What Happens After You Apply for the Boiler Upgrade Scheme? A Step-by-Step Guide

Once your MCS certified installer submits your Boiler Upgrade Scheme application, Ofgem typically issues a voucher within 2 to 3 working days. From there, your installer has 120 days (about 4 months) to complete the heat pump installation and redeem the voucher. The whole process from application to a working heat pump usually takes between 4 and 12 weeks, depending on equipment availability and your installer's schedule.

Who Actually Submits the Boiler Upgrade Scheme Application?

This catches a lot of people off guard. You don't submit the application yourself. Your MCS certified installer does it on your behalf through Ofgem's online portal.

Before they hit submit, your installer needs a few things in place. They'll need your property's EPC (Energy Performance Certificate), proof that the property doesn't already have a heat pump, and confirmation that you consent to the application. They also need to confirm the quote, including the agreed price with the £7,500 grant already deducted.

Your job at this stage is pretty simple: make sure your EPC is valid, sign the consent form your installer provides, and check that the quoted price looks right. If your EPC has expired or your home has never had one, you'll need to arrange a new assessment before the application can go in. That typically costs between £60 and £120.

What Does Ofgem Do After the Application Is Submitted?

Ofgem runs a series of automated and manual checks on every BUS application. They're verifying that the property is eligible, that the installer holds a valid MCS certification, and that no other BUS voucher has been issued for your address.

In most cases, this takes 2 to 3 working days. Ofgem themselves state that straightforward applications are processed quickly, but if something flags up during their checks, it can take longer. We've heard of cases dragging on for 2 to 3 weeks when there's a data mismatch on the EPC register.

Once Ofgem is satisfied, they issue a voucher to your installer. You should receive an email confirmation too. Keep that email safe because it contains your voucher reference number and the expiry date.

Common Reasons Your BUS Application Gets Delayed or Rejected

Rejections aren't common, but they do happen. And delays are more frequent than most people expect. Here are the main reasons things get held up:

EPC issues are the single biggest cause of delays. If your property's EPC shows an expired certificate, or if the address on the EPC doesn't exactly match the address on your application, Ofgem will pause everything until it's resolved. Even something as minor as "Flat 2" versus "Flat 2a" can trigger a flag.

Previous grant claims will stop an application dead. If someone already claimed a BUS voucher for your property, even if the installation never happened, you'll need Ofgem to investigate and clear the record. This can take weeks.

Installer certification lapses are rare but they do occur. If your installer's MCS certification expires between submitting the application and Ofgem processing it, the application gets rejected. Always check your installer's certification is current before you commit.

Other reasons include the property not being in England or Wales (Scotland has its own scheme), the home already having a heat pump installed, or the heat pump model not being on the MCS approved product list.

What Happens Between Getting the Voucher and Installation Day?

This is the bit where patience comes in. Your installer has received the voucher and now needs to schedule your installation. Several things happen during this window.

First, your installer orders the heat pump unit and any associated equipment like a hot water cylinder, buffer tank, or new radiators. Supply chain issues have eased since the early days of the scheme, but popular models from manufacturers like Vaillant, Samsung, and Daikin can still have lead times of 2 to 6 weeks.

Your installer may also need to arrange scaffolding, apply for any electrical upgrades with your DNO (Distribution Network Operator), or coordinate with a separate electrician if a new circuit is needed. If your home needs a consumer unit upgrade to handle the heat pump's electrical load, that adds another step.

Here's a real example. A homeowner in Oxfordshire applied through the BUS in early 2026. Ofgem issued the voucher within 3 days. But the Vaillant Arotherm Plus unit they'd chosen had a 4-week lead time, and the DNO needed 3 weeks to approve an electrical supply upgrade. Total time from application to installation: 9 weeks. That's fairly typical.

During this waiting period, don't just sit back. Check that your installer has given you a written installation date. Ask whether they've ordered the equipment. And confirm whether any electrical or building work needs doing before the main install.

How the £7,500 BUS Grant Payment Actually Works

This is where people get confused, so let's be clear. You never see the £7,500 in your bank account. The grant goes directly from Ofgem to your installer after the installation is complete and the voucher is redeemed.

Here's how it works in practice. Say your heat pump installation costs £12,000 in total. Your installer deducts the £7,500 grant upfront, so you pay £4,500. Your installer then completes the work, commissions the system, and submits the redemption paperwork to Ofgem. Ofgem pays the installer the £7,500, usually within 30 days of redemption.

What does this mean for you? You pay only your share, either upfront or according to whatever payment terms you've agreed with your installer. Some installers ask for a deposit when you sign the contract and the balance on completion. Others want full payment on completion day. Clarify this before work starts.

The voucher is valid for 120 days from the date of issue. If your installer doesn't complete and redeem within that window, the voucher expires and you'd need to reapply. This rarely happens, but keep an eye on the timeline, especially if there are delays with equipment or electrical work.

What If My BUS Application Is Rejected? Can I Reapply?

Yes, you can reapply. A rejection isn't the end of the road. But you need to fix whatever caused the rejection first.

If it was an EPC problem, get a new EPC done and make sure the address matches exactly. If the issue was with your installer's certification, you might need to find a different MCS certified installer. And if Ofgem flagged a previous voucher on your property, you'll need to contact them directly to get it cleared. Their contact details are on the Ofgem BUS portal.

Frankly, most rejections are avoidable. A good installer will check everything before submitting. They'll verify your EPC, confirm your property's eligibility, and make sure all the details match. If your installer rushed the application without doing these checks, that should tell you something about how they'll handle the installation itself.

One thing worth knowing: there's no limit on how many times you can reapply, but only one voucher can be active for a property at any time. So if you switch installers mid-process, the old voucher needs to be cancelled before a new one can be issued.

Frequently Asked Questions

How long does it take to get a BUS voucher after applying?

Ofgem typically processes applications within 2 to 3 working days. If there's a problem with your EPC or property records, it can take 2 to 3 weeks. Your installer should let you know as soon as the voucher is issued.

Can I change my installer after the BUS voucher has been issued?

Yes, but the existing voucher needs to be cancelled first. Your new installer then submits a fresh application. This resets the clock, so you'll wait for a new voucher and get a new 120-day redemption window.

What happens if the heat pump installation isn't finished before the voucher expires?

If the 120-day voucher period runs out before your installation is complete and redeemed, the voucher becomes void. You can reapply, but there's no guarantee of approval if scheme funding has been fully allocated. Keep pressure on your installer to stick to the agreed schedule.

Do I have to pay my installer before they get the BUS grant money?

In most cases, yes. You pay your share of the cost (the total minus £7,500) directly to your installer. The installer then claims the £7,500 from Ofgem after completing the work. Your installer carries the risk of the Ofgem payment, not you.

Will Ofgem contact me during the BUS application process?

Ofgem sends you an email when the voucher is issued and may contact you to confirm consent. They can also reach out if there's a problem with the application. Make sure the email address on your application is one you check regularly.

If you're ready to take the next step, or you haven't found an installer yet, use our directory at heatpumpinstallerdirectory.co.uk to find MCS certified heat pump installers in your area. Every installer listed holds current MCS certification, which is the only way to access the £7,500 BUS grant. Get quotes from two or three local installers so you can compare prices, timelines, and the equipment they recommend.