Replacing an older gas or oil boiler can feel like a major decision, particularly when you are weighing up installation costs against long-term savings. The connection between BUS and Ofgem is central to many heat pump upgrades: the Boiler Upgrade Scheme can reduce the upfront cost, while Ofgem administers the grant process. Understanding who does what makes it far easier to plan your move to lower-carbon heating with confidence.
BUS and Ofgem: what each one does
BUS stands for the Boiler Upgrade Scheme, a government-backed scheme designed to help eligible households in England and Wales replace fossil-fuel heating with low-carbon alternatives. For most homeowners, this means an air source heat pump. Ground source heat pumps may also qualify, while biomass boilers have more limited eligibility in certain rural locations.
The current grant for an eligible air source or ground source heat pump is £7,500. It is not normally paid into your bank account. Instead, the amount is deducted from the installer’s invoice once the application and installation have been completed correctly. You pay the remaining agreed cost of the project.
Ofgem is the scheme administrator. It oversees voucher applications, checks that the relevant requirements have been met and processes the grant through the installer. Ofgem does not visit your home to design a heating system, recommend a heat pump size or arrange the fitting. Those are the responsibilities of a qualified, scheme-eligible installer.
That distinction matters. A grant voucher is valuable, but it does not make every property or every quote the same. A good installation starts with the home itself: its heat loss, insulation, radiator capacity, hot-water demand and available outdoor space all influence the best solution.
Who may be eligible for the Boiler Upgrade Scheme?
The scheme is intended primarily for existing homes and qualifying non-domestic properties that are replacing fossil-fuel heating, such as a gas boiler, oil boiler, LPG system or direct electric heating. There are specific rules, and eligibility can change, so your installer should confirm the latest position before any commitment is made.
In practical terms, a suitable property will usually need an existing heating system to replace and enough space for the external heat pump unit, hot-water cylinder and associated pipework. Most air source heat pumps need a cylinder because they heat water more gradually than a conventional combi boiler. If your home has a combi boiler with no cylinder, this does not prevent an upgrade, but it does mean the internal layout needs careful consideration.
Your property should also be suitable for an efficient heat pump system. That does not mean every home has to be newly built or perfectly insulated. Many traditional houses can work well with a heat pump after targeted improvements. However, draughts, poor loft insulation, uninsulated walls or undersized radiators can increase running costs and reduce comfort if they are not addressed as part of the wider plan.
A grant is not a guarantee that a heat pump will be free. The £7,500 contribution may cover a substantial proportion of the work, and in some smaller or straightforward projects it can make the cost very manageable. Larger homes, complex pipework, radiator upgrades, cylinder installation, electrical work or insulation improvements can add to the overall price. Clear, itemised pricing is essential so you can see exactly what the grant covers and what you will pay.
The installer applies, not the homeowner
One of the most common misunderstandings is that homeowners apply directly to Ofgem. In most cases, the installer handles the BUS application on your behalf. They will need your permission and accurate property details, then submit the voucher request before installation begins.
Only installers with the appropriate scheme accreditation can submit an application. This is a key protection for homeowners. It helps ensure the system is designed, installed and commissioned to recognised standards, with the paperwork needed for the grant and for future support.
You should not be asked to pay a deposit on the assumption that a voucher will definitely be approved without being given clear information about the process. A professional installer will explain the timing, any conditions attached to the quote and what happens if circumstances change.
Why a property assessment comes before a BUS application
The best heat pump installations are not chosen simply by replacing a boiler with a similar-sized unit. Boilers are often oversized, and heat pumps work differently. They deliver a steady, lower-temperature heat over longer periods, which can create a comfortable and consistent home when the system is designed properly.
A detailed assessment should look at how quickly your home loses heat. This helps calculate the size of heat pump required and identify whether improvements such as loft insulation, cavity wall insulation or upgraded radiators would deliver better results. It should also consider your household routine, including how many people need hot water and when they use it.
For example, a well-insulated three-bedroom home with suitable radiators may be ready for an air source heat pump with modest changes. A larger, older property may need radiator upgrades, insulation work or zoning changes first. Neither route is automatically wrong. The right option depends on the property, budget and the standard of comfort you expect.
This is where choosing one provider able to consider heating, insulation, solar and battery storage can be useful. Rather than treating each improvement in isolation, you can build a staged plan that works for your home. Solar panels and battery storage do not make a heat pump grant application more likely, but they can help reduce the cost of electricity used by the heat pump over time.
What the BUS process usually looks like
Although paperwork sits behind the scheme, the customer journey should be straightforward. It generally follows four practical stages:
- A qualified installer carries out a home assessment, discusses your current boiler, energy use and heating needs, and recommends a suitable system.
- You receive a clear quotation showing the proposed heat pump installation, any additional works and the £7,500 BUS grant where eligibility is expected.
- The installer applies to Ofgem for the voucher before work starts and keeps you informed of the outcome and timescales.
- Once the system is installed, commissioned and the required evidence is submitted, the grant is applied to the project cost and you receive the relevant handover information.
Timescales vary. Voucher processing, equipment availability, weather and the scale of preparatory work can all affect an installation date. Asking for a realistic programme at quotation stage is better than relying on a vague promise of a fast fitting.
Questions to ask before choosing an installer
A heat pump should last for many years, so the decision should not rest on the headline grant alone. Ask whether the installer can explain the proposed heat loss calculation in plain English, what flow temperature the system is designed to run at and whether your existing radiators will be sufficient. You should also understand where the outdoor unit and cylinder will be located, how noise considerations are addressed and what ongoing support is available after commissioning.
It is equally sensible to ask what is included in the price. Does it allow for electrical alterations, condensate drainage, controls, radiator upgrades, removal of the old boiler and making good after pipework changes? Transparent answers help avoid unexpected extras later.
Finance options can make the customer contribution easier to spread, but compare the total repayable amount as well as the monthly figure. The most affordable route is the one that gives you a properly designed system, clear terms and manageable payments – not simply the lowest initial quote.
Make the grant part of a better home energy plan
The Boiler Upgrade Scheme is most useful when it supports a heating system that is right for your home, rather than pushing you into a rushed decision. Ofgem’s role gives the process structure, but an accurate survey and quality installation are what determine how comfortable, efficient and reliable your new heating will be.
If you are considering replacing an old boiler, start by finding out how your home performs now. A practical assessment can show whether a heat pump is ready to install, what improvements would make the biggest difference and how the BUS grant could reduce the cost of moving to cleaner, more dependable heating.