When a facility owner has a building program approved to move forward to the design phase, a design team needs to be contracted to produce the contract documents. At that point, the project delivery method should be decided too. Why? Well in the 2020 ASHRAE Handbook, HVAC Systems and Equipment, Chapter 1, HVAC System Analysis and Selection, there are five different project delivery methods to choose from. One can research each method and decide which would be preferred:
- Design-bid-build;
- Construction management;
- Design-build;
- Integrated project delivery; and
- Performance contracting.
No matter the project delivery method, the HVAC equipment, and systems, as well as the other infrastructure equipment and systems, will require owners’ manuals (O&M manuals). To comply, these owners' manual requirements must be included in the final contract documents that go out to bid. The design team’s consulting engineer will most likely use the company’s standard O&M manual specification as an insert in the contract bid documents.
Quite often, this “canned” specification is edited for the application, but, unfortunately, the HVAC “spec” writer may not coordinate his or her company's O&M manual specification criteria with the upfront Division 1 specification drafted by another spec writer who overlooks the HVAC specification in the contract documents. This will be further discussed in next month’s “Tomorrow’s Environment” column.
Regardless, if the two spec writers communicate with each other or not, what is usually missing from both O&M manual specifications is a consideration to incorporate predictive maintenance requirements. What is predictive maintenance? It’s a “measurement-based” process using data collected by the building automation system (BAS) and/or handheld devices.
Unlike the traditional, time-based preventive maintenance (e.g., replace air filters quarterly), predictive maintenance methods include but are not limited to performance trending, testing, and recording methods. What would a facility manager want to know via trending data and/or spot checking equipment and materials? The following items should be considered.
- Fan shaft vibration that may go unnoticed and shorten the useful service life of the fan shaft;
- Ultrasonic measurement picking up and helping to differentiate an equipment sound pattern, e.g., pump bearings, etc., and
- Motor analysis techniques to assist in raising awareness to a potential motor fault.
Other predictive maintenance methods:
- Oil analysis has been around long before preventive maintenance. Computerized maintenance management software (CMMS) systems were developed to assist in proactive maintenance of the equipment and systems. Sampling the oil condition for lubricating performance, and by testing its viscosity and corrosion inhibitors, allows the facility management to make important operating decisions.
- Eddy current testing is used to detect, identify, and locate signs of weakness in refrigeration equipment’s internal components. Ultrasonic testing is another nondestructive method used to determine wall thickness for corrosion and erosion.
- Infrared thermography provides images the human eye can’t see. A radiometer can produce an infrared photo showing excessive cold air above a ceiling or behind a wall from outdoor air infiltration. This device can also be used to visually recognize a faulty steam trap.
As a rule, predictive maintenance criteria doesn’t make it into a building program’s contract document specification, and, yet, on occasion, some of these devices should be considered, especially if the building program is based on a facility projected to have a useful service life of 20-30 years.
