The big switch from gas boilers to air source heat pumps is underway!

The Boiler Upgrade Scheme – Ofgem has now started accepting £5K vouchers for the purchase and installation of Air Source Heat Pumps – backdated for installations from 1^st April 2022, so long as the installer was registered to receive these vouchers. The scheme is called the ‘Boiler Upgrade Scheme’ (although ‘Heat Pump installation Scheme’ would be a better description!)

This is the first step the UK Government is taking to get homes (and small businesses) heated by an efficient electricity source rather than by high carbon gas boilers. Gas boilers are responsible for air pollution in homes too, causing ‘tens of thousands of early deaths a year in the UK’ (Guardian 29/09/21), so switching is better for your family as well as the planet.

So what do you need to know about Air Source Heat Pumps and the BUS scheme?

What is an air source heat pump?

The Energy Saving Trust explains how they work

Gas is a fossil fuel building up a blanket of greenhouses gases destroying our precious planet. Air source heat pumps use about a quarter of the kWhs to heat your home and hot water, so, particularly where the electricity is from renewable sources, air source heat pumps cut your carbon footprint significantly.

The official guidance for property owners is at BUS Property owner guidance (ofgem.gov.uk) The scheme is open to individual or company property owners including landlords, second home owners and small businesses – only limited by (high) heat output limit. New builds are only eligible if the owner owned the land before the build (“self build”) and is an individual not a company. Other new builds and social housing are not eligible for the BUS scheme, as they are subject to other schemes. Ground source heat pumps are also eligible and get a £6K discount, but they cost more and require significantly more land. Note biomass boilers are eligible, but only in rural areas.

Common questions

Octopus Energy is being proactive in boosting the air source heat market and CEO Greg Jackson busts many myths surrounding air source heat pumps – such as too expensive, too noisy, too much disruption etc in this video:

Do air source heat pumps work in this country?

Most people in the UK are used to their central heating gas boilers, but air source heat pumps have been used for years in much colder countries than ours. They do need to heat a property that does not leak all its (expensive) heat out.
The best approach is to tackle Insulation, Double Glazing, Draft proofing. Note that it is only the loft and cavity wall insulation that is the pre-requisite for the BUS grant. EPCs don’t suggest ASHP and the prices and paybacks they quote for suggested measures may be inaccurate.

Could an air source heat pump be suitable for your property?
The GLA has a document looking into all the typical property types in London their clean heat options including calculations of whole life cost comparisons is here, which accompanies the study of the roll out of “Heat Pump Retrofit in London v2” here .
Consider these questions:
- Do you own the property – whether you live there, rent it out or run a business there
- Is there room for a large cylinder inside?
- Is there a position outside at least 1 metre from the boundary property and with 1.5 metre in front to expel cold air?
- If a possible position is on a roof it must be at least 1 metre from the external edge of the roof
- If a possible position is on a wall it must not be a wall that fronts a highway or be higher than above the level of the ground storey.
- Is the property a listed building or a scheduled monument? – not permitted
- Is the property within a Conservation Area or World Heritage site? – is there a position that does not front a highway or be nearer to any highway which bounds the property than any part of the building?
- Would the ASHP affect the external appearance of the building and its effect on the amenity of the area?
Talk to the possible installers about suitability, but many of the factors above relate to planning permission and building regulations if you would like to study yourself. is here.

Does an air source heat pump cost more than a boiler to buy?

Yes – hence the BUS scheme to reduce the price to be nearer the cost of a new boiler.
Octopus is working to use the BUS scheme to overcome that and has announced that “The cost of a new Octopus Energy installed heat pump should be in line with the cost of a new gas boiler”. Applications to be in the queue for one is here. As for any other home improvement or maintenance the home owner needs access to funds – as they do for new kitchens, bathrooms etc.

Does an air source heat pump cost more than gas central heating to run?

The cost of electricity and gas is volatile – unaffordable for many now. As a rule of thumb an air source heat pump uses 1/4 to 1/3 the kWh of a gas boiler, and, as electricity tends to be 1/4 to 1/3 of the cost of gas per kWh, the running cost should be comparable. Innovation is looking at ways to use more electricity when there is plenty in the system and less when there is high demand (eg 7pm-10pm) to bring down the cost. Having solar panels also cuts the cost during sunny times.
The Energy Savings Trust has a chart here comparing the cost of heat for an average property.
Figures are based on fuel prices as of April 2022. Negative fuel savings indicate a fuel bill increase. The saving you can expect will depend on the size of your home, any heating system upgrade and fuel type being replaced. You can expect the saving to range between old and new, depending on the age of your current heating system.
Octopus Energy here says “We’re also testing and trialling how heat pumps can be integrated with innovative smart tariffs like Agile Octopus to get even cheaper running costs….. We’ve found customers on a smart tariff can save around 30% on their bills by running their heat pumps in the greenest, cheapest periods of the day.”

Is there a lot of disruption to replace a boiler with an air source heat pump?

Air source heat pumps can use a variety of ‘emitters’, including underfloor heat (very efficient) and air (which can be reversed to provide cooling) as well as radiators. For replacing gas boiler systems the job will often need the replacement of some radiators – though in situ, so no taking up floors. And there will be no heat for a few days while the work is done. So less disruption than a kitchen replacement.

Steps to check out an air source heap pump 'boiler upgrade' If the answers to these questions lead you to be interested in an air source heat pump follow these steps:

Step 1 – talk to installers.

(See below re industry installer issues.) Finding an installer you trust and is willing to consider your job can be a challenge. And there can be a led time of months to source heat pumps – hence the need to look into heat pumps BEFORE your boiler dies. To get the BUS voucher the installer needs to be registered with Ofgem, as well as being MCS registered. To find an installer try:

There is no public list of installer who are registered with Ofgem to handle Boiler Upgrade Scheme vouchers – so the first thing to check is that the installer is registered to handle BUS vouchers.

Step 2 – check your EPC

The property must have an Energy Performance Certificate (EPC), less than 10 years old and with no outstanding recommendation for loft or cavity insulation. Your EPC will be here with a post code search. There are many sales channels that direct you to qualified EPC providers, but you can ask the installers you are considering to put you in touch with one they work with.

If your EPC recommends Loft or Cavity Wall Insulation you must get this done before being eligible for the BUS £5K and would then have to get another EPC done that no longer requires these.,

Your EPC might recommend other measures to reduce your carbon emissions. Any of these that reduce heat loss are worth doing if possible eg double glazing, whether or not you proceed with an ASHP, because that will reduce heating bills and carbon emissions. See CSE link at further references.

Step 3 – get 2 or 3 installers to quote.

Study the quote. Check that the £5K BUS grant has been deducted. Check the suggestions for radiator replacement carefully and whether you are happy with the position of the ASHP and cylinder. Check that the quote includes a good method of removing the condensate water that flows from the base. Consider the opportunity for smarter controls to set your required temperature and standard hours of operation for hot water and heat (such as Hive etc)

Step 4 – your installer will manage the process

Your chosen installer will apply to Ofgem for a BUS voucher and Ofgem will write to you to confirm that you plan to have the work done and that you are willing to allow an audit inspection if required.

So, if you own a property with a boiler that might not last too long how to go about getting an air source heat pump with £5K off?

Now is the time to get active before a winter (of discontent), because there is shortage of qualified Air Source Heat Pump engineers and a long lead time for the Air Source Heat Pumps themselves. The BUS scheme is first come first served within the budget, so, if your boiler might break down any time soon, the sooner the better.

The Tom Kiss case study

The case study here is for an installation at a terraced Victorian house one year on. Be aware that the installation is receiving ‘RHI’ payments from Ofgem that have been replaced with this ‘Boiler Upgrade Scheme’ since April 2022.

And see a variety of case studies at the Heat Pump Association web site here.

Decarbonising the UK’s heat

The challenge to decarbonise UK heating - click

The government’s recent 10 point plan for a green industrial recovery forecasts at page 24 that by 2028, 600,000 heat pumps will be installed each year, so the Boiler Upgrade Scheme (AKA Low Carbon Heating installation scheme) is the first step.
The way we heat our homes is going to change considerably over the next 10-15 years. To reach the government’s target of net zero carbon emissions by 2050, we will all need to stop using gas for heating, and the Committee on Climate Change is recommending here (p22) that government bans the sale of new gas boilers from 2033. The replacement is likely to be a mixture of heat pumps, electric heating and district heating. Page 70 estimates that, with a ‘Balanced Pathway’, growth of ASHP installation must rise from 26,000 a year currently to homes to deployment of 1million a year by 2030 (including in new build homes). However it does expect large proportion of these to be installed in off the gas grid homes.
In the 2020 UK Citizens Assembly report, 80% of people supported heat pumps as part of the solution to decarbonising homes
Can we scale up that much?
We did it before
From 1967 for ten years we converted all UK gas supplies from ‘town gas’ made from coal to gas from the North Sea gas. Every appliance that ran on gas (cookers, the odd fridge, water heaters and so on needed altering to be able to use the new type of gas. It kick started the trend for homeowners to get central heating, when they needed to pull up their floorboards if they wanted this new new fangled luxury. Installation of an air source heat pump can be less disruptive!
https://gas.retropia.co.uk/ explains to householders what would happen when this massive programme came their way. And this slide documents some of the complaints!
The Committee on Climate Change “The Development of trajectories for Residential Heat Decarbonisations to inform the Sixth Carbon Budget” here and includes this scenario at page 30.
And we can do it again –
For the 2020s scale-up the Committee on Climate Change here at page 70 asks for the UK Government to “provide a stable long-term policy framework to support sustained growth at sufficient scale” (i.e. 600,000 heat pumps per year in existing homes by 2028).
As well as bringing down the cost with the BUS scheme the Government needs to “build supply chains and new markets for low-carbon consumer offerings (e.g. electric cars and heat pumps) so that these can scale from being niche offerings to dominate the market and fully push out high-carbon alternatives by 2030 or soon after.” The immediate obstacle is the shortage of ASHP engineers.

The training and supply chain challenge - click

There is already a shortage of ASHP engineers, and most of the ASHPs and other equipment comes from outside the UK – with no visible policy to support this industry in the UK. The Heat Pump Association published ‘Transforming Britain’s Heating’ in June 2022 with the first pillar as ‘Creating a Highly Skilled Heat Pump installer workforce.’ This will include retraining existing heating engineers and , crucially, compensating them for the cost of training.
Pre-empting central initiatives Octopus is one company working on its own heat pump products and training ‘an army of 1,000 green heat engineers (double the current UK capacity)’. The Octopus video at ‘Common Questions’ above has a tour of their Heat Pump R&D and Training Centre. Octopus is also ‘working with manufacturers to strategically source key components and a build a much more efficient supply chain, which will help to slash material costs.”

Are there Co-benefits when we switch to ASHP?

One benefit is the reduction in health problems caused by (particularly old) boilers. There is also a value from being able to harness flexibility to programme heat and hot water production when there is plenty of low carbon electricity, and to produce less when there is a shortage – reducing the need for standby power ‘when the wind isn’t blowing and it is dark’. The Carbon Trust/Imperial College report on this has projected a value from flexibility of £16.7bn per annum by 2050.

Further References

Retrofit Advice from the Centre for Sustainable Energy – https://www.cse.org.uk/news/view/2687

Timeline for no more new gas boilers after 2025 – Heat Pump Association – https://www.heatpumps.org.uk/no-new-conventional-gas-boilers-in-homes-after-2025/

A Heat Pack for domestic consumers from the UK Power Networks – https://innovation.ukpowernetworks.co.uk/wp-content/uploads/2022/02/UK-Power-Networks-Heat-Pack-Domestic-Consumers-February-2021.pdf