Heat Pumps for Flats

Heat Pumps in Flats: It's Complicated, But Not Impossible

Right, let's be straight with you. Installing a heat pump in a flat is harder than in a house. There are real barriers: some logistical, some legal, some practical. But it's not impossible, and for some flats it's actually straightforward. Let's work through the honest picture.

The Three Main Challenges

1. Freeholder Permission

If you own a leasehold flat (which most flats in the UK are), you almost certainly need your freeholder's permission before installing anything on the building's exterior. This includes the outdoor unit of an air source heat pump. Some freeholders are accommodating; others aren't. Some management companies charge for the privilege of even asking. This isn't a technical problem, but it's a very real one, and it's worth sorting out before you spend any time planning the technical side.

2. Where Does the Outdoor Unit Go?

Air source heat pumps need an outdoor unit (roughly the size of a large washing machine) that draws in outside air and extracts heat from it. In a house, this goes in the garden. In a flat, your options are:

• Balcony: works if you have one and it's large enough. The unit needs clearance around it for airflow. Small balconies may be too tight.
• Wall-mounted: some units can be bracket-mounted on an external wall. Structural and aesthetic considerations apply, and you'll need freeholder agreement.
• Communal area: in some buildings, there's space in a communal courtyard or plant room. Needs freeholder and potentially other residents' agreement.
• Ground level (for ground-floor flats): if you have a small garden or terrace at ground level, this is often the easiest option.

3. Noise in Close Proximity

In a flat, you're physically closer to your neighbours than in most houses. Modern heat pumps are quiet, but they do make noise, a constant low hum during operation. If the outdoor unit is going on a balcony shared with bedrooms on either side, or right outside someone's window, this needs careful thought. Permitted development in England is conditional on the installation meeting the MCS Planning Standards sound calculation (MCS 020 a), assessed at the nearest neighbouring habitable-room window, and passing that in a dense block is a lot harder than in a garden. Ask for the completed calculation, not a reassurance.

Air-to-Air Units: A Partial Solution

Air-to-air heat pumps (essentially heat pump-powered air conditioning systems) don't need a hot water cylinder and don't connect to your radiators. They heat and cool the room directly through wall-mounted indoor units. They're far easier to install in flats: the outdoor unit is smaller, the pipework is simpler, and they're widely used in Europe and Asia.

The downside is that they don't heat your hot water, so you still need another system for that. They aren't a full replacement for a central heating system. They are a genuinely useful option if your flat's hot water is already on an immersion heater or a communal system.

On the money: air-to-air now gets £2,500 from the Boiler Upgrade Scheme, less than the £7,500 for an air-to-water system but not nothing. Note what it doesn't get: the extra £1,500 for oil and LPG homes off the mains gas grid applies to air source and ground source heat pumps only, not to air-to-air.

Communal Heat Pump Systems

This is where things get more interesting. An increasing number of blocks (particularly new-builds and social housing developments) are being fitted with communal heat networks where a single large heat pump (often ground source) serves the entire building. Each flat has a heat interface unit (HIU) instead of a boiler.

If you're buying into a new development, check whether it has or is planned to have a communal heat network. If you're in an existing block and interested in this approach, it requires building-wide agreement and significant capital investment. It's a project for a residents' management company or housing association, not an individual leaseholder.

Ground Source Loop Sharing

For blocks with suitable land (unlikely in urban settings, more possible for low-rise rural developments), a shared ground source heat pump loop can work well. Again, this is a whole-building project, not an individual installation. But it's worth knowing the option exists if you're in a position to lead a building-wide upgrade.

When a Flat Genuinely Isn't Suitable

Some flats just aren't suitable for an individual heat pump installation right now. If you:

• Have no outdoor space at all and no suitable wall or balcony
• Have a freeholder who refuses permission
• Are in a high-rise block where noise and unit placement are genuinely unresolvable

...then an individual heat pump isn't viable for you at the moment. That's the honest answer. Pushing ahead anyway leads to a poorly installed system that will cause problems. It's worth keeping an eye on communal heat network options, and, if you're in social housing, asking your landlord about the Warm Homes Social Housing Fund, which is the current government programme for upgrading social housing stock.

When a Flat Can Work Well

On the other side, these flat types are often good candidates:

• Ground-floor flats with a private garden: often the easiest installation of all, similar to a small house
• Purpose-built flats with large balconies: enough space for a compact unit with proper airflow
• Flats in buildings with sympathetic freeholders or residents' management companies
• Flats where hot water is already communal: an air-to-air unit covers the heating side neatly

Costs for Flat Installations

Air-to-water (a proper heat pump on your radiators and cylinder): £9,000 to £13,000 installed, the same as a house, because the kit is the same. The Energy Saving Trust puts a typical air source install at around £12,000. Minus the £7,500 grant, that's £1,500 to £5,500 net. This only works where the outdoor unit placement is genuinely viable.

Air-to-air: considerably less, because there's no cylinder and no wet system, and the £2,500 grant covers a decent chunk of a single-room install. Nobody publishes a reliable UK average for these, so get three quotes rather than trusting a figure off a comparison site, including ours.

Communal systems: the cost per flat depends entirely on the building, the existing infrastructure and the heat source, and there's no published per-dwelling figure worth quoting. These are funded through service charges or through government programmes aimed at social landlords, not by individual leaseholders writing a cheque.

The grant rules that catch flat owners out

Straight from gov.uk, because these are the ones people get wrong:

• You must own the property. A leaseholder does. You'll still need freeholder consent for the works themselves, which is a separate hurdle.
• You must be replacing a fossil fuel heating system, and gov.uk lists "oil, gas, electric or LPG". Electric storage heaters and panel heaters count, which catches a lot of flats.
• Social housing cannot get a BUS grant. If you're a social tenant this is a conversation with your landlord, not an application you make.
• There is no EPC requirement and no insulation requirement. Both were removed. If an installer tells you otherwise, they're out of date.
• Once a voucher is issued it expires three months later, and Ofgem won't accept an application for a system commissioned more than 120 days earlier. In a block where you're waiting on freeholder sign-off, both of those are a real constraint. Get the consent first.

What to Do Next

• Check your lease for restrictions on alterations to the building exterior
• Contact your freeholder or managing agent early, before you spend any money on surveys or quotes
• If you have outdoor space, get an MCS-certified installer to assess whether unit placement is feasible
• If you're in social housing, ask your landlord about heat pump upgrade programmes. Many housing associations are actively running them

More reading: Boiler Upgrade Scheme: who qualifies | Heat pump installation costs