Enhancing Interpretability of Data-Driven Fault Detection and Diagnosis Methodology with Maintainability Rules in Smart Building Management

Table 3

HVAC System - Chiller Plant.

Problem	Design	Construction	Maintenance
Chiller frequently unloading (stop-start); compressor not starting; Rust stain; Leaking condenser pipes	Conform to the minimum requirements for air- conditioning equipment efficiency in accordance with SS 530: 2014, ANSI/ASHRAE/IES standard; 90.1 or equivalent.; Specify proper placement for installation of temperature sensors/probes to capture realistic average temperatures of spaces.; Conform to the safety and environmental requirements for refrigeration systems in accordance with ISO 5149-1 or equivalent.	For applications with high dynamic load conditions of a facility, install and commission chillers with variable speed drive (VSD) compressors.; Ensure that schematics and maintenance regime of refrigerant leak detection system is handed over to maintenance personnel upon completion.	Set up appropriate cut-in and cut-out temperatures in chiller to avoid frequent unloading.; Inspect evaporator tubes for excessive oil, dirt or frost; check operating condition of expansion valve; check condenser tubes for air, dirt, scale, and sludge, and clean/purge if necessary. Check condenser water supply and cooling tower efficiency. Inspect overload relay, and the condition of high- pressure and low- pressure cut-outs.; Carry out monthly inspection on refrigerant level to avoid low pressure cut-outs of chiller in accordance with ANSI/ASHRAE/ACCA standard; 180 or equivalent.
Insufficient cooling/slow cooling; Scale in condenser pipes; No insulation for chilled water pipe; Leakage of refrigerant	Design chiller plants for recommended cooling; Demand with provisions for future expansions guided by SS 553, SS554, AS1668.2, ISO16814 or equivalent.; Comply with air conditioning plant optimisation strategies (e.g. high-efficiency chillers, aggressive condenser water reset, medium temperature chilled water loop, chilled water VFD pumping, etc.) in accordance with SS564-1 or equivalent.; Use refrigerants with zero ozone depleting potential (ODP) or global warming potential (GWP) of less than 100 [7]. Recommend installation of leak detection system in critical areas of plant rooms.	Cary out proper commissioning of chiller plant and set reasonable points. Perform post-installation monitoring of the installed instrument’s performance through the BMS (building automation system) or EMS (energy measurement system).; Document as-built drawings (including concealed services) for building user phase. Prepare and handover maintenance checklists for service and repair of each instrument during commissioning. Refer to measures for recommended monitoring procedures for chiller efficiency in accordance with SS 591 or equivalent.	Inspect temperature controllers and thermostatic control valve for any malfunctions and then reset.; Perform routine inspection of condenser pipes. Carry out cleaning and servicing (de-scaling) if/when necessary.; Routinely inspect insulation for any damaged/worn-out layers. Daily logging of chiller system to ensure system operates at optimum conditions. Any deviation from the intended chiller operation or alarms need to be attended promptly.; Perform annual shutdown or overhauling in accordance with manufacturer’s guidelines (ANSI/ASHRAE/ACCA standard 180).
Chilled water pipe and condenser pipe leakage and condensation; Leaking motor valve	Adopt the pump system design calculation and recommend outputs in accordance with ISO 13612-1 or equivalent.; Specify the use of unplasticized PVC pipes for cold water services/industrial use as in accordance with SS 141 or equivalent.; Provide flow meters for chilled/condenser water loops.	Ensure proper workmanship during pipe installation and testing, especially at joints.; Perform proper insulation of chilled water pipes to avoid condensation.; Use primary-only variable flow chilled water pumping systems in accordance with SS 564-1 or equivalent.	Cary out quarterly check for pitting noise in pumps. Avoid harsh cleaning methods that may damage pipes or cause the thinning of pipes.; Prepare maintenance checklist for flow meters (ultrasonic and full-bore magnetic in-line types) in accordance with SS 591, ISO 12242 or equivalent.