Handbook of air conditioning and refrigeration / Shan K

intent. The CC also makes sure that during verification testing, the temperature, pressure, fluid flow,
control system signals, and actions are commissionable and included in the design.
Second, postconstruction commissioning is most prevalent recently. Postconstruction commissioning
often requires at least 1 year after the completion of the construction so that both summer
cooling and winter heating mode operations can be included. In this case, the commission consultant
is most often an outsider who was not involved in the problems and politics of the design and
construction. Therefore, conciliatory and professional interpersonal skills are extremely important
for a CC. The CC also will learn about, evaluate, test, and document the installed HVAC&R system
and become involved in the operators’ training.
Third, existing building recommissioning helps to reduce HVAC&R energy consumption, improves
IAQ, and improves indoor environmental control.
Cost of HVAC&R Commissioning
Because the HVAC&R commissioning process is still being developed and standardized, a rule of
thumb for HVAC&R commissioning cost is between 2 and 5 percent of the construction cost of the
systems to be commissioned. The cost of HVAC&R commissioning can be set aside as an independent
budget item or added to the architectural/engineering or contractor fees. The commissioning
cost will be recovered by reductions in change orders and claims.
32.2 HVAC&R MAINTENANCE
Basics
HVAC&R maintenance is the work required to maintain or restore HVAC&R systems, including
equipment, instrumentation, components, and materials, to condition such that they can be effectively
operated to meet specified requirements.
ASHRAE Handbook 1999, HVAC Applications, defines repair as to make good or restore to
good or sound conditions, and defines service as what is necessary to effect a maintenance program
short of repair. In the ASHRAE handbook, maintenance also is classified into the following categories:
● Run-to-failure is a kind of arrangement such that no money is spent on maintenance prior to
equipment or system breakdown.
● In planned maintenance, all functions and resources in this category must be planned, budgeted,
and scheduled. Planned maintenance can be subdivided into preventive and corrective maintenance.
Preventive maintenance is a kind of scheduled maintenance for an HVAC&R system,
equipment, or components, in order to maintain durability, reliability, efficiency, and safety. In
corrective maintenance, corrective action is often the remedial action performed before failure occurs.
Corrective action taken during a shutdown in response to a failure is called a repair.
● Predictive maintenance is based on equipment and system monitoring, the operating conditions,
and performance to discover faults and degradations and thus the remedy performed.
Most manufacturers give detailed instructions in how to operate and maintain the specific equipment
and instruments. These instructions must be followed.
Maintenance Contractors and Maintenance Personnel
COMMISSIONING AND MAINTENANCE 32.5
In most small facilities with comparatively simple HVAC&R systems, outside maintenance contractors
often provide maintenance service based on the specified maintenance program. The time inter-