An introduction to Heat Pumps

There has been a lot of talk recently about heat pumps.  They are a key part of the UK strategy to find a low carbon solution to home heating.  The Government has announced that the installation of new gas boilers will be banned from 2035, and set a target of installing 600,000 heat pumps a year by 2028 – a twenty-fold increase in the current rate of new installs.

In June 2022 the Government launched the new Boiler Upgrade Scheme, which gives a grant of up to £5000 towards the cost of installing a heat pump (find out more here).  

So what are heat pumps, how do they work, and how do you find out if they are the right option for you?

Heat pumps – the basics

Heat pumps are a well-established techology.  They extract heat from the surrounding environment and concentrate it so it can be used for home heating and hot water.  They work the same way as a deepfreeze, but in reverse – so you home gets warmer, and the outside environment gets a little colder.  The beauty is that for one unit of electricity put in you can get up to 3 or 4 units of heat out.  That’s why they are far more efficient than a regular electric fan heater or storage radiator.  And, yes, they do work in the middle of winter, provided your system is designed right – that’s why they are the No. 1 heating source in much of Scandinavia.

There are several types of heat pumps.  In a domestic context the main options are:

• Air Source Heat Pumps:  which take heat from the surrounding air for use in your home.  This article on the Energy Saving Trust website explains how they work, and describes the two main options:  Air to Water, and Air to Air.

• Ground Source Heat Pumps:  which extract heat from the ground, either through a buried coil near the surface or a deeper borehole.  Again, the Energy Saving Trust have a handy explanation.

There’s more information below but let’s start by asking why are we even thinking of heat pumps in the first place?  Well, obviously, it’s all about the carbon.

Zero Carbon Heating

The average house in the UK emits over 3 tonnes of CO2 a year, with the vast majority coming from our existing central heating and hot water systems.  If you are concerned about reducing your carbon footprint, this has to be one of the biggest elements to focus on.  In this video, Martin Philips and Phil Birch talk through the options for cutting that footprint – looking at insulation, solar panels, switching to a green energy supplier and installing a heat pump – or, ideally, a combination of all four.  

Everyone’s home and energy consumption patterns are different, so the precise numbers will vary.  This Background Note explains the assumptions used in the video and provides further details on the specifics.  It’s definitely worth a read if you’re interested in the numbers.

Case Study:  Installing an Air Source Heat Pump

Martin Philips lives in a house near Steyning, parts of which date back to 1480.  For some years he has been looking at ways to reduce his carbon footprint. After doing some research, in 2020 he installed an air source heat pump to replace an oil fired boiler.  He has been delighted with the results and produced this video to show others why he did it and how it worked out. 

Here’s some advice from Martin on points to bear in mind if you’re looking at installing a heat pump yourself.  

More information

There’s lots of information out there on heat pumps, some of it quite confusing and contradictory.  Installing one is a big investment so we recommend you read around and be sure to get several quotes before you make any decisions.  Here’s some sources we particularly recommend:

• The Heat Geek YouTube channel which offers technical advice on the intricacies of home heating and renewables.  Here’s one on questions to ask your heat pump installer to see if they know their stuff and help spot the cowboys.
• A special edition of the Fully Charged video series on Air Source and Ground Source Heat Pumps.
• A blog on the Octopus Energy website on How much does it cost to run a heat pump.  This makes the point that you need to choose the right electricity tarif if you are to keep your energy bills down.
• Advice from the Centre for Sustainable Energy on Air Source Heat Pumps and Ground Source Heat Pumps.
• A backgrounder from the Centre for Alternative Technology on Heat Pumps