Handbook of air conditioning and refrigeration / Shan K

32.6 CHAPTER THIRTY-TWO
val between two maintenance programs depends on the operating hours of the HVAC&R system;
dirt accumulation in the filter, coil, and distribution devices; and recalibration requirements of the
instruments. For small and complicated HVAC&R systems, whenever the operator cannot repair
and service the HVAC&R system, the owner or the facility manager should ensure that qualified
contractors are hired for maintenance.
For more complicated medium-size multizone HVAC&R systems, operating personnel are often
responsible for HVAC&R system maintenance. The maintenance programs should be detailed in
the operation and maintenance manual and tailored to each specific building. For highly technical
equipment and systems, an outside maintanance contractor with the specific expertise required
should be called for service.
For large HVAC&R systems with central plants, a management organization with one operations
person and one maintenance person is required. Computerized maintenance programs should be used
to provide detailed timing of system maintenance procedures. Logged information and proper data
management associated with predictive maintenance will reduce failure response requirements. An
outside maintenance service contractor with specific expertise may need to be called.
Monitoring and Fault Detection and Diagnostics Assisting
Predictive Maintenance
REFERENCES
As discussed in Sec. 5.15, in EMCS and fault detection and diagnostics, many operating parameters
of the HVAC&R system are monitored and measured. Addition of necessary monitoring parameters
for predictive maintenance may be considered.
Faults occur when the actually measured parameters deviate from the normal operating values.
Performance degradation is an evolving fault accumulated during a certain period of time.
By using rule-based expert systems, autoregressive with exogenous inputs (ARX) models, and
artificial neural network (ANN) models, performance degradation and faults can be determined,
and the corrective maintenance action recommended.
HVAC&R maintenance is already an important part of optimizing an energy-efficient HVAC&R
system operation, to improve IAQ, and to maintain a safe, healthy, and comfortable indoor environment.
More and more computer software will be developed to combine optimizing, energy-efficient
HVAC&R system operation and predictive maintenance in the future.
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