To help reach net zero by 2050, the government favours heat pumps as a low carbon heating solution, pledging to switch over to the renewable tech by 2026 instead of installing new gas and oil boilers. 

For the many homeowners and businesses asking, ‘is a heat pump worth it?’, we take a look at the pros and cons of off-grid energy options, including a breakdown of how heat pumps work.

What is a heat pump? 

Heat pumps are renewable, capturing heat from outside your home and transferring thermal energy inside, to heat your home and/or water.  

Heat pumps work by drawing in heat from the outside air, ground or water, depending on the type of heat pump, into a heat exchanger, which is known as an evaporator.  

In the evaporator, the heat causes a refrigerant to evaporate, then the evaporated gas goes to a compressor, where it gets condensed back into a liquid. This drives the temperature up and this heat is released and used to heat water or gets circulated around the central heating system to radiators and underfloor heating.  

There are two units which need to be installed, one outside and one inside the home, connected together via pipes. They can extract heat from temperatures as low as -15oC. 

Air source heat pumps draw heat from the air outside, ground source heat pumps draw it from underground, and water-source heat pumps draw heat from a water source, such as a lake, river, or the sea.  

If you are installing a water source heat pump, there are two types: open and closed loop systems.  

An open loop system will extract and filter the water, circulate it through the system and release it back into the water source or another alternative, such as a water well or borehole. These systems don’t use a heat transfer fluid – the water itself is the fluid that is circulated through the heating system.  

A closed loop system continually circulates a mixture of water and refrigerant (also known as a ‘brine’) through submerged or buried pipes. The water from the source doesn’t get into the pipes, and as the fluid flows through the pipes it is heated by the water body and returns to the heat pump. 

Heat pump benefits  

• Renewable and low-carbon 
• A great heating option for newer, modern homes and properties that are well-insulated 
• Suitable for use in underfloor heating systems, requiring a constant, relatively low ambient temperature 
• When installed in an energy efficient home, can mean with lower running costs for the property owner 

Heat pump drawbacks 

• Expensive to install, with a large upfront payment 
• Inefficient in poorly insulated homes, which are typically rural and off the mains gas grid 
• They provide a lower heat supply than boilers 
• They can be noisy 
• Installation can be disruptive and time intensive, requiring a large amount of outdoor space  

Heat pump costs  

The cost of a heat pump varies greatly depending on the type of heat pump and the property the technology is being installed within.  

The Boiler Upgrade Scheme also offers a grant of up to £5,000 to install an air source heat pump in homes in England and Wales.  

However, research has shown in rural off-grid properties, which are typically harder to heat, the cost of retrofitting a heat pump could be up to £32,000. 

Heat pump alternatives 

Renewable liquid gases are produced in the UK as a 100% renewable alternative to heat pumps and are highly suited to rural, off-grid homes and properties.  

Renewable liquid gases are chemically identical to traditional LPG, meaning they can be used within existing LPG heating system infrastructure, with no changes required to the equipment of household appliances.  

For rural homes already using LPG, this also means no up-front costs are incurred in switching over to renewable liquid gases. For properties heating their home and hot water with oil or solid fuels, a renewable liquid gas system takes just two days to install, and costs in the region of £2,000. 

For environmentally-savvy homeowners, renewable liquid gases offer up to a 90% emissions reduction than conventional LPG.  

Will a heat pump work for me?  

Installing a heat pump in a converted barn 

Rebecca Morgan is a homeowner who installed a new heat pump in 2013 and is positive about the renewable technology. “We live in a rural area, and we converted a barn, which is well-insulated, and has underfloor heating throughout.  

“A ground source heat pump made sense, and because we have a bit of land, we were able to install pipe work, and laid this ourselves,” explains Rebecca.  

“The pipe work is laid flat, because we have the space, but you can dig straight down – which is an option for those with less space. 

“We laid 800 meters of pipe work, which is more than we need for one barn, but we would like to convert another barn and install another heat pump in future,” says Rebecca. 

“The total investment was around £12,500, but we were able to take advantage of ‘Renewable Heat Incentive’ (RHI) payments then, and unfortunately these are no longer available.  

“However, we don’t have energy bills, apart from a small amount of electricity used, and we don’t need to order fuel. 

“It’s really efficient, and you don’t need an annual service, so we have been pleased with it,” adds Rebecca.  

When heat pumps won’t work 

Janice and Philip Whitelock live in a three-bed detached bungalow off the gas grid in Camelford, North Cornwall. 

They spent time exploring the best energy solutions for their bungalow and looked at the pros and cons of electricity, as well as air source heat pumps. They decided that electricity wasn’t a reliable enough option for them, and that heat pumps required too many alterations to the property, which is something they hadn’t budgeted for and weren’t prepared take on. 

Janice and Philip made the decision to switch to LPG as it was the most cost-effective option. Although renewable liquid gases weren’t available on the market at the time of install, their system would now be fully compatible with the renewable fuel.  

“Where we live, we have overground electric cables, and there is simply no guarantee that they will weather the storms we have around here,” said Janice. 

“We just don’t have the proper infrastructure for everything to be electric. All it needs is for one tree to fall, and we’d be out of power. That’s not reliable enough for us and we don’t want to live in fear of being cut off. 

“It [LPG] is a much more secure and economical solution for our home. Our bills are lower and we’ve cut our carbon. It makes us happy to know we’re doing our bit to help the environment. We know that renewable green gas is on the horizon too and it’s great to know that we’ve got the option to become greener in the future without having to change any of our heating set up.” 

Decarbonising domestic heating  

There is no silver bullet for decarbonising off-grid UK heating. Homeowners should research a mix of low-carbon heating options to find out which is most suitable for their preference, budget and property type.