Boiler Upgrade Scheme (£7,500) Explained (2026): Eligibility, Process, and What Your Installer Does.

If you are considering a heat pump in Bristol or the South West, the Boiler Upgrade Scheme (BUS) can reduce the upfront cost by thousands. The problem is that most people only see the headline number and miss the details that decide whether you qualify, what type of system is eligible, and what a competent installer should do before anyone applies for a voucher.

This guide explains BUS in clear, practical steps: what you can get, who qualifies in England and Wales, the difference between air-to-water and air-to-air systems (this catches people out), how the application actually works, and the checklist you should expect from a professional installer. If you want local advice and a site assessment, you can request a free survey with Controlled Climate.

Boiler Upgrade Scheme in 60 seconds

BUS is an upfront grant that helps property owners switch from an existing heating system to a low-carbon alternative. You do not normally apply directly. Instead, you get quotes from MCS-certified installers, agree on a quote, and your chosen installer applies on your behalf. If the application is successful, the value of the grant is deducted from what you pay for the installation.

Before you invest time in quotes, verify the core scheme details on official guidance. The simplest starting point is the GOV.UK eligibility page for the Boiler Upgrade Scheme.

What you can get and what the BUS will not fund

Grant values and eligible technologies

BUS currently provides one grant per property for an air source heat pump, a ground source heat pump (including certain water source and shared ground loop set-ups), or a biomass boiler. The grant values are fixed and are designed to reduce the installation cost rather than cover the whole project.

Common exclusions that matter in real quotes

The fastest way to waste time is to assume “heat pump” means “eligible”. BUS does not fund hybrid heat pump systems (for example, a combination of a gas boiler and an air source heat pump). It also will not fund replacing an existing low-carbon heating system. If a sales proposal mentions “hybrid” or implies the old boiler stays in place as part of the main heating strategy, treat that as a sign you may be outside BUS rules.

Capacity limits and why some properties need extra care

BUS sets capacity limits (including 45kWth for individual systems and a higher limit for shared ground loops). Most homes will never touch these figures, but they can matter for larger properties and some small business buildings. If you are in that category, expect a more technical design and a more detailed quote, not a “template” price.

One grant per property and “already funded” systems

You can only get one BUS grant per property. You also cannot get a grant for a property that has already been given government funding or support for a heat pump or biomass boiler. If you have had previous support for low-carbon heating, your installer should confirm whether it affects eligibility before any application is submitted.

Eligibility rules

Most eligibility questions fall into four buckets: who you are, what property you own, what you are replacing, and whether your paperwork supports the application. This section gives you a practical way to self-check before you invite installers out.

Who can apply

BUS is not limited to “main residences”. The scheme guidance explicitly covers owners of second homes and rental properties (where you own the property). It can also apply to certain business-owned properties, as long as the property category fits the scheme rules. If you are a landlord, treat the install like any other significant building services upgrade: confirm tenant access, plan downtime, and document the outcome.

What you must be replacing (and why wording matters)

BUS eligibility depends on replacing an existing heating system. The official eligibility wording includes examples such as oil, gas, electric or LPG. In practice, you should come to the survey with clarity on what you have now (boiler make/model, fuel type, cylinder presence, and any existing hot water controls) because it speeds up the installer’s eligibility confirmation and design work.

EPC requirements and the May 2024 change

Your property must have a valid Energy Performance Certificate (EPC), and an EPC is valid for 10 years. Ofgem checks the EPC is valid and issued within the last 10 years before approving an application. If you do not have a current EPC, sort this out early because it is one of the most common avoidable delays.

The other EPC-related issue is insulation. For applications properly made after 8 May 2024, there are no minimum insulation requirements. That said, removing an eligibility barrier does not change the physics. Heat pumps typically perform best in well-insulated homes, and most good installers will still discuss reasonable insulation upgrades because it can reduce the required heat pump size and improve comfort.

New builds, self-builds, and social housing.

BUS is not designed as a default “new build heat pump discount”. Most new-build properties are not eligible. New builds still being built by the developer are not eligible. There is a narrow scenario where you move into a finished new build that has a fossil fuel boiler, and you may be able to get a grant for a heat pump under the scheme.

Social housing is not eligible under BUS. Self-build eligibility exists in specific circumstances, but biomass boilers cannot be funded in self-build properties. If you are anywhere near these edge cases, do not rely on assumptions. Get the installer to confirm your eligibility in writing before any application is made.

The heat pump detail many people miss: air-to-water vs air-to-air

“Heat pump” is a broad label. BUS eligibility is not. One of the most important technical rules is that BUS-eligible air source heat pumps must be hydronic (air-to-water). Air-to-air systems are not eligible under BUS.

What “hydronic (air-to-water)” means in a home

A hydronic heat pump heats a liquid (water) that circulates through your emitters, typically radiators or underfloor heating, and usually provides domestic hot water via a cylinder. This is the kind of system people mean when they talk about replacing a gas boiler with a heat pump for whole-home heating.

How to tell what you are being quoted for

If a quote includes a hot water cylinder, flow temperatures, radiator or underfloor compatibility, and pipework changes, it is likely discussing an air-to-water system. If the quote focuses on wall-mounted indoor units, room-by-room heads, and refrigerant pipe runs with no hot water cylinder discussion, it may be describing an air-to-air system (often marketed as “air conditioning with heat pump heating”).

Air-to-air can be a sensible comfort upgrade in some properties, particularly if you want efficient heating and summer cooling, but you should treat it as a different decision. It should not be positioned as BUS-funded, because it is not eligible under the current guidance.

Why this distinction affects cost, disruption, and expectations

The difference is not just paperwork. Air-to-water projects usually involve more enabling works (emitters, cylinder, hydraulics, and controls), but they align with whole-home boiler replacement. Air-to-air projects can be less disruptive in some homes, but they do not directly replace a wet heating system in the same way and are not supported by BUS. Mixing these up leads to the most common “why did my quote change?” conversations.

How the BUS application actually works (step-by-step)

If you understand the sequence, you can spot weak installers early. BUS is structured so that the installer does most of the formal steps, but you still have key responsibilities: confirming consent, providing accurate information, and keeping the project moving within scheme time limits.

Step 1: Speak to suitable MCS-certified installers and get quotes

GOV.UK’s process starts with contacting suitable MCS-certified installers to get quotes. Do not treat “quotes” as a quick phone estimate. For BUS, a credible quote normally follows a survey because the installer must be confident in eligibility, heat loss, system sizing, and the scope of enabling works.

Practical tip: ask each installer whether they have included all enabling works needed for a working system (emitters, cylinder if required, controls integration, electrics, condensate handling). A heat pump quote that only prices the outdoor unit and a cylinder is often incomplete.

Step 2: Confirm eligibility and agree on a quote you can actually sign

The installer should confirm whether you are eligible and then agree a quote with you. Treat this as a checkpoint, not a formality. If you are in a “most new builds are excluded” category, if your EPC is missing or expired, or if you are unsure what you are replacing, this is where the installer should stop and clarify before any application is made.

Step 3: The installer applies on your behalf, and Ofgem verifies consent

Once you agree to a quote, the installer applies it on your behalf. Ofgem emails the property owner to confirm that you consent to the installer making an application on your behalf and to confirm key eligibility details. This is a fraud-prevention step, and you should expect it. If you are told “you won’t hear from Ofgem”, that is a warning sign.

Step 4: Voucher issued, then installation and commissioning within strict time limits

After eligibility checks, Ofgem issues a voucher for the grant amount. From the voucher issue date, Ofgem’s installer guidance explains that installers have 3 months to complete the installation for heat pumps (and 6 months for ground source heat pumps). Separately, GOV.The UK also notes that the installer must commission and install the heat pump within 120 days of applying for the grant. In plain terms: you have a few months, not an open-ended window, so schedule early.

Commissioning is not “switching it on”. In Ofgem’s process description, a system is only commissioned when the whole system (including emitters it will operate with) has been installed and tested in line with MCS standards and manufacturer requirements. The installer then generates the MCS installation certificate.

Step 5: Voucher redemption, MCS paperwork checks, and what you pay

After commissioning and generating the MCS installation certificate, the installer applies to Ofgem to redeem the voucher. Ofgem conducts final eligibility checks, including reviewing details on the MCS installation certificate. From the homeowner’s perspective, the important commercial point is this: GOV.UK states that the value of the grant is taken off the amount you pay for installation. You are generally paying the net cost after the voucher value is applied, not paying everything upfront and “waiting for a reimbursement”.

What your installer does (what “good” looks like)

The installer’s job is not to “fit a box”. A BUS-funded heat pump replacement is a designed heating system. The best outcomes come from good survey work, correct sizing, realistic enabling works, and clear handover. If any of these are missing, comfort and running costs usually suffer.

Survey scope: heat loss, emitters, hot water, siting

A proper survey should cover: room-by-room heat loss (or an equivalent formal assessment), existing radiator and pipework suitability, domestic hot water demand, cylinder space, and a practical outdoor unit location. You should also discuss noise and neighbour considerations at this stage because a last-minute “we can’t put it there” change often forces compromises.

Locally, Controlled Climate’s survey approach is described as measuring the space, assessing heat loads, and reviewing installation routes before recommending a correctly sized, compliant system. If you want that kind of survey-first approach, start here: free survey request form.

Design scope: sizing, flow temperature strategy, controls and zoning

“Right-sized” matters more than many people expect. Too small and your home struggles in colder weather. Too large and you may get cycling, lower efficiency, and unnecessary cost. Design also includes flow temperature strategy (heat pumps are typically most efficient when they can run at lower flow temperatures) and control strategy (how the system responds across zones, schedules, and hot water demand).

There are also scheme standards to meet. Ofgem’s property owner guidance states heat pumps must meet a minimum efficiency requirement, including a seasonal coefficient of performance (SCOP) of at least 2.8. You do not need to become an engineer, but you should expect the installer to choose a compliant model and explain what that means for your system design.

Enabling works: the hidden scope that changes quotes

Enabling works are where “cheap quotes” usually fall apart. Common enabling works include radiator upgrades (or adding emitters), pipework modifications, a correctly sized hot water cylinder, upgrading controls, and sometimes electrical works. A credible quote either includes these items or clearly states what is excluded and what assumptions were made.

Commissioning and handover: what you should receive

Good handover is practical and documented. You should understand: normal operating temperatures, how to run schedules, how hot water reheat works, what to do if the system flags a fault, and what settings not to change. On the paperwork side, GOV.UK’s installer guidance advises that if you use an MCS-certified installer, you should receive an MCS commissioning certificate within 10 days of completion. Keep that document, as it is key if you ever need to query the installation.

Budgeting: what the grant reduces, and what it does not

The BUS grant reduces your upfront installation cost by a fixed amount. Your final out-of-pocket cost depends on the system type and the enabling works your property needs. This is why “£7,500 off” is not the same thing as “£7,500 total”.

Typical cost context (not a quote)

For a realistic starting point, the Energy Saving Trust cites typical installation costs of around £11,000 for an air source heat pump and around £29,000 for a ground source heat pump. Treat these as context only. They are not a promise for your property, and they do not include every possible enabling work scenario.

Why do quotes vary so much?

Heat loss drives heat pump size. Heat pump size drives emitter requirements. Emitter requirements drive how much pipework and room work is needed. Add hot water cylinder changes, electrical supply considerations, and outdoor unit positioning, and you can see why “two similar houses” can still receive very different quotes.

Payments, deposits, and keeping the voucher timeline safe

Because the grant is administered through the installer, you should expect an invoice structure that reflects the net cost after the voucher value is applied (as described on GOV.UK). You may still be asked for a deposit or staged payments, especially if equipment must be ordered in advance. The key is to ensure timelines are aligned: voucher deadlines, equipment lead times, and any enabling work by other trades should be planned before the voucher clock becomes the limiting factor.

Running costs: what genuinely influences them

Be sceptical of simplistic savings promises. Running costs are shaped by your home’s heat loss, the temperatures the system needs to deliver comfort, how your hot water demand is managed, and your electricity tariff. The best “running cost reduction” steps are usually design and fabric-led: correct sizing, sensible controls, and practical insulation improvements where they make sense for your building.

Common pitfalls, red flags, and how to protect yourself

Red flag 1: confusion (or silence) on air-to-water vs air-to-air

If an installer cannot clearly explain whether you are being quoted for a hydronic air-to-water heat pump (eligible) or an air-to-air system (not eligible), stop the process. This is the most common route to wasted surveys and mismatched quotes.

Red flag 2: “grant guaranteed” language or pressure selling

Eligibility depends on your property and what you are replacing. It also depends on correct documentation and compliant commissioning within the scheme timelines. Any business that frames BUS as “automatic money off” without verifying your case is not acting in your interests.

Red flag 3: no heat loss work and vague scope

A heat pump is a designed system. If the quote does not reflect survey work, emitter requirements, and controls, you are likely looking at an incomplete scope that will reappear later as “extras”.

Red flag 4: timeline risk treated as an afterthought

Voucher deadlines are real. If the installer’s programme is vague, if equipment lead time is not discussed, or if they cannot explain commissioning and documentation steps, you risk a stressful project and avoidable delays.

Practical next steps for Bristol and the South West

If you want to move forward responsibly, aim for a simple sequence: confirm your EPC, confirm what you are replacing, get surveyed quotes from suitable installers, and only then proceed to the application steps.

Pre-survey checklist (bring this to your first appointment)

• Your EPC (or confirmation you have booked one if it is missing or expired)
• Photos of your boiler area, hot water cylinder (if present), and consumer unit location
• Basic heating information: radiator types, any underfloor heating, and any known cold rooms
• Outdoor constraints: likely outdoor unit locations and any neighbour-sensitive boundaries
• Confirmation of what you are replacing (fuel type and system type)

Questions to ask any installer before you sign

• Are you quoting an air-to-water system (hydronic), and how will hot water be provided?
• What heat loss assessment will you carry out, and what assumptions are you making?
• What enabling works are included (emitters, cylinder, controls, electrics), and what is excluded?
• How will you manage voucher timelines, commissioning, and MCS documentation?
• What aftercare and servicing support is available once the system is live?

Local help: survey-first guidance without guesswork

If you are based near Bristol and want a site assessment that covers heat loads, routes, and practical constraints before you commit, Controlled Climate offers a survey-first approach and states it has delivered air conditioning and heat pump solutions for more than 30 years. You can review the company background here: About Controlled Climate.

When you are ready to discuss your project, use the contact page so you can confirm whether BUS is appropriate for your property and what the most sensible next step is.

Summary

The Boiler Upgrade Scheme can reduce upfront costs, but success depends on details: correct eligibility (ownership, EPC, replacement system), choosing the right system type (BUS air source heat pumps must be hydronic air-to-water), and working with an installer who surveys properly, sizes correctly, and manages voucher timelines and MCS paperwork. If you treat BUS as a structured project rather than a discount code, you dramatically reduce risk and improve the odds of a comfortable, efficient installation.

Frequently Asked Questions

Can I apply for the Boiler Upgrade Scheme myself?

In most cases, no. The normal process is that you obtain quotes, agree on a quote with your chosen installer, and the installer applies on your behalf. You should still expect Ofgem to contact you to confirm consent and eligibility details.

Do I still need loft or cavity wall insulation to qualify?

For applications properly made after 8 May 2024, there are no minimum insulation requirements. However, heat pumps typically perform best in well-insulated homes, so good installers still discuss sensible energy efficiency improvements.

Are air-to-air heat pumps eligible for the £7,500 grant?

No. BUS-eligible air source heat pumps must be hydronic (air-to-water). Air-to-air systems are not eligible. If you are being quoted for wall-mounted indoor units with no wet heating integration, clarify this before proceeding.

Can landlords apply for BUS on rented properties?

The eligibility guidance includes owners of properties you rent out to tenants. You still need a valid EPC and must meet the replacement and property eligibility rules. Plan tenant access and downtime carefully.

Is my new build eligible?

Most new-build properties are not eligible, and properties still being built by the developer are not eligible. There is a limited scenario where a finished new build with a fossil fuel boiler may be eligible. Treat this as a confirm-before-you-commit point.

What counts as a valid EPC for BUS?

Your property must have a valid EPC. An EPC is valid for 10 years. Ofgem checks the EPC is valid and issued within the last 10 years before approving applications.

How long does the installation process take once a voucher is issued?

Voucher-related timelines are strict. Ofgem’s installer guidance describes a 3-month completion window for heat pumps from voucher issue (and 6 months for ground source). GOV.UK also references commissioning and installation within 120 days of applying. Ask your installer to confirm the schedule they will work to.

What paperwork should I expect after installation?

You should receive clear commissioning and handover information. If you used an MCS-certified installer, you should receive the MCS commissioning certificate within 10 days of completion. Keep all documents, warranties, and settings guidance for future servicing and support.