Installer Schemes and Consumer Codes: TrustMark, RECC, HIES and Others

Three separate systems stand between a householder and a badly done energy installation, and they are easy to confuse. Technical certification, chiefly MCS, says a product and an installer meet a performance standard. Consumer codes, run by HIES and the Renewable Energy Consumer Code, set rules on how the work is sold, contracted and guaranteed. TrustMark sits above both as the only UK Government Endorsed Quality Scheme, the register that government schemes point to when they require an installer to be registered¹.

The practical consequence is that a householder checking an installer usually needs to check two things, not one. Membership of HIES or RECC is a condition of MCS certification, so an MCS installation company working with domestic customers must also be a member of a consumer code approved by the Trading Standards Institute². Under the Boiler Upgrade Scheme, installers must continue to hold membership with one of the two approved consumer codes, RECC or HIES, to deliver work³.

What the codes buy a household is mostly procedural: a defined cancellation period, an insurance backed workmanship warranty of at least two years, and a complaint route that ends in independent arbitration rather than a dead letter⁴. What they do not buy is a guarantee against a company failing, and the protections are not identical across the four nations or across schemes.

What TrustMark, RECC and HIES are, and how they differ

The three names describe two different layers of protection, and the difference matters when something goes wrong.

TrustMark is the framework. It is the only UK Government Endorsed Quality Scheme, and it operates under licence from the Government's Department for Business and Trade, overseen by an independent Board⁷. It is a not-for-profit social enterprise receiving a small fee from Scheme Providers for each Registered Firm that joins, and it holds the right to suspend or remove Registered Businesses from the scheme⁷. TrustMark does not itself register installers directly in the way a householder might assume: it audits the Scheme Providers every year to ensure continued compliance with the Framework Operating Requirements⁷.

HIES and RECC are the consumer codes, and they are the bodies an installer actually joins. HIES is a TrustMark Scheme Provider, and it operates and manages the Quality Scheme under which TrustMark Registered Businesses are registered, including oversight of standards and complaint handling¹. The Renewable Energy Consumer Code was formed in 2006, was developed and is sponsored and run by Renewable Energy Assurance Ltd, and is backed by the Chartered Trading Standards Institute⁹. Its scope is the selling or leasing of small-scale heat and power generators, whether from renewable or other low carbon sources, to domestic consumers⁹.

So the structure runs: government endorses TrustMark, TrustMark licenses Scheme Providers such as HIES, and the Scheme Providers run the quality scheme that individual businesses join. RECC sits alongside as a code approved by the Chartered Trading Standards Institute, and it dovetails with MCS⁹.

TrustMark: the Government Endorsed Quality Scheme

TrustMark's standing comes from government use of it rather than from statute. Ministers have advised using builders registered with TrustMark, describing it as a trusted scheme to ensure work is done properly¹⁰. In Scotland, the Heat in Buildings strategy committed to considering the UK Government endorsed TrustMark quality assurance framework¹¹.

That endorsement has been written into funding conditions. Installers under UK Government schemes must be TrustMark registered and/or MCS certified⁶. Under the Warm Homes: Social Housing Fund, all installers are required to be TrustMark registered, or equivalent, and compliant with corresponding requirements set out on TrustMark's website¹². Under the Green Homes Wales loan scheme, the installer contracted to supply and install eligible measures must be registered with TrustMark and must remain registered until the installation work has been completed¹³.

The register is also the route local authorities point households towards. Leeds City Council advises considering a competent person register such as TrustMark, the Government Endorsed Scheme for work done around the home, to find an installer that will assess circumstances and the property to identify suitable measures¹⁴.

TrustMark's own reach is measurable. Around 14,700 Warm Homes: Local Grant measures were lodged in the TrustMark data warehouse up to the end of July 2026, covering around 6,700 households¹⁵. That figure is a useful gauge of how much government-funded work now passes through the register, and therefore how much of it carries the associated warranty floor.

What TrustMark registration means for your work and your money

Registration is a claim about a business's conduct as well as its competence. A TrustMark Registered Business carries assurance of standards in technical competence, customer service, and trading practices, and gains permission to use the TrustMark logo across marketing materials¹. Installers that are TrustMark Registered Businesses carry out the work directly for customers¹.

The money side is narrower than the branding suggests. TrustMark states there should be no premium for using a TrustMark Registered Business⁷. The scheme is funded by a small fee from Scheme Providers for each Registered Firm that joins, not by a levy on the householder⁷. Where quotes differ, the difference lies in the businesses, not in the registration.

On guarantees, TrustMark sets a floor for work done under certain schemes: a minimum two-year warranty for work, and a minimum 25-year guarantee for certain measures installed under the ECO⁶. For works completed and lodged under government-funded or capital schemes, the route to a guarantee runs through the Registered Business first, then their Scheme Provider, then TrustMark itself for a copy of the guarantee information⁷.

Registration is not permanent and not unconditional. TrustMark has the right to suspend or remove Registered Businesses from the scheme, and it audits Scheme Providers annually⁷. A householder checking a business today is checking a status that can change.

TrustMark's Find and Fix service and the CES support route

TrustMark's consumer-facing role extends beyond the register. The Department for Energy Security and Net Zero confirmed that it nominated TrustMark to directly support customers of CES⁸. TrustMark provides an online form for that support route⁸.

The wider direction of travel is consolidation. A government consultation proposes a unified, end-to-end consumer protection service for all DESNZ-supported home upgrades, bringing together responsibilities for all retrofit measures under one service, with many functions currently carried out by TrustMark and MCS instead performed by the new service¹⁷. That proposal is not yet in force, and it would change the shape of the landscape described here if implemented.

In Scotland, the Heat in Buildings Quality Assurance Statement records that both TrustMark and MCS have launched reviews of their consumer standards and redress processes, with the aim of ensuring the processes align¹⁸. The same statement records an intention to investigate the development of an online portal powered by TrustMark and MCS to help consumers find approved suppliers in Scotland¹⁹.

For a householder, the practical point is that the support and redress architecture is in motion. The register, the codes and the complaint routes exist now; the consultation signals that their division of labour may not be permanent.

RECC: the Renewable Energy Consumer Code and what it covers

The Renewable Energy Consumer Code is the more detailed of the two consumer codes on the sales process. It sets 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 consumers⁹. Its coverage runs across marketing, pre-contractual information, quotations, deposits, contracts, guarantees and after-sales service⁹.

That list is the answer to a common question about what a consumer code actually does. It does not certify that a heat pump will perform to a stated efficiency, which is MCS's territory. It governs the sequence of events from the first sales contact to the after-sales service, which is where most disputes originate.

RECC was formed in 2006 and is sponsored and run by Renewable Energy Assurance Ltd, and it is backed by the Chartered Trading Standards Institute⁹. It dovetails with MCS, so the two are designed to be read together rather than as alternatives⁹.

RECC also appears in scheme administration beyond installer conduct. Ofgem worked with RECC to provide a model agreement for the Metering Monitoring Service Package under the Domestic Renewable Heat Incentive²⁰. That is a reminder that the code's influence reaches into scheme paperwork, not only into contracts with householders.

Membership is not optional for installers working under the Boiler Upgrade Scheme. Installers must continue to hold membership with one of the two approved consumer codes, RECC or HIES, to be able to deliver work under the scheme³. Installers who have not transitioned to the MCS Redeveloped Installer Scheme must still hold consumer code membership with one of the other two approved codes of practice, HIES and RECC²¹.

RECC protections: deposits, cancellation and workmanship guarantees

The protections that matter most to a householder are the cancellation window and the workmanship warranty, and both have conditions attached.

On workmanship, RECC requires an insurance backed workmanship warranty, valid for at least 2 years⁴. The insurance backing is the significant part: it is designed to survive the installer, which a bare promise from the company does not.

On cancellation, the period is 14 days, but when it starts depends on how the contract was signed⁴:

Starting work early has a cost consequence. If the installation is to start during the cancellation period, express written consent is required, and cancelling later means paying for any work completed⁴.

Beyond the code, general consumer law adds routes. Consumer protection helplines cover faulty goods, poor service, contracts, building work, rogue traders, credit and store cards, counterfeit goods and fraud, and complaints can be referred to local Trading Standards Officers who may then investigate²². Complaint information is shared nationally with enforcement authorities including Trading Standards, the Competition and Markets Authority and regulators, so that action can be taken²².

HIES: the Home Insulation & Energy Systems contractors scheme

HIES is the other approved consumer code, and it is also a TrustMark Scheme Provider¹. It complies with the operating requirements of a quality scheme designed to give homeowners confidence when choosing an installer¹. Because it operates and manages the Quality Scheme under which TrustMark Registered Businesses are registered, its role includes oversight of standards and complaint handling¹.

HIES appears in scheme rules in the same places as RECC. It is one of the two consumer codes relevant to the Boiler Upgrade Scheme⁵. Under the Domestic Renewable Heat Incentive, before registering, an investor must be a member of the Renewable Energy Consumer Code or the Home Insulation and Energy Systems Quality Assured Contractors Scheme, both CTSI approved consumer protection codes²³. That requirement has been consistent across scheme years, appearing in both the 2023-24 and Scheme Year 11 annual reports²³.

The two codes are treated as interchangeable for eligibility purposes in most scheme documents, which is why the choice between them is usually the installer's rather than the householder's. What differs is the internal process: HIES complaints can be referred to TrustMark, which may review whether the correct procedures have been followed by HIES as the Scheme Provider, though TrustMark does not investigate individual complaints or award compensation¹.

For a householder, the practical test is not which code sounds stronger but whether the business is a member of either, and whether the code's dispute route is one they are willing to use.

Which scheme covers which job: TrustMark, RECC or HIES

The three names are not alternatives to choose between. They apply at different points, and most government-funded work touches all of them.

The pattern is that TrustMark registration is the condition attached to public money, while consumer code membership is the condition attached to MCS certification and to the Boiler Upgrade Scheme. A householder receiving a grant will usually be dealing with a business that holds both.

There is a devolved dimension. In Scotland, the Heat in Buildings strategy committed to considering the UK Government endorsed TrustMark quality assurance framework, and to investigating a joint TrustMark and MCS portal for finding approved suppliers¹¹. In Wales, the Green Homes Wales loan conditions tie registration to redemption of the loan, requiring confirmation that the necessary lodgements have been submitted to TrustMark¹³. In England, local authority guidance points households to competent person registers including TrustMark¹⁴.

How to complain: dispute resolution, arbitration and the ombudsman

The complaint route has a defined order, and skipping a step usually slows things down.

For installation quality, workmanship or the behaviour of an installer, the first step is the installer, then the installer's consumer code, HIES or RECC, or MCS installation quality complaints²⁵. RECC offers a mediation service and an independent arbitration service, which members must cooperate with⁴. That obligation to cooperate is what gives the route its force: a member cannot simply decline to take part.

Where the complaint concerns a scheme's own handling, the route can go further. A complaint about HIES's procedures as Scheme Provider can be referred to TrustMark, which may review whether the correct procedures have been followed, though it does not investigate individual complaints or award compensation¹.

General consumer complaints have a parallel route through Trading Standards. Complaints can be referred to local Trading Standards Officers who may then investigate, and complaint information is shared nationally with enforcement authorities including Trading Standards, the Competition and Markets Authority and regulators²².

For heat networks, a separate regime applies, with authorised persons' complaint handling procedures required to contain details of the Relevant Dispute Resolution body and the instances in which a consumer should contact them²⁶. That is a different route from the installer codes and applies to heat network customers rather than to individual installation contracts.

For Energy Company Obligation and Great British Insulation Scheme households, Ofgem runs a contact route: a freephone number, 0808 169 4447, Monday to Friday excluding bank holidays, from 9.30 am to 4.30 pm, alongside an email address and a webform²⁷.

Contacting the schemes: phone, email and opening hours

Contact details for the codes and schemes are published, and using the right one saves time.

Ofgem's Boiler Upgrade Scheme property owner guidance was updated to include content and contact information concerning consumer codes, including MCS, HIES and RECC, and a later summary of updates notes that it adds direct contact routes for HIES and RECC in a more concise format²⁹.

The opening hours published for the Ofgem ECO and GBIS line are the only hours given for any of these routes. For TrustMark, RECC and HIES, the published details are a phone number and, for two of them, an email address, without stated hours.

What the schemes do for a household's energy independence

The consumer codes and TrustMark do not generate a kilowatt hour, and they do not reduce a household's dependence on the grid, a supplier or imported gas. What they do is protect the money and the workmanship that go into equipment a household owns, which is the part of energy independence that is within a household's control.

The protections are real but bounded. An insurance backed workmanship warranty of at least two years under RECC, and a minimum two-year warranty with a minimum 25-year guarantee for certain ECO measures under TrustMark, mean a defective installation has a route to remedy that does not depend on the installer still trading⁴. A 14-day cancellation period with defined start dates gives a householder a window to withdraw⁴. Mediation and independent arbitration, which members must cooperate with, give a dispute somewhere to go⁴.

The dependence that remains is on the scheme's own continuity and on the installer's membership staying current. TrustMark can suspend or remove Registered Businesses, and it audits Scheme Providers annually⁷. Membership requirements under the Boiler Upgrade Scheme are stated as continuing until further notice³. A government consultation proposes replacing much of this architecture with a unified service, which would move functions currently carried out by TrustMark and MCS into a new body¹⁷.

For a household, the honest summary is that these schemes shift risk rather than remove it. They make an installer's conduct checkable, its warranty insurable and its disputes arbitrable. They do not make an installation independent of the company that did it, and they do not survive that company's failure in every respect.