HIU Commissioning Records

Accurate commissioning records for Heat Interface Units (HIUs) are the foundation of metering accuracy, asset management, and regulatory compliance for heat network operators. This page sets out what records should be captured at commissioning and why they matter.

What to record at HIU commissioning

Each heat interface unit commissioning record should capture:

• Property address and unique reference
• HIU make, model, and serial number
• Heat meter serial number and meter factor
• Date of commissioning and commissioning engineer
• Flow and return temperature settings
• Differential pressure settings
• Domestic hot water temperature at point of commissioning

These records form the baseline for ongoing metering accuracy, fault diagnosis, and asset management across the network.

Why commissioning records matter for Ofgem authorisation

Accurate metering is fundamental to the consumer protection framework under Ofgem's authorisation conditions. Operators must be able to demonstrate that billing is based on accurate meter readings and that meters are properly calibrated and maintained. Commissioning records provide the foundational evidence for this.

The Heat Networks (Market Framework) (Great Britain) Regulations 2025 (SI 2025/269) require operators to maintain adequate operational records. Deficiencies in asset and metering records are a compliance risk during Ofgem inspection and enforcement.

How the HNC HIU Tool manages commissioning data

The HNC HIU Tool provides a structured record for each commissioned HIU, linked to the property and network asset register. Records are retrievable by property, meter serial number, or commissioning date. The tool follows CIBSE CP1 (2020) test procedures and generates digital commissioning certificates with pass/fail validation against site-specific design parameters.