The HIES Consumer Code and Its Deposit and Guarantee Protection

The HIES Consumer Code is one of the two consumer codes approved for renewable and energy efficiency work in the UK, and it is the code that sits behind a large share of Boiler Upgrade Scheme installations. Membership is not optional decoration: Ofgem's scheme guidance states that installers working with consumers must be MCS certified and members of a consumer code approved by the Secretary of State¹. For a household, that means the code is the layer of protection that applies after the installer has been chosen and before, during and after the work.

The protection attached to membership is deposit protection of £5,000 for two years, together with a workmanship warranty and access to an independent dispute resolution route. Those figures are the ones a household should hold on to when comparing quotes, because they set the ceiling on what a code can recover if a member stops trading or refuses to put work right.

This page explains what the code covers, which technologies fall inside it, how a complaint escalates, and where the cover stops. It also sets out the limits plainly: a consumer code is not an insurer, not a regulator and not a guarantee that a company will still be trading when a problem appears.

What the HIES Consumer Code is

HIES is a consumer code, which is a different thing from a certification scheme. Certification bodies such as the Microgeneration Certification Scheme certify that an installer and an installation meet technical standards. A consumer code governs the commercial relationship: how a product is sold, what a contract must contain, how a deposit is handled, what happens when something goes wrong. Ofgem's Boiler Upgrade Scheme guidance for property owners is explicit that there are two consumer codes relevant to the scheme, and HIES is one of them¹.

The code's authority comes from approval rather than from statute. Installers working with consumers must be MCS certified and members of a consumer code approved by the Secretary of State, and that requirement is repeated across the scheme guidance for both property owners and installers¹. The Boiler Upgrade Scheme guidance for installers states the same condition in slightly different words: installers must also be members of an approved code of practice for consumer protection⁵. The most recent installer guidance confirms that installers not yet transitioned to the redeveloped MCS installer scheme must still hold consumer code membership with one of the other two approved codes of practice, HIES and RECC⁶.

That dual structure matters to a household because it means two separate checks are needed. An MCS certificate tells you the technology was installed to a recognised standard. Consumer code membership tells you there is a route to redress if the selling or the aftercare goes wrong. Ofgem's guidance for property owners also notes that the consumer code contact routes for HIES and RECC have been added in a more concise format, which reflects how central the codes are to the complaint path⁷.

The code is not a government body and does not have statutory powers. It is a membership organisation that sets standards its members agree to meet, and it can require remediation or expel a member. That is the source of both its usefulness and its limits.

CTSI approval: one of only two approved codes in renewables

Approval for a consumer code in this sector comes through the Chartered Trading Standards Institute's Consumer Codes Approval Scheme. The Renewable Energy Consumer Code, the other approved code, is described in the scheme's own listing as setting out the standards applicable to the selling or leasing of small-scale heat and power generators, whether from renewable or other low carbon sources, to domestic consumers⁸. HIES sits alongside it under the same approval framework.

The practical consequence of approval is that membership satisfies the condition written into grant scheme rules. The Boiler Upgrade Scheme guidance for property owners states that all BUS installations must be carried out by MCS certified installers who are members of a consumer code approved by the Secretary of State⁹. The installer guidance repeats the requirement, and the redeveloped MCS installer scheme guidance confirms that installers must continue to hold membership with one of the two approved consumer codes, RECC or HIES, until further notice, for work under the Boiler Upgrade Scheme⁵.

There is a wider point about why approval is channelled through Trading Standards rather than through the energy regulator. MCS installation companies working with domestic customers must also be a member of a Consumer Code approved by the Trading Standards Institute². That single sentence links the technical certification scheme, the consumer code and the trading standards framework into one chain, and it is the chain a household is relying on when it accepts a quote from an MCS certified firm.

The approval is not permanent in principle, and codes are expected to maintain their standards to keep it. For a household, the useful takeaway is that HIES membership is not a marketing badge invented by the installer. It is a condition of taking part in the grant schemes that fund much of this work.

What the code covers: solar PV, batteries, EV charge points and heat pumps

The technologies inside the consumer code framework overlap heavily with the technologies covered by certification and by load control rules. The Microgeneration Certification Scheme certifies, quality assures and provides consumer protection for microgeneration installations and installers including solar photovoltaic panels, biomass, wind, heat pumps and heat products¹⁰. That is the certification side. The consumer code side covers the selling of those same systems to domestic consumers.

The load control licence conditions give a more granular list of the devices that fall inside the regulated perimeter: privately owned electric vehicles, electric vehicle smart charge points other than public and rapid charge points, relevant heat pumps, storage heaters, relevant heat batteries, hot water heat pumps, standalone direct electric hot water cylinders, hybrid heat pumps, smart battery energy storage systems, and where appropriate ancillary devices such as smart switches¹¹. That list is drawn from Ofgem's load control consumer protection guidance, and it shows how far the domestic energy device market now reaches beyond a boiler and a cylinder.

Batteries have moved into grant funded work as well. Domestic batteries installed to be used alongside solar PV panels were included as an eligible measure for installation under the Warm Homes: Social Housing Fund in June 2025¹². That is a scheme fact rather than a consumer code fact, but it illustrates the direction of travel: storage is now treated as part of a domestic energy installation rather than an accessory.

For a household, the coverage question is best answered by asking what is being sold and how. If a company is selling a solar PV system, a battery, a heat pump or a home charge point to a domestic customer, and it holds HIES membership, the code's selling standards and its complaint route apply to that transaction. If the same company is selling a product that falls outside the code's scope, membership does not automatically extend to it.

Deposit protection: £5,000 for two years

Deposit protection is the part of HIES membership that most directly addresses the risk a household carries before any work starts. The figure attached to the code is £5,000, covering a two year period¹. That is the amount a member's deposit protection is built around, and it is the number to compare against the size of any advance payment being requested.

The reason deposit protection exists is that energy installations are commonly paid for in stages. A deposit is taken before materials are ordered, a further payment may fall due at first fix, and the balance on completion. If the company stops trading between those stages, the household is exposed. Deposit protection is designed to sit behind that exposure, up to its limit.

It is worth being precise about what a limit means. A £5,000 protection figure is not a promise that any deposit up to £5,000 will be returned in every circumstance. It is the ceiling of the protection attached to membership, and the conditions of the scheme determine when it responds. Households weighing a large advance payment should read the scheme's own terms rather than assume the headline figure applies automatically.

There is a separate statutory protection that can sit alongside a code's deposit protection. Under section 75 of the Consumer Credit Act 1974, credit card purchases costing more than £100 but less than £30,000 carry rights against the card issuer¹³. That is a different mechanism from a consumer code, and it depends on how the payment was made rather than on who the installer is. The two can be relevant to the same job.

Warranty and workmanship protection under the code

Workmanship protection is the second half of what membership provides, and it addresses a different risk from deposit protection. Deposit protection responds to money paid before work is done. Workmanship protection responds to work that was done badly or not completed to the standard the contract required.

The code's workmanship cover is what gives a household a route when an installer disputes whether a fault is theirs. Without it, the fallback is the general consumer law framework, which is slower and depends on the household pursuing the company directly. The Trading Standards Wales guidance on remedies and redress sets out the general position on consumer rights, which applies regardless of whether an installer belongs to a code¹³.

Workmanship cover is not the same as a manufacturer's warranty on the equipment. A boiler, a heat pump or an inverter carries a manufacturer's warranty that covers defects in the product. The workmanship warranty covers the installation: the pipework, the wiring, the commissioning, the roof fixing, the settings. A household can find itself holding a valid product warranty and no remedy for a poor installation, which is exactly the gap the code's workmanship protection is meant to close.

The product safety framework is a third, separate layer. The UK's new product safety framework consultation notes that businesses and other organisations who purchase products for their own use, such as products for use in the workplace, will also receive protection¹⁴. That is about product safety rather than installation quality, but it shows how many distinct regimes can bear on a single domestic energy installation.

For a household, the practical question is what documentation exists at handover. A workmanship warranty is only as good as the record that identifies the installation, the date and the scope. The pages on workmanship warranties and aftercare and on insurance backed guarantees set out what those documents should contain.

How the dispute resolution process works

The complaint route under a consumer code follows a fixed sequence, and the sequence is the same in shape across the energy sector. The first step is always the company. Ofgem's guidance on who to contact states that a complainant should have given the installer at least 10 working days to resolve the matter before contacting the consumer code². That is the gate into the code's own process.

Once the code is involved, the case is handled through the scheme's dispute resolution arrangements. The Energy Ombudsman operates the dispute resolution platform where consumers and suppliers interact with case handlers to resolve service disputes across the energy and communications sector¹⁵. The Facilitated Complaints Resolution service covers disputes against a participating energy supplier, energy broker or heat network, for residential or business consumers¹⁶.

The periods that apply at each stage are set out in the official guidance and they are consistent. Domestic energy suppliers have 8 weeks to investigate and resolve a problem¹⁷. Heat network suppliers have 8 weeks to resolve a complaint¹⁸. The Energy Ombudsman states that a supplier has 8 weeks to resolve the issue unless they send a deadlock letter allowing the consumer to come to the Ombudsman sooner³. For Feed-in Tariff generators, if a mutually agreeable outcome has not been reached after 8 weeks, the case can be referred, and the FIT licensee then has up to 28 days to action any recommendations²⁰.

The pattern is deliberate. Each stage gives the company a defined window to put things right before an independent body becomes involved, and each stage has a documented trigger for moving on. A household that keeps a dated record of when it first raised the issue will always be able to show whether the window has expired.

When the Dispute Resolution Ombudsman can and cannot help

The Energy Ombudsman's remit is broad but bounded, and the boundaries matter more than the breadth. Since 1 April 2025 the Energy Ombudsman can help consumers and small businesses resolve heat network disputes⁴. Heat network consumers can access a free and independent dispute resolution service through it²¹. The service is free to the consumer, which is a material difference from litigation.

The limits are stated plainly by the Ombudsman itself. It cannot punish companies, dictate how companies operate, or issue fines³. That is a significant constraint. A household expecting a penalty to be imposed on a bad installer will not get one from this route. What the Ombudsman can do is review the dispute and make a recommendation, and the company is expected to act on it.

There are also eligibility limits. The Ombudsman is unable to consider disputes from business consumers who do not meet the microbusiness definition²¹. A case acceptance dispute will be rejected if it focuses solely on the type of remedy requested by the consumer²². And the scheme does not cover a consumer who has never been a consumer of the supplier, or a complaint about something outside the scheme's scope, which deals with gas and electricity supply disputes with some ancillary services not covered³.

The Ombudsman can review disputes with any heat network if the heat network supplier has not done what is required of them by the Energy Bill Relief Scheme and Energy Bill Discount Scheme legislation²³. That is a specific statutory hook rather than a general power.

For a household, the practical reading is that the Ombudsman is a route to a decision and a remedy, not a route to punishment. Where a case falls outside the scheme, the alternative is the consumer code's own process or the general law.

Why an approved code matters to homeowners

The value of an approved code is that it converts a set of promises into a condition of trading. An installer that wants to deliver work under the Boiler Upgrade Scheme must be MCS certified and a member of an approved consumer code¹. That requirement is not a suggestion in a marketing leaflet; it is written into the scheme rules that govern whether a grant can be paid.

That gives a household a check that is quick and consequential. Membership can be verified, and the verification is meaningful because the grant scheme depends on it. The pages on checking an installer before you buy and on MCS certified installers set out how the certification and code checks fit together.

The second reason approval matters is that it creates a documented complaint route with defined periods. A household dealing with an unregistered trader has consumer rights but no scheme to escalate to. A household dealing with a code member has a sequence: installer, then code, then Ombudsman, each with a stated window².

The third reason is deposit protection. The £5,000 figure attached to the code is a defined ceiling that a household can weigh against the advance payment being requested¹. That is more concrete than a general assurance about quality.

The limits should be stated as clearly as the benefits. A consumer code is not an insurance policy, it does not guarantee a company's solvency, and it does not remove the need to check certification, read the contract and keep records. It is one layer in a stack that also includes MCS certification, the manufacturer's warranty, the workmanship warranty and, where a credit card was used, section 75 rights¹³.

HIES and the push for mandatory installer licensing

The direction of policy is towards tighter installer requirements, and the consumer codes sit inside that movement. The Boiler Upgrade Scheme guidance for installers states that installers must continue to hold membership with one of the two approved consumer codes, RECC or HIES, until further notice, for work under the scheme⁵. The later version of the same guidance confirms that installers not yet transitioned to the redeveloped MCS installer scheme must still hold consumer code membership with one of the other two approved codes of practice, HIES and RECC⁶.

That wording is a snapshot of a transition rather than a settled end state. The redeveloped MCS installer scheme is changing how certification is structured, and the consumer code requirement is being carried across the change rather than dropped. For a household, the practical effect is that the code requirement has survived every recent revision of the scheme rules.

The wider context is a licensing debate. No government commitment to mandatory installer licensing appears in the published documents behind this page, so no date or proposal should be assumed. What they do contain is a consistent requirement that installers working on funded domestic work belong to an approved code, repeated across property owner guidance, installer guidance and the redeveloped scheme guidance¹.

There is also a consumer protection dimension in the load control rules, which cover privately owned electric vehicles, smart charge points, heat pumps, storage heaters, heat batteries, hot water heat pumps, hybrid heat pumps and smart battery storage¹¹. As more domestic devices become controllable and more of them are sold with installation attached, the case for a code that governs the selling process rather than only the equipment grows.

For a household, the sensible position is to treat code membership as a live requirement rather than a historical one, and to check it at the point of quote rather than at the point of complaint. The pages on installer requirements for grants and funded schemes and on complaining about an installer cover the surrounding detail.