above the rest, because lifting floors and laying loops is slow work. Use these as a planning guide rather than a promise, since every home differs and your survey will give a firmer estimate.
| Property | Typical install time |
|---|---|
| Flat or small terrace | Two to three days |
| Three-bed semi | Three to four days |
| Larger or detached home | Four to five days |
| Underfloor heating retrofit | Longer, often a week or more |
Most of the time on site goes on pipework and radiators, not the heat pump itself. The outdoor unit and cylinder go in relatively quickly; it is the plumbing around them that fills the days.
What can delay an installation
Several things can stretch an install beyond the usual two to five days. Most are spotted at the survey, so they rarely come as a surprise on the day.
- Radiator and pipework upgrades that add days to the schedule.
- Electrical supply work, where the network operator may need notice before a larger unit can be connected.
- Siting near a boundary that needs planning permission rather than falling under permitted development.
- Manufacturer parts lead times on the heat pump or cylinder.
- Winter weather that slows or pauses outdoor work.
Most delays are foreseen at the survey stage, which is why a thorough survey matters. A good installer flags any of these early and builds the extra time into your quote and dates, rather than springing it on you mid-job.
Do you need planning permission?
In England most air source heat pump installs fall under permitted development, which means you do not need to apply for planning permission. That applies as long as the outdoor unit meets the size and siting limits, such as keeping it a set distance from a boundary and within the allowed volume. Within those rules, the job goes ahead without a planning application, which keeps the timeline short. Listed buildings and properties in conservation areas are the main exceptions, and may need planning permission or listed building consent before work can start, which adds time. Your installer confirms the position for your specific property before booking, so you are not left guessing. If consent is needed, factor in the council's processing time, which can run to several weeks on top of the usual schedule.