What Homes are not Suitable for Heat Pumps?

Air source heat pumps (ASHPs) are gaining popularity in the UK as a low-carbon alternative to traditional heating systems like gas boilers. They offer an energy-efficient way to heat your home and can even help lower energy bills in the long run. But while they’re a great fit for many properties, they’re not suitable for every home.

So, before you start applying for grants or booking an installation, it's worth understanding if your property is suited for one. In this blog, we’ll break down what air source heat pumps are, which homes they don’t work well in, and how you can make yours more compatible. We'll also go over grants available and answer a few common questions.

What Are Air Source Heat Pumps?

Air source heat pumps work by absorbing heat from the air outside (even when it’s cold) and using it to warm up your home and hot water. They run on electricity but are extremely efficient, generating around 3 units of heat for every 1 unit of electricity used. This makes them a great way to reduce your carbon footprint and become a greener home.

There are two main types:

• Air-to-water heat pumps, which heat water for radiators and taps.
• Air-to-air heat pumps, which blow warm air into rooms (a bit like an air conditioning unit in reverse).

They’re most effective in well-insulated homes and tend to work best with low-temperature heating systems like underfloor heating or larger radiators.

Which Homes Are Not Suitable?

Although heat pumps are being pushed as a key part of the UK's net-zero goals, not every home is quite ready for one. Here are some scenarios where a heat pump might not be suitable—at least not without some significant upgrades:

1. Poorly Insulated Homes

If your home is draughty or lacks proper insulation in the walls, floors, or loft, a heat pump will struggle to maintain a comfortable temperature. Unlike gas boilers that pump out high levels of heat quickly, heat pumps work gradually and need a tight building envelope to perform efficiently.

2. Very Small Properties or Flats

Heat pumps come with an outdoor unit, which requires good airflow around it to function properly. If you're in a small flat with no outside space or on a high floor, it may not be possible to install one without structural changes. Communal buildings like tower blocks also pose extra challenges.

3. Properties Without Garden or Yard Space

The external unit is usually placed in the garden, yard, or mounted to an outside wall. If your home lacks this space, fitting the outdoor unit could be difficult or unsightly—especially in terraced housing with no side or rear access.

4. Homes With Old Heating Systems

If your current system uses small, high-temperature radiators, you might need to replace them with larger ones or switch to underfloor heating to make a heat pump work effectively. This can be quite disruptive and expensive in older homes.

5. Properties With Single-Glazed Windows

Double glazing is another key to heat retention. If your windows let all the heat escape, a heat pump won’t be able to keep up, leading to chilly rooms and high electricity bills.

How Can You Make Your Home More Suitable?

If your home isn't quite ready for a heat pump, don’t worry. You might only need to make a few changes to get it there. Here’s a simple checklist to help:

• Insulate your loft – This is one of the easiest and most cost-effective upgrades.
• Add cavity wall insulation – Especially important in homes built after the 1920s.
• Upgrade your windows – Double or triple glazing will stop heat escaping.
• Seal draughts – Use draft excluders on doors, windows, and chimneys.
• Consider larger radiators or underfloor heating – Heat pumps work best with low-flow heating.
• Free up outside space – Clear a spot in your garden or yard for the unit, ideally close to where your current boiler is.
• Get an EPC (Energy Performance Certificate) – This will give you a good idea of what needs upgrading.

Details on the Grants Available for Getting a Heat Pump

To help more people make the switch, the government is offering financial support through the Boiler Upgrade Scheme (BUS).

Here’s what you need to know:

• Up to £7,500 is available towards the cost of installing an air source heat pump.
• You must own the property.
• Your home must have a valid EPC with no outstanding recommendations for loft or cavity wall insulation.
• New builds are not eligible unless self-built.
• The grant is paid directly to your installer, who will reduce your bill accordingly.

The scheme is part of the government’s push to decarbonise heating, and it’s expected to run until 2028. Funding is limited, though, so it's worth getting in early.

Final Thoughts

Air source heat pumps are a solid choice for sustainable home heating, but they’re not a one-size-fits-all solution. Homes that are poorly insulated or lack outdoor space may not benefit from them without significant upgrades. However, with the right improvements—and some help from government grants—it’s possible to make most homes more heat-pump friendly.

If you're unsure whether your property is suitable, speak to a qualified installer who can carry out an assessment and advise on the best route forward.