Two guidance documents have been produced by the Building Engineering Services Association (BESA) to help simplify some of the complexities of interpreting test results for Heat Interface Units (HIUs).
BESA’s UK HIU Test Regime, which was expanded and enhanced in 2023 and is due to be updated again before the end of this year, gives HIU manufacturers an independent method for testing, assessing, and comparing the performance of products.
It has improved product performance by providing specifiers with the necessary information to make fully informed decisions. BESA tested HIUs are also included in the Heat Network Technical Standard (TS1).
However, the results presented in the test reports are often complex to interpret, making it hard for many specifiers to accurately evaluate HIU performance. This can result in an overreliance on simplified metrics, such as volume-weighted average return temperatures (VWARTs).
With more than 50,000 HIU’s now being installed in the UK annually and the government’s Heat Network Technical Assurance Scheme (HNTAS) coming into force next year, having easy to interpret performance data is an increasingly important concern for the expanding heat network industry.
HIUs make use of the heat from district heating networks to feed individual buildings and dwellings and the way they perform is central to the overall efficiency of the system.
So, BESA has now produced two new pieces of guidance to help users interpret test results. The first is a summary document that provides a brief overview of the structure of the main guidance document and highlights key considerations to be made when interpreting the results.
The main guidance document focuses on interpreting the results for Modules 1 and 2 (indirect space heating) and 7 and 8 (domestic hot water). It provides a description of the test, a discussion of its purpose and context, pass/fail criteria and best practice benchmarks. It also demonstrates how to interpret performance from test output graphs.
Guidance author Ethan St. Catherine said the documents would help HIU specifiers and consumers interpret BESA test results in depth, rather than relying on individual metrics.
“This ensures that informed decisions are made, based on a comprehensive understanding of HIU performance, and represents a key step toward improving performance standards and delivering better outcomes for end users,” he added.
Testing to the BESA standard allows the performance of different HIUs to be evaluated in typical UK operating conditions and provides evidence of compliance with other performance and reliability metrics, such as domestic hot water response times.
The result is verified by a BESA technical consultant before being published on the BESA HIU Test Register. The information is then available to help specifiers make informed decisions about the type of HIUs to select for their projects.
The regime is run as a not-for-profit project by BESA and all the income from testing is invested back into the future development of the scheme. Any manufacturer who decides to publish their test results on the Register database can claim that they are ‘BESA registered’ and can use the Association’s logo.
The new guides can be downloaded here.
