Choosing to switch to an air source heat pump is a huge decision. With a range of factors to consider from brand, sizing and heat loss calculations, it can be difficult to know where to start. Our handy guide to heat pumps is here to take you through everything you need to know to help you choose the right heat pump for your home.
What Is an Air Source Heat Pump and How Does It Work?
An air source heat pump (ASHP) is a low-carbon heating system. It works by extracting warmth from the outside air and uses it to heat your home and hot water. The process works similarly to a refrigerator, but in reverse. The unit draws in outside air and passes it over a refrigerant, which absorbs the heat and compresses it to raise the temperature further. That heat is then transferred into your central heating system and hot water cylinder to create a reliable source of heat.
Despite the popular myth that heat pumps don’t work in the cold, even in the miserable UK weather, there is enough thermal energy in the air for a heat pump to run efficiently. In fact, Norway has one of the highest percentages of heat pumps in use per capita with more than 60% of homes having a heat pump – a country famously far colder than the UK.
Why More Homeowners Are Making the Switch
Heat pumps have become an increasingly popular choice for homeowners across the North West and the rest of the UK.
Here’s the top 5 reasons to switch to a heat pump:
- They run entirely on electricity – Whilst electricity is presently more expensive than gas, heat pumps produce far more heat per unit of electricity used than a gas system. As the UK moves closer to fully green energy, the cost of running a heat pump will only reduce over time. This also makes them an excellent option for homes that have solar panels fitted. If you’re generating your own electricity, you can power your heat pump at little to no cost, cutting your bills down to next to nothing.
- They’re eco-friendly – Heat pumps don’t burn fossil fuels, so they produce far fewer carbon emissions than a gas or LPG system. As more people look for ways to reduce their household carbon footprint, heat pumps help to cut your environmental impact whilst also reducing bills.
- They remove your reliance on oil or LPG – If your home is off the gas grid and you rely on LPG or oil, switching to a heat pump gives you a consistent heat source that’s protected from volatile fossil fuel prices. You’ll also never have the headache of arranging a fuel delivery again.
- They’re low maintenance – Heat pumps are easy to take care of and have a longer lifespan than a traditional boiler. A heat pump usually only needs a service once a year and has an average lifespan of 15-20 years, whereas a boiler has an average lifespan of around 10 years.
- There are grants and incentives available to support the switch to heat pumps – A major reason why many people are switching is the UK Government’s Boiler Upgrade Scheme (BUS) which currently offers a grant of £7,500 towards the cost of installing an air source heat pump for eligible homeowners in England and Wales. Homes currently heated by oil or LPG will benefit from a temporary uplift, with a £9,000 grant available from 21 July 2026 to 31 March 2027, meaning now is the best time to switch if you’ve been on the fence. The grant is directly applied to the cost of your installation leaving the remaining balance to be paid. There are also several green home incentives and loan schemes available from major UK banks like Halifax, Nationwide, Lloyds and Barclays that can provide additional support towards the remaining value of a heat pump, massively reducing your out-of-pocket costs.
What Types of Properties Can Benefit from a Heat Pump?
One of the most common misconceptions about heat pumps is that they are only suitable for newly built homes.
The truth is that almost any home can benefit from a heat pump. Flats, terraces, semi-detached and detached homes can all be suitable for a heat pump, provided the property is well insulated and the system is correctly sized. The type of property doesn’t matter so long as you have space to house a heat pump – for a flat, this may mean communal heat pumps for the whole building, a wall-mounted unit, or having your heat pump on a balcony.
The age of your home is less important than you might think. This misconception has come about because modern homes tend to come with better insulation built in as standard, but an older property that has been properly retrofitted with good insulation can be just as suitable. The age of your home is less important than many people think because the key assessment that determines heat pump suitability is a heat loss calculation. This is a professional survey that looks at your home’s floor area, the materials used in its construction and the quality of its insulation and glazing to calculate exactly how much heat your home loses and how much output your heating system needs to provide.
Two homes of the same size but with different levels of insulation may require different size heat pumps and will have different heating costs. This rule doesn’t just apply to heat pumps – even with a gas boiler system, a well-insulated home will always be cheaper to heat than a poorly insulated one.
How to Choose the Right Size Heat Pump for Your Home
When we refer to the “size” of a heat pump, we’re talking about its output in kilowatts (kW) rather than its physical dimensions. An undersized heat pump will struggle to heat your home efficiently, meaning it will consume more energy and cost more to run. An oversized heat pump will heat your home too much, causing it to turn off and on frequently (a process called short cycling). Because heat pumps are designed to stay consistently on at a low temperature, short cycling wastes energy and reduces the lifespan of your unit.
For most homes, heat pump sizes typically range from 4kW -16kW. Choosing the right size heat pump is essential and the exact size needed can only be determined by a heat loss calculation during the survey, but you can generally estimate a rough size based on the number of bedrooms.
Here’s a general guide to choosing the right size heat pump by number of bedrooms:
| Number of bedrooms | Approximate heat pump size |
| 1 | 3-4 kW |
| 2-3 | 5-8 kW |
| 4 | 9-12 kW |
| 5+ | 12-16 kW |
These figures are only a starting point; two homes with the same number of bedrooms can have very different heating requirements depending on factors such as insulation quality, window types, and overall energy efficiency.
If your home also has multiple bathrooms or you have a large family that uses a lot of hot water, you may need a larger heat pump to keep up with the demand. Your installer may recommend a hot water cylinder or buffer tank to support the system and ensure your home always has hot water on demand.
A common mistake is guessing based on your existing boiler size. You can’t accurately determine your heat pump size from your boiler because gas boilers are designed to produce quick heat at high temperatures, whereas heat pumps operate at lower, steadier flow temperatures. This is also why heat pumps often work best alongside larger radiators and underfloor heating.
Professional Assessment
Whilst the information in this guide is a good starting point, the only accurate way to determine the right heat pump system for your home is with a full heat loss survey carried out by a qualified installer.
At NxtGen Heat, our experienced engineers carry out thorough assessments before recommending any system. With over 20 years of experience, we can choose and install the right system for your home and provide ongoing support, repairs and annual servicing for your heat pump.
We also offer 0% APR finance options through our finance partner to help make your upgrade more manageable.
Get in touch to find out if a heat pump is right for your home. Our expert team of installers offers coverage across the North West including Preston, Chorley, Leyland, Wigan, Warrington and St Helens.
