Part 3: Repair vs. Replacement Decision Requires Advance Planning
Repair vs. Replacement Decision Requires Advance Planning
By Angela Lewis and David Cosaboon August 2013 - Power & Communication
It might not be economical for most facilities to collect detailed data about motors and drives to populate a CMMS, so the next best approach is to create a plan managers can use consistently when making repair-or-replace decisions. The plan should address such questions as:
- How large is the motor or VFD?
- What does the motor or VFD serve?
- About how old is the motor or drive?
- What is the component's expected service life?
- What is known about the maintenance history?
For small motors, it is generally most economical to simply replace the motor. For large motors used in some institutional facilities or campuses, the most cost-effective decision can be to repair or rebuild both small and large motors. The key is to estimate when the cost of repair and current levels of maintenance exceed the cost of replacement.
If a manager does not know the installation date of the motor or drive, the next step is to estimate the date by determining the installation date of the parent asset and comparing the visual appearance and any wear on the motor or drive to the parent asset. For example, if a chilled-water pump was installed when the building was constructed and the motor looks to be the same age as the pump, it might be safe to assume the motor and the pump are the same age. Asking the maintenance technicians who have been at the facility for the longest time about the history also can be especially valuable.
Whether or not to repair VFDs will depend on their condition. VFDs are electronic, so they have fewer moving parts that can fail. But if the drive has truly failed — if its control panel no longer functions, for example — the general practice is to replace it.
Another way to estimate the expected service life is by reviewing industry resources that provide the service lives for different systems. These resources include:
- 2011 ASHRAE Applications Chapter 37: Owning and Operating Costs, which provides estimated service lives for HVAC systems of various sizes, including heat pumps, boilers, chillers, pumps, controls and valve actuators
- RS Means Facility Maintenance and Repair Cost Data
- Whitestone Research Maintenance and Repair Cost Reference
- ASHRAE service life and maintenance cost database.
- ANSI/ASHRAE/ACCA Standard 180-2012: Practice for Inspection and Maintenance of Commercial Building HVAC Systems, which helps managers align maintenance with manufacturer recommendations and general industry practices.
If a manager determines it is necessary to replace a motor or drive, the two most important pieces of data are the manufacturer and model numbers. Managers can use them to determine name plate data, such as horsepower, efficiency, voltage, revolutions per minute, and current. Similarly, the manufacturer and model number are essential information to know when replacing a VFD.
Increasingly, the construction profession is using the electronic delivery of construction documents, condition assessments and asset inventories transitions, and this information is moving from PDFs to machine-readable formats using open information-exchange standards. As a result, the level of detailed data also is increasing.
But until maintenance and engineering managers require open information exchange standards, such as the Construction Operations Building information exchange (COBie), and use them in software, the most economical practice for collecting and managing detailed data on motors and drives will be for managers to collect data from the field as needed and use it consistently within the decision-making process.
Angela Lewis, P.E., LEED AP, is a project manager with Facility Engineering Associates (FEA) in Fairfax, Va., specializing in facility management technology. David Cosaboon, CEM, LEED AP O+M, is a project engineer with FEA in Fairfax, Va. Mayra Portalatin, a project manager with FEA, contributed asset-inventory and condition-assessment expertise to this article.