Control path
Room demand, temperature sensors, flow switches, controller logic, relays and modulating outputs must be interpreted as a sequence.
System component / controls
DEMAND. SIGNAL. RESPONSE.
HIU control diagnosis traces what the system is being asked to do, the signal produced and the physical response.
Book controls diagnosis
HIU TECH / TECHNICAL SCOPE01—03
Avoid isolated replacement
A displayed fault or absent output can result from another condition elsewhere in the system.
Attendance required
Conclusive diagnosis requires an engineer on site to measure temperatures, pressures, flow, electrical supply and control response under operating conditions.
PRIMARY 70.2°CRETURN 41.8°CΔT 28.4KFLOW 11.6 L/MIN
Measure. Diagnose. Resolve.