Frequently asked questionsHelping you understand

Yes. Heat pump technology is able to turn one unit (or kWh) of electricity into 3-4 units of heat energy, which is why they are 300-400% efficient.

Gas boilers are only about 85% efficient, which means one unit of gas converts to less than 1 unit of heat energy in the home.

If you currently use 10,000kWh of gas for heating and hot water, you will only need around 2,500kWh of electricity to get the equivalent amount of heating and hot water from a heat pump.

If you own your home and have a garden, you can fit a heat pump. The outside unit can go in the garden, on a flat roof and or up a wall. In the UK heat pumps typically work with existing radiators, these are called air to water heat pumps, but can work via blown heaters, known as air to air heat pumps. Air to water heat pumps qualify for a £7,500 grant but air to air heat pumps do not.

The average cost of a heat pump is £13,500 reducing to £5,000 after the Boiler Upgrade Scheme (BUS) grant of £7,500.

Typical installation costs are between £11,000 - £15,500, reducing to £3,500 - £8,000 after the BUS grant. Around 5% of installations are below £10,000 and 26% of installations are over £15,000 (before the grant is applied).

Lower cost installations will take place in smaller homes, with a lower heating demand and fewer internal changes. Higher cost installations will require a larger heat pump, radiator changes and a new hot water cylinder.

A heat pump system is made up of an external unit (aka the compressor) plus internal equipment.

The size of the external unit can vary depending on the kW output needed for the home. All outside units need some space behind them and about 1m in front.

Small units of 4-6kW (suited to smaller/well insulated homes) will typically be 1m wide x 1m high and 0.45m deep. About the size of a radiator, but deeper.

Larger units up to 15kW (needed for larger/less insulated homes) will typically be higher at 1.5m (about the height of a wheelie bin) whilst the width and depth stays about the same.

The internal configuration can vary as manufacturers strive to find solutions for all homes.

Some heat pumps only need a hot water cylinder inside. Others need either a wall hung boiler-sized unit plus a hot water cylinder OR fridge-freezer sized unit that includes the hot water cylinder.

The short answer is no, heat pumps will work in all homes and all ages.

Insulating as much as possible is important for reducing how much energy you need to buy to heat your home, which means lower fuel bills, but it is not critical for fitting a heat pump.

However, adding insulation can also reduce the cost of installing a heat pump, as better insulation can mean fitting a smaller unit with fewer radiator changes. Effective, low cost insulation measures are loft insulation to 300mm depth and cavity wall insulation.

Where all practical insulation measures have been applied, radiators can get bigger to compensate for a higher heat loss. To put it another way, you can still achieve an efficient heat pump system and warm home in older, less insulated properties.

Where your home is poorly insulated and smaller existing radiators are left in place a heat pump can still work. Many standard heat pumps will operate up reasonably efficiently to 70°C as standard (the same as a gas or oil boiler) but they will cost more to run.

What size heat pump you need will be based on a number of factors, including the size of your home, property type, insulation levels and where you are in the country.

Heat pumps are sized according to their kiloWatt (kW) power output. Domestic heat pump models range between 4-16kW.

We are used to seeing very large kW outputs for gas and oil boilers, however they are universally oversized and not a useful guide for heat pump sizing.

The average UK home needs a maximum of 6-8kW of power to keep their home warm on a cold day and most homes need less than 12kW, all comfortably within the capacity of standard heat pump models.

The Warmur calculator will provide you with an approximate heat pump size. As part of the quote process for selecting the right sized heat pump, your installer will carry out a ‘room-by-room’ heat loss calculation in your home that will provide a more accurate heat pump size.

Most households benefit from changing one or two radiators, but really it depends on how efficiently you want the heat pump to operate.

But top-end efficiencies are achieved with extra large radiators, which means more of your existing radiators will need to be replaced, but this increases the installation cost significantly. As heat pumps get more efficient at higher temperatures, extra large radiators will become less important.

For low energy users, the extra upfront cost needed for a higher efficiency will not be recouped in energy savings. For high energy users on the other hand, the investment may be worth it.

Where it makes sense to do so, accepting a slightly lower efficiency will keep the installation cost down.

The best heat pump is a subjective question, because it will be the best heat pump for your circumstances.

Heat pump manufacturers are improving performance and efficiency all the time, even at higher operating temperatures. Picking the latest model with a high SCOP (seasonal coefficient to performance) is a great start, but only one part of the answer.

The installer you pick will ultimately determine whether your heat pump performs brilliantly or poorly. A good heat pump can perform badly if the installer lacks the skills to correctly design and optimise the system. We’ve built a network made up of the UK’s top installers to help households get the best performance from whichever heat pump they choose.

Finally, the footprint of the heat pump, internally and externally, varies and how much space you have inside and outside will influence which heat pump model is more suitable.

Noise is a near universal concern for households who understandably don’t want the noise of a machine humming in the garden.

The good news is heat pumps have got quieter with manufacturers adding more sound buffering to the inside of the unit and many advise they are no noisier than a fridge from five metres away. They will also be turned off in the summer when you are more likely to use the garden.

Anyone with a roof that is South or East/West facing (and any orientation in between) and can accommodate at least six panels should fit solar PV.

Solar is one of the most accessible renewable technologies available to households with minimum disruption and quick paybacks. For many households they are a great place to start their home decarbonisation journey.

The short answer is you should fit as many solar PV panels as possible on your roof. The bigger the array the quicker the installation will pay for itself as you can expect a combination of larger energy savings and a healthy payment for everything you send back to the grid.

A typical 8-10 panel array will provide 3,000-4,000kWh of electricity, depending on the angle of your roof and which direction it faces in. South facing is best, but anywhere from East to West is also good.

The average household will use around 3,000kWh of electricity a year and an 8-10 panel array would provide about 50% and any surplus electricity is sent back to the grid.

A typical heat pump installation or an electric vehicle will add another 3,000kWh to household use and will soak up 25% or more of surplus energy. The more electricity you can use directly in your home, the more money you will save.

Prices vary depending on the number of panels. A 6-panel array will cost around £4,500 while a 14-panel array will cost around £9,500 (this is excluding the cost of a battery).

Households can typically expect to recoup the upfront cost in 6-9 years depending on how much you can consume directly. Interest free finance is available from many solar PV providers.

This is a really tricky question because it depends on the size of your solar array, your heating system, if you’re home in the day and whether you have or plan to have an electric vehicle.

Batteries are more beneficial when you don’t have an electric heating system (e.g. a heat pump) or an electric vehicle, because there will be a lot more surplus that the battery can capture.

For more electrified households, their surplus storage benefits are reduced, but still available for maximising off-peak tariffs.

If you’re on a budget we recommend you de-prioritise a battery.

If you have a large solar array and no other ways of utilizing the surplus electricity, go with a larger battery.

If you have a small solar array or a large array with other storage options (hot water cylinder and/or EV) go with a smaller battery or no battery.

It’s often worth waiting to see how much electricity you send back to the grid and adding a battery later if it's significant. As standalone batteries now attract 0% VAT, so there is no cost downside to waiting 12 months.

If you live in England or Wales and are replacing an existing gas or oil boiler or electric heating system with an air source heat pump you will qualify for £7,500 grant. It is no longer necessary to install cavity wall and loft insulation to qualify for the grant. The grant only covers air to water heat pumps, i.e. those that work with radiators, and not air to air heat pumps. The grant does not cover 'hybrid' systems where a boiler provides back up to the heat pump.

We can arrange a Home Energy Passport survey within a week. Contact us to enquire about our services.