Why attendance is required
Conclusive diagnosis requires an engineer on site to measure temperatures, pressures, flow, electrical supply and control response under operating conditions.
Technical fault guide / engineer attendance
HIGH RETURN TEMPERATURE IS A PERFORMANCE SIGNAL.
Bypass, valve authority, heat transfer and secondary flow require measurement under representative load.
Book an engineer visit
HIU TECH / TECHNICAL SCOPE01—03
What the engineer establishes
The visit identifies whether the cause sits in the dwelling circuit, the interface unit, its controls or the wider building network.
Do not attempt internal checks
HIUs and CIUs contain hot, pressurised and electrically live components. Do not remove covers or attempt adjustments; request technical support.
PRIMARY 70.2°CRETURN 41.8°CΔT 28.4KFLOW 11.6 L/MIN
Measure. Diagnose. Resolve.