Heat Pump Installer Accreditation Explained UK 2026

Heat pump installer accreditation UK 2026: MCS, HIES, RECC, TrustMark, Gas Safe + what each covers.

MCS-certified heat pump installer with credential badge
Updated How we review →
By Rob Griffiths17 June 2026 · 5 min read

UK heat pump installer accreditations form a layered consumer protection system. Understanding which mark covers which risk is the difference between a smooth install and an unrecoverable refund dispute.

MCS - Microgeneration Certification Scheme

The technical baseline.

MCS is the technical product + installation quality certification mark. Established 2008. Required for:

  • Boiler Upgrade Scheme (BUS) grant eligibility (GBP 7,500).
  • Smart Export Guarantee (SEG) for solar PV (but not relevant for heat pump alone).
  • Smart-tariff registration with Octopus Cosy, Intelligent Octopus etc.

What MCS covers:

  • Heat pump unit must be MCS-certified (UK type-approval for performance + safety).
  • Installer must be MCS-accredited (annual audit + site inspections).
  • Installation must meet MCS-020 noise + MCS-007 design standards.
  • Heat-loss calc + design documentation must be filed with MCS.

What MCS does NOT cover:

  • Consumer dispute resolution.
  • Deposit protection if installer goes bankrupt.
  • Warranty claims handling.

Verifying MCS:

  • Search MCS Certified database at mcscertified.com.
  • Verify installer's MIS number on quote.
  • Confirm individual engineer's MCS card on install day.

HIES - Home Insulation + Energy Systems Contractors Scheme

Consumer protection layer (option 1).

HIES is the Home Insulation and Energy Systems Contractors Scheme - an Ofgem-approved consumer code. Provides:

  • Deposit protection up to GBP 25,000: if installer goes bankrupt mid-install, HIES insurance covers your deposit + advance payments.
  • 2-year insurance-backed warranty: on workmanship if installer ceases trading.
  • Dispute resolution service: free mediation between you + installer for technical disputes.
  • Conduct standards: HIES members must follow consumer protection codes (no high-pressure sales, fair contract terms).

Verifying HIES:

  • Search at hiesscheme.org.uk.
  • HIES membership number on quote.
  • HIES logo on documentation.

RECC - Renewable Energy Consumer Code

Consumer protection layer (option 2).

RECC is the Renewable Energy Consumer Code - alternative Ofgem-approved consumer code to HIES. Functionally similar coverage:

  • Deposit protection up to GBP 25,000 via independent insurance.
  • Workmanship warranty if installer ceases trading.
  • Independent dispute resolution.
  • Code of practice on conduct.

HIES vs RECC:

  • Almost interchangeable in coverage + protection level.
  • Choose installer with EITHER (both not required).
  • Some installers carry both, but coverage doesn't double - one valid claim per dispute.

Verifying RECC:

  • Search at recc.org.uk.
  • RECC number on quote.

TrustMark - government-endorsed quality mark

Combines technical + consumer protection.

TrustMark is the government-endorsed (BEIS / OPSS) quality mark. Required for many ECO4 + retrofit grant schemes.

  • Combines: technical certification (MCS or equivalent) + consumer code (HIES or RECC).
  • Required for ECO4 grant funded heat pumps (low-income households via PAS 2035 retrofit standards).
  • Optional for non-grant BUS installs (MCS alone suffices).
  • Verifying TrustMark: trustmark.org.uk search.

When to require TrustMark:

  • If applying for ECO4 / Local Authority Delivery (LAD) grant: yes.
  • If standard BUS-only install: optional but signals premium quality.

Gas Safe - relevant only when removing gas boiler

Required for gas infrastructure work.

Gas Safe Register (Capita-managed) covers gas appliance installation + servicing. Required when:

  • Existing gas boiler being decommissioned + isolated: gas line must be capped by Gas Safe-registered engineer.
  • Existing gas pipework being removed: requires Gas Safe to permanently disconnect at meter.
  • NOT required if hybrid system retains gas boiler (Vaillant arostor, Daikin hybrid): standard gas boiler servicing applies.

Verifying Gas Safe:

  • Engineer ID card visible on install day.
  • Gas Safe certificate + paperwork for decommissioning.
  • Check at gassaferegister.co.uk.

Most heat pump installers have a Gas Safe-registered engineer on-team or subcontract this single step.

Other relevant accreditations

Useful but not required.

  • NICEIC (electrical certification): ensures the dedicated 32A circuit for heat pump install is wired to Part P standards. Most MCS installers have NICEIC on staff.
  • HETAS (solid fuel): relevant only if installing biomass / pellet stoves alongside heat pump (rare hybrid).
  • Refcom F-Gas (refrigerant handling): required for installers handling R32, R410A refrigerants. R290 (propane) sometimes exempt - check unit specification.
  • NAPIT: electrical Part P certification scheme equivalent to NICEIC. Either is acceptable.
  • OFTEC (oil): relevant only if decommissioning oil boiler alongside heat pump install.

Checklist before signing the contract

Verifying installer credentials.

  1. MCS certificate number on quote: search at mcscertified.com.
  2. HIES OR RECC membership shown on quote: search at hiesscheme.org.uk or recc.org.uk.
  3. If ECO4-eligible grant household: TrustMark verified: search at trustmark.org.uk.
  4. If removing existing gas boiler: Gas Safe number shown: confirm before install date.
  5. Public Liability insurance evidence: min GBP 2M cover - confirm on quote.
  6. 2-year workmanship warranty in writing: insurance-backed by HIES/RECC if installer ceases trading.
  7. Manufacturer warranty terms documented: Vaillant 5-year, Mitsubishi 7-year, Daikin 5-year typical.
  8. Itemised quote breakdown: heat pump unit + indoor unit + cylinder + pipework + commissioning + grant deduction shown separately.
Q01What accreditations does a UK heat pump installer need?
Required: MCS (technical) + EITHER HIES OR RECC (consumer code). For ECO4 grant work: also TrustMark. Gas Safe required ONLY if removing existing gas boiler. NICEIC/NAPIT for electrical work covered as standard.
Q02Is MCS certification mandatory for heat pump installs?
MCS is required for Boiler Upgrade Scheme (BUS) grant eligibility - GBP 7,500 you forfeit without it. Smart-tariff registration (Cosy, Intelligent Octopus) also requires MCS install records. Non-MCS installs are legal but exclude these benefits.
Q03What's the difference between HIES and RECC?
Both are Ofgem-approved consumer codes with deposit protection up to GBP 25,000 + insurance-backed warranties. Functionally very similar. Choose installer with EITHER - both isn't required.
Q04Do I need a Gas Safe engineer for heat pump install?
Only if your existing gas boiler is being decommissioned + gas line capped at meter. Most MCS installers include Gas Safe coverage on-team. NOT required if installing hybrid (keeping gas boiler) or if home is already gas-free.