AI Voice for Heat Pump Installers: BUS Voucher Calls

A heat pump enquiry used to be a sales call. Under the Boiler Upgrade Scheme it has become the first step in a regulated sequence with three clocks running inside it: the property owner's window to confirm consent with Ofgem, the voucher's validity window, and the commissioning rule that ties an installation date to the application date. Demand moving through that sequence is rising quickly. To the end of August 2026, installers had submitted 151,136 voucher applications, and August 2026 was the second highest month for applications since the scheme began, according to the DESNZ Boiler Upgrade Scheme statistics for August 2026.

This guide is written for the Head of Customer Operations, or the COO, at an MCS-certified installer in England or Wales. It covers the calls that the scheme itself creates: the enquiry that must carry the grant as an upfront discount, the owner who has a fortnight to answer Ofgem, and the installation that has to land inside the voucher window. It deliberately cedes two neighbouring questions. Generic enquiry triage, meaning which questions qualify a caller before a survey, is covered in our guide to AI voice for EV charger installers. Diary scheduling across a mixed boiler and heat pump workload, with the Gas Safe boundary, belongs to our guide to boiler service booking.

This guide is shipped by the team behind Dilr Voice, a multi-agent voice AI platform that runs inbound front desk calls and outbound campaigns with full audit trails on every call. Or see DATS, our five-stage method for placing AI inside a business.

Why does the Boiler Upgrade Scheme turn an installer's phone line into a deadline system?

The Boiler Upgrade Scheme is installer-led, so the installer applies for the grant, Ofgem then asks the property owner to confirm consent, and the installation must be finished inside the voucher's validity window. Most of those stages depend on a phone conversation landing on time. For a heat pump installer, a missed or late call is no longer just a lost lead; it can mean a rejected application or an expired voucher.

The volumes explain why this has become an operations problem rather than a sales one. The DESNZ release counts 125,321 vouchers issued and 93,364 redemptions paid to the end of August 2026. August 2026 was the highest month on record for vouchers issued, at 5,903, and for redemptions paid, at 3,260. Applications that month were 7,486, which is 120% higher than August 2025, and only July 2026 was busier, at 8,150. Of the August vouchers, 43% were for the new uplifted grant for off-gas grid homes, a route that only opened in July.

Read that pipeline from the installer's side. Every application above the voucher line is either waiting on the owner's confirmation or Ofgem's checks, or has been rejected. Every live voucher above the redemption line is an installation that, unless it is cancelled, has to be fitted, commissioned and claimed before the voucher runs out. Of the 93,364 installations already paid, 55% replaced a gas system and 17% replaced oil, so most completed households switched away from gas or oil, and a household making that switch for the first time will reasonably have questions. Much of the resulting phone traffic sits inside one of the scheme's time limits. The same pattern of demand outrunning a contact line appears in our wider look at where AI pays for UK utilities, from the supplier side of the meter.

How does the voucher sequence work, and where does each call sit?

The Boiler Upgrade Scheme normally runs in this order. The installer surveys and quotes, then submits a voucher application on the owner's behalf. Ofgem contacts the owner to confirm consent and eligibility, issues the voucher once both are in, and the installer then fits, commissions and claims the grant. An installer's calls cluster around three of those handoffs, so a voice agent is placed at those handoffs rather than spread across everything.

Ofgem sets out the consent step on its Boiler Upgrade Scheme page for property owners, and the wording matters for anyone designing the calls around it: "If we do not receive your confirmations of the above within 14 calendar days, we may reject the application." The "we" is Ofgem. The duty to respond sits with the owner, and the decision sits with the regulator; the installer sits between them and depends on both.

Three of those five stages generate calls an installer can plan for. The enquiry produces inbound volume. The consent window produces outbound reminders and inbound questions from owners who have received something from Ofgem and are unsure what it means. The voucher window produces scheduling calls, reschedules and the occasional cancellation. The application itself is paperwork between the installer and Ofgem, and no voice agent belongs in it. Redemption is mostly paperwork too, with one exception covered below: a short call to confirm the commissioning date. Getting that split right is the same placement question we work through in an AI placement diagnostic: which steps carry the volume, and which steps carry the judgement.

What should an AI voice agent say about the grant on the first call?

An AI voice agent on a heat pump installer's line should state the published Boiler Upgrade Scheme grant values, explain that the installer applies on the owner's behalf, and explain that any grant is shown as a discount on the quote. It should record what the caller says about fuel, property and gas connection, then book a survey. It must never tell a caller they qualify, because Ofgem decides that.

The rules here bind the installer, not the caller, and they shape the script, which is why our approach to placing AI starts from the rule set rather than the technology. Ofgem's scheme page for installers says installers must pass on the full value of the grant as an upfront discount, and that the discount must appear at the quote stage and on the invoice. An agent that talks about "getting the grant back later" is describing a model the scheme does not allow. The published values on Ofgem's Boiler Upgrade Scheme page are 7,500 pounds for air-to-water and ground source heat pumps, 2,500 pounds for residential air-to-air heat pumps, 5,000 pounds for biomass boilers, and 9,000 pounds for air-to-water or ground source heat pumps in eligible off-gas grid properties, with that uplift available until 31 March 2027. Only the uplift carries that end date; DESNZ reports that scheme funding is confirmed to 2029/30 through the Warm Homes Plan.

The off-gas uplift is where a script most easily over-promises. To qualify, a property must not be fuelled by mains gas, and Ofgem's guidance is explicit that a capped or clamped supply meter point still counts as mains gas. The heating system being replaced must run on oil or LPG. A caller who says "we've had the gas capped" sounds like an uplift case and is not one. So the agent records statements, never conclusions: the caller said the current system runs on oil; the caller said there is no gas meter; the caller said the property has an Energy Performance Certificate. The surveyor and Ofgem draw the conclusion. The same discipline is built into how Dilr Voice is configured, where per-call audit trails let a team check exactly what was said and recorded.

The phrases that must never appear in the agent's output are the obvious ones: anything telling a caller they qualify, are eligible, or will receive the full grant. A voice agent can quote a published number and attribute it to Ofgem. It cannot attach that number to a specific household. That boundary is cheap to build and expensive to miss, because a promise made on the installer's line is the installer's promise, whatever Ofgem later decides.

How should a voice agent handle the owner's 14-day consent window?

During the Boiler Upgrade Scheme consent window, a voice agent should run neutral reminder calls telling the owner that Ofgem will contact them and that the application needs their confirmation. It should answer questions about what consent means and offer a human for anything else. It must never confirm consent on the owner's behalf, and never suggest that confirming commits the owner to the installer.

Two details on the Ofgem owners page change how those calls should be written. First, confirming consent does not commit the owner to a particular installer; Ofgem says that is a separate contractual matter. Second, where more than one installer has applied for the same property, the owner can confirm consent to only one, and Ofgem rejects the others. In a market where households collect several quotes, which Ofgem itself recommends, a fortnight of silence from an owner may mean they have confirmed another installer's application. A reminder call that asks whether the owner has heard from Ofgem, and whether they still want to proceed, surfaces that early. A call that pressures them to confirm crosses a line.

That line is also a legal one for the caller. The ICO's guidance on direct marketing and regulatory communications defines service messages as messages sent for purely administrative or customer service purposes that carry no promotion or advertising, and treats a message that is neutral in tone as unlikely to be direct marketing. A factual reminder about a pending application fits that description. A reminder that also pushes an upgrade, a battery or a finance offer does not, and an automated call made for direct marketing purposes needs prior consent under regulation 19 of PECR. Regulation 19 is framed around the person who transmits or instigates the call, which in this case is the installer running the campaign; the installer cannot treat that duty as the voice platform's problem. The fuller treatment of consent, calling hours and the TPS sits in our guide to AI outbound calling under GDPR and PECR.

In practice the reminder flow is short. Day two after the application, a call confirms the owner knows Ofgem will be in touch and checks the contact details on file. Around day seven, a second call asks whether Ofgem's message has arrived and whether the owner has any questions. Anything about the contract, the price or a competing quote goes to a person through a warm transfer with the context attached, which is the handover pattern we cover in warm transfer and context handoff. The agent logs each attempt and outcome, so the installer's team can see which applications are at risk before day fourteen rather than after.

How does a voice agent keep installations inside the voucher window?

A Boiler Upgrade Scheme voucher for an air-to-water or air-to-air heat pump is valid for three months from approval, and six months for a ground source heat pump. A voice agent keeps installations inside that window by running outbound scheduling campaigns from a list of issued vouchers, retrying unanswered calls within set hours, and passing every outcome back so a human planner can see which jobs are running short of time.

The consequence of missing the window is set out on the Ofgem owners page: if the installer does not complete the work within the time limit, it must submit a new application, and the owner must confirm consent again. That means a fresh application for Ofgem to process, another consent confirmation from the owner, and a second chance for the household to reconsider. For an installer, an expired voucher is rework on both sides of the relationship.

The scheduling problem is ordinary, but the deadline makes it unforgiving. An outbound campaign built on an uploaded list of issued vouchers can call each owner to agree an installation date, with scheduling windows set to the hours the office wants, retry logic for unanswered calls, and an automatic pause at the configured end of the day. Every outcome, whether a date agreed, a callback requested or a refusal, writes back to the CRM, so the planner can see which owners have agreed a date and which have not, rather than relying on memory. Platforms built for this kind of outbound work, Dilr Voice among them, record sentiment and outcomes in real time, which shows which households are hesitating while there is still time to act.

The third clock runs the other way. Ofgem's installer guidance says the new heat pump must be commissioned no more than 120 days before the voucher application is properly made. That matters for an installer that fits first and applies afterwards, an approach the scheme permits within that limit. A post-installation call that confirms the commissioning date and prompts the office to file promptly protects that route. None of this replaces the planner's judgement on sequencing; it removes the chasing that consumes it. The same diagnostic logic underpins our AI execution office, which runs the operational follow-through once a system like this is live.

Which numbers should a heat pump installer measure on these calls?

A heat pump installer should measure Boiler Upgrade Scheme calls by their effect on the voucher sequence rather than by call volume alone. The useful measures are the share of applications confirmed by owners within 14 days, the number of days from voucher issue to installation, the count of vouchers that expire, and how quickly enquiries are answered. These link the phone line directly to grant income and installation dates.

Each measure maps to a call type. Consent confirmation rate is the outcome of the reminder flow. Days from voucher to install is the outcome of the scheduling campaign. Expired vouchers are the failure the whole system exists to prevent, and each one is worth a short review of where the calls broke down. Speed to answer on inbound enquiries matters because households collect several quotes, so an unanswered call can easily go to the next installer a household finds through the MCS website.

These measures are ours, not the scheme's, and they are only useful if the call records are clean enough to compute them. That is a design choice made at the start, not an analytics project later. Our ROI framework for AI voice sets out how to turn measures like these into a business case, and our AI operating model work covers who owns each number once the calls are running. For the wider picture of how voice agents are deployed across sectors, the enterprise guide to AI voice agents is the place to start.

What is the best AI voice setup for a heat pump installer in 2026?

The best AI voice setup for a heat pump installer in 2026 is one that handles three Boiler Upgrade Scheme call types well: inbound enquiries with grant-as-discount scripting, neutral consent reminders, and voucher-window scheduling, all with a call record the office can audit. The right choice depends on volume, in-house technical skill and how much of the voucher sequence the installer wants automated.

Four criteria separate the options. First, scope control: can the agent be kept from telling a caller they qualify, and can that be tested before it goes live? Second, outbound discipline: does it support scheduling windows, retries and an end-of-day pause, so reminder calls stay neutral and on time? Third, records: does every call leave a record and outcome the planner and a compliance reviewer can read? Fourth, handover: can a human take over mid-call with the context intact? We set out how we compare platforms against criteria like these in our best AI voice agent guide for 2026.

There are scenarios where another route wins, and an installer should take them seriously. A small installer fitting a handful of systems a month, with an office manager who answers every call, may be better served by a person and a shared calendar than by any AI. An installer with an in-house developer who wants full control may prefer to assemble its own agent on Vapi, Retell AI or Synthflow, accepting the build and maintenance work that comes with it; we compare those trade-offs in build versus orchestrate versus buy. A national installer with a large contact centre may look at enterprise conversational platforms such as PolyAI. A managed platform earns its place for the regional installer in between, with volume high enough that missed calls cost vouchers and no appetite to run a voice stack. Our orchestration versus platform comparison goes further into that choice.

Can an AI voice agent confirm consent to Ofgem on the owner's behalf?

No. Under the Boiler Upgrade Scheme, Ofgem contacts the property owner directly, and the owner confirms both consent and eligibility. A voice agent working for the installer can remind the owner that Ofgem will be in touch, explain what confirming means, and answer questions. It cannot confirm on the owner's behalf, and an installer should never design a call that tries to.

What happens if two installers apply for the same property?

Under the Boiler Upgrade Scheme, the property owner can confirm consent to only one installer's application, and Ofgem then rejects any others for that property. For an installer, a quiet owner during the 14-day window may have chosen a competitor. A neutral reminder call that asks whether the owner still wants to proceed is the fastest honest way to find out.

Does the Boiler Upgrade Scheme cover the whole of the UK?

No. Ofgem states that the Boiler Upgrade Scheme is open in England and Wales, and the governing legislation is titled the Boiler Upgrade Scheme (England and Wales) Regulations 2022. An installer working across borders needs its voice agent to recognise the property's location early in the call, so it does not describe grants that do not apply. This guide does not cover schemes in Scotland or Northern Ireland.

The regulations themselves are on legislation.gov.uk, and Ofgem's guidance pages carry the operational detail an installer's scripts should be checked against. For how voice AI fits regulated work more broadly, see our guide to AI voice compliance in the UK and EU, the AI voice by industry overview, and the rest of our voice AI writing.

Want to see this in production? Try Dilr Voice live, compare options in our voice AI buyer's guide, see our DATS methodology, or read about our approach to placing AI inside operational teams.

Written by the Dilr.ai engineering team, practitioners who ship enterprise AI in production. Follow us on LinkedIn for shipping notes, or subscribe via the RSS feed.