Taconova's TacoTherm Dual Zepto 10/26 heat interface unit (HIU) has successfully passed all four modules of the BESA UK HIU Test Regime V3-Rev002 (March 2026), demonstrating its performance against the latest test criteria and securing its place on the BESA HIU Test Register.
UKAS-accredited laboratory, Enertek International, carried out testing on a production sample. On a 70°C network, the unit recorded a domestic hot water Volume Weighted Average Return Temperature (VWART) of 17°C, against a BESA pass threshold of 20°C. Maximum hot water output was 42.0 kW.
The unit also passed on a 55°C primary network at 36.1 kW, the heat pump readiness point.
Together, the successful BESA testing and strong return temperature results demonstrate the TacoTherm Dual Zepto’s ability to support lower network return temperatures, thereby improving heat network efficiency, and providing evidence of its suitability for heat-pump-led and next-generation heating schemes.
The unit delivered hot water in 10 seconds on a 70°C network and passed every safety criterion on scalding and scaling exceedances.
Behfar Abedinia, General Manager of Taconova UK, commented: “Ofgem took on regulation of heat networks in January 2026, and technical standards follow in 2027. Specifiers are being asked to evidence performance, not assert it. Independent testing to the 2026 BESA regime gives them return temperature data they can put straight into a design case.”
The real-world reliability of Taconova's technology is already well established across major UK projects. At the £37m Ironworks residential development in Sheffield, Taconova successfully supplied 229 electronically controlled HIUs for the 12-storey building. Connected to a communal heating system, these units ensure efficient, consistent heating and domestic hot water for residents. The integration of smart metering enables remote monitoring and analysis of heat consumption, allowing building management to track system efficiency and swiftly pinpoint any network faults.
The TacoTherm Dual Zepto is an indirect, dual-service HIU providing instantaneous domestic hot water and indirect space heating. The compact, connection-ready unit (W 455mm × H 767.5mm × D 300mm) is WRAS approved. It comes prepared for heat meter installation, supporting accurate energy and cold water billing. For heat network operators, the independently verified performance demonstrated through the BESA testing, including low return temperatures, is critical, as they reduce network flow rates, pumping energy and distribution losses, significantly improving overall plant efficiency.
The full test results can be found on the BESA HIU Test Register: www.thebesa.com/test-registers/taconova
For further product information, visit: www.taconova.com/en/system-technology/c/decentralised-hiu/v/tacotherm-dual-zepto
