Verification checks are an important prerequisite to functional testing. In the field, verification checks are often referring to as pre-start checks, start-up checks, or pre-functional tests. Regardless of the specific terminology used, these items consist of necessary checks prior to activating a system or immediately subsequent to its activation to ensure that it is safe to operate and ready for the more rigorous processes associated with a functional test. Typical examples of this type of check include:
· Verifying piping and wiring connections
· Verifying calibration and sensor locations.
· Verifying safety settings.
· Flushing and static pressure testing of piping systems.
· Verifying belt tension.
· Verifying electrical parameters like voltage and amperage.
· Verifying pressure and flow ranges for utility and support systems.
This section describes different ways in which verification checks are handled by commissioning providers, including delegating to contractors and factory testing.; And how this relates to system readiness. And ends with checklist.
Most of these verification checks are specific to the make and model of the equipment and are usually well addressed by the manufacturer’s installation and start-up documentation. Thus, most commissioning practitioners simply rely on the manufacturers information for these checks, supplemented by insights gained in the project team’s past experience. It is not unusual for the commissioning provider to delegate the responsibility for developing the necessary verification checks to the contractors and their suppliers, providing only editorial input and coordination to the process followed up by spot checks to ensure documented compliance with the requirements. The development of verification checks depends on a variety of factors including the contractual arrangements with the installing contractor and the commissioning provider, the type of systems and equipment associated with the project, the complexity of the system, and the level of rigor required.
Each chapter of the Guide will direct the user to test procedures in the CTPL that may include verification checks appropriate to the chapter’s topic. Many of the functional tests in the CTPL include verification checks in their list of prerequisites. The CTPL also contains some separate documents for verification checks, as summarized in Appendix A Overview of the Commissioning Test Protocol Library.
The information and test procedures in the Functional Test Guide assume that the necessary pre-functional verifications are addressed by the equipment manufacturers or by tests in the CTPL. The Functional Test Guide only discusses critical or unique pre-start or start-up considerations when the checks will have a significant impact on the functional testing, represent areas that are not well covered by typical manufacturer checklists or verification checks currently available in the CTPL. The Verification Checks checklist provided in Section 7.2 can be appended with requirements listed in the CTPL verification checks, or the test writer’s own verification checks.
Seismic restraint is one area that is not well addressed by the verification checks included in the CTPL. Section 17 Supplemental Information contains information to be used as a starting point for commissioning providers charged with seismic verification.
The following generic checklist has been developed to aid in documenting the completion of the verification checks. It is arranged to allow the test executor to check off the requirement after collecting a certification letter from the various parties responsible for the major subsystems. A dated signature is used to document completion of individual items not related to any particular subsystem. This form could be used “as is” or tailored by the user to meet the needs of their project and process via editing.
For larger facilities and/or facilities with specialized air handling needs, it is not unusual for the air handling system to be a custom fabricated unit to meet the specific project needs. For this class of equipment, it is often desirable an Owner’s representative, a design engineer’s representative, the commissioning provider, and a mechanical contractor’s representative to inspect the unit at the factory prior to shipment. Factory testing large or highly customized air handling systems provides the following advantages:
· Factory testing can be witnessed by the parties with the highest level of interest in the outcome. Factory tests for air handling equipment typically include leakage testing, capacity testing, variable speed drive testing, and verification checks for factory-installed controls. By witnessing the verification testing of critical performance parameters, the designer, Owner, and contractor can feel confident that the special performance features that were purchased have been provided. The air handling unit manufacturer also has a vested interest in this test approach because it allows them to document that the unit as shipped met the project specifications and limits their liability for defects that may show up in the field due to improper shipping, handling, or installation. The factory often provides a better test setting than the construction site since special instrumentation required is readily available.
· Design, operation and maintenance features can be verified prior to the unit’s shipment and corrections can be made at the factory. Even with a detailed specification and submittal review process, misinterpretations can occur. Occasionally a special feature does not work out as anticipated. Detecting these problems in the factory allows them to be corrected in a controlled environment by people intimately familiar with the required fabrication processes. Most equipment manufacturers will have a vested interest in this approach because they avoid the costs associated with sending a skilled craftsman out to the field to correct a deficiency not caught by their own quality control process.
In some instances, limited field-testing will be required to re-verify some of the factory test items. This is especially true for larger units that must be disassembled for shipment. The responsibility for correcting problems that show up in these re-tests usually falls to the contractor, not the equipment supplier. If the unit was not factory tested, the lines of responsibility for correcting problems uncovered in the field can become controversial, especially if the problems are not immediately discovered.
Some components associated with air handling systems, like variable speed drives for example, may require factory assembly and start-up or factory supervision of the parties performing the work on the unit after it arrives at the project site. This requirement may be invoked by the Owner or the designer as a quality assurance process, or it may be a requirement of the manufacturer. In any case, there are several commissioning issues related to this work that should be considered.
1 The start-up plan needs to coordinate these requirements into the start-up schedule. In addition, good planning and coordination will ensure that all prerequisites required by the factory for their work are in place and verified prior to their arrival. If the factory representatives travel to reach the project site and the equipment is not ready, then they will be unable to perform their work in a timely manner and the entire project start-up may be delayed. In addition, the factory may seek reimbursement for their costs associated with travel to and from the site as well as lost time if they arrive and cannot perform the intended work.
2 As can be seen from the story in the sidebar, the involvement of a factory service technician in the reassembly process does not guarantee that something will not be misinterpreted or go unnoticed. Include time and steps in the start-up procedure to have a “second set of eyes” inspect and verify critical items can be desirable and provide redundancy.
3 For some machines, there may be requirements associated with a proper and safe start-up that may be less obvious to someone who is not intimately familiar with the equipment. In fact, this is one reason for including a factory start-up requirement in the project specifications or manufacturers start-up requirements.
In addition to pre-start and start-up checks, some components may require adjustment or inspection during the initial hours of operation. In some cases, someone with special training, typically the factory service representative, must make these adjustments. Some of these procedures may be critical to preventing damage to the machinery during the initial run cycle and subsequent testing and operation. Examples include:
· Re-tensioning of belts after their initial run-in period.
· Oil changes for oil lubricated bearings or gear boxes after the initial run-in period.
· Blade security checks for the locking bolts on axial fan adjustable pitch fan blades after the initial run-in period.
It may be necessary to adjust the start-up schedule and functional testing plan to accommodate requirements of this type.
The start-up and testing of air handling equipment is usually dependent on several other systems in the building being operational. Typically, these include:
Successful testing of the air handling system will require that these related and supporting systems be online, tested, and functional, so that the testing of the air handling equipment will not be adversely impacted by deficiencies in its supporting utility systems. However, on projects with fast paced schedules and multiple construction phases, full commissioning of the utility systems is often not possible. For instance, it may be necessary to start up and commission an air handling system in an office building during the fall months in order to meet a December occupancy deadline. This start-up could occur without functional refrigeration systems since the economizer cycles could provide the necessary cooling during the winter months. However, proceeding in this manner has risks, as discussed in the side bar. With phased installation of equipment, it is important to keep several things in mind:
· Any phased commissioning process that requires starting up and operating a system prior to construction and commissioning of one or more of its supporting utility systems places the project at greater risk for problems. The team should recognize that they are increasing their exposure and fully evaluate the potential outcomes.
· If an air handling system is started up and placed in operation prior to the completion of one of its supporting subsystems, then it will typically be necessary to repeat a portion of the air handling system’s functional test after the start-up and commissioning of the untested subsystem is complete. Retesting will add time and cost to the commissioning process and will often create a disruption in service. These items need to be anticipated and accounted for in the commissioning plan and budget.
· Some portions of the air handling system’s functional test plan may be skipped or deferred at the time of initial start-up due to the phased installation approach. When these portions are deferred, the door is opened for simply never performing that part of the test for a variety of reasons including oversight, difficulties scheduling an appropriate test window for an operational system, and difficulties in reconvening the test team. If these test steps are permanently deferred, then any operating deficiencies will either persist in an undetected state, often wasting energy or other resources, or manifest themselves as an operational issue.
In addition to coordinating air handling system testing with the testing and start-up of its supporting utility and subsystems, there may be specific procedures from the manufacturer that must be followed during the initial hours of operation if the functional integrity of the air handling equipment is to be ensured. Finally, the test plan will typically have a hierarchical structure, as discussed in Section 5 Testing Hierarchy. The successful testing of the entire system will be dependent on the successful completion of subsystem testing, which, in turn, will be dependent on the successful testing of the individual components. The following sections will discuss these topics in greater detail.
Prior to starting up and functionally testing the air handling equipment, all components of the electrical distribution system required for the operation of the air handling system need to be verified, started up, and tested to the extent necessary to support the safe operation of the air handling equipment. This testing should include all primary and secondary distribution and supply equipment, including the control system.
At first glance, this may seem obvious because the electrical motors that power the air handling system simply won’t work without voltage supplied to their terminals. However, just because voltage is available to the motor’s terminals does not necessarily mean the electrical system is ready to support the sustained operation of the motor. In general, the following items should be complete:
· Programming and manufacturer’s start-up procedures for the motor starters and variable speed drives
· Motor overloads should be selected and set to match the requirements of the motors
· All wiring connections should have been checked for security and proper connection points.
· Phase rotation should have been checked and adjusted as required to assure the proper direction of rotation for the air handling system motors.
The cooling and refrigeration systems associated with the air handler to be functionally tested needs to allow the system to meet the cooling and dehumidification requirements mechanically if it cannot meet the requirements using outdoor air. Operating the air handling system without mechanical refrigeration when it is required can result in loss of environmental control and may result in damage to the system and building envelope.
The cooling and refrigeration system readiness deserves careful consideration well in advance of the air handling system start-up because addressing and resolving issues can be time consuming. For instance, on a fast-paced construction project, it is not unusual for the start-up team to begin operating and functionally testing the refrigeration equipment prior to insulation of the distribution-piping network. This method allows the refrigeration equipment to be commissioned so that the air handling commissioning can begin. If the refrigeration equipment commissioning occurs during the summer months when ambient humidity levels are high, then condensation will occur on the distribution piping. The condensation can cause the following problems:
· Water damage to the building envelope and finishes due to condensation dripping off of the uninsulated piping This damage can lead to other delays and contractual problems because the damaged finishes need to be repaired prior to acceptance by the Owner at the contractor’s cost.
· Building structural degradation or indoor air quality problems Uninsulated lines may be located out of sight in vertical shafts or insulated walls. The condensation that occurs on the lines may be light enough that it can be absorbed by the surrounding building finishes without causing water damage. Or, the visible indication of the condensation problem may be remote enough to evade detection. The accumulated moisture can corrode building structural elements and piping, leading to future maintenance problems. If insulation and building materials located in the immediate vicinity of the piping absorb this moisture, they will provide an ideal environment for the growth of mold and mildew.
· Damage to the pipe insulation itself if the insulation is installed over the wet lines Water that is trapped inside the insulation, and its vapor seals, corrodes insulated piping and equipment. If the integrity of the vapor seals is not good, then water will migrate from the humid ambient environment through the exposed, non-vapor sealed insulation surfaces. This moisture will condense in the insulation and lead to corroded piping and the ultimate failure of the insulation system. In a hot and humid environment, it is not uncommon to find the insulation on a chilled water line to be totally saturated 15 to 20 feet upstream of an exposed, non-vapor sealed insulation surface.
· Scheduling problems Once the cooling systems are started up and operational, there is considerable pressure on the project team to keep them operational to allow the air handling systems they support to be started up and tested. Shutting down the system to allow the piping to dry off so that it can be properly insulated is undesirable, which paves the way for the problems associated with installing insulation over wet piping.
If condensation issues are brought up for discussion early in the project, they are often dismissed as minor annoyances that probably will not occur if schedule is maintained. However, if these issues become field problems, the pressure to complete the building on time can make it nearly impossible to resolve them in a satisfactory manner. Thus, it is probably better to raise the issue early and “plant the seed” for discussion at a later date.
Readiness requirements associated with the central heating equipment are similar to those discussed in the preceding paragraph for the cooling and refrigeration systems. If there is a heating load on the air handling system, then the heating system and its associated fuel supply system needs to be verified, started up, and tested to the extent necessary to support the safe operation of the air handling equipment. Operating an air handling unit without a functional heat source when the freezing is possible can cause significant damage to the unit. During functional testing, systems with reheat need a functional heating supply to maintain comfort conditions in the occupied zone, even if the heating system operation would not be required by the current seasonal conditions.
The coordinated start-up of the heating system relative to the start-up of the air handling systems it serves is an issue that needs to be considered early on in the planning process.
A fully functional and robust control system is critical for the successful functional testing of the air handling equipment. The control hardware directly related to the system to be tested must be fully commissioned prior to the functional testing of the air handling system. At a minimum, the necessary programming and physical hardware that allows the air handling system to execute its full control sequence must be in place, calibrated, and verified (actuators stroked, point to point wiring checked, etc.). In some cases, the communications network may also be required.
Many functional testing procedures involve pushing the systems to their design and operational limits which, to some extent, places the system at risk. For example, testing the mixed air low limit software on an economizer equipped system may involve lowering the discharge temperature set point below the mixed air low limit set point and observing the results on a cold day. Ideally in this situation, the mixed air low limit software should take over and prevent the temperature in the mixed air plenum from dropping to the point where the freezestat trips. But, if there is a problem with the software, then this test sequence will place the system at risk for damage due to the introduction of freezing air. Since the freezestat is intended to protect the system from this occurrence, it is important that the freezestat is fully tested and known to be operating satisfactorily prior to performing the functional test on the mixed air low limit software.
As a general rule, hardware safeties and interlocks that prevent damage to the equipment, system or building in the event of a failure must be commissioned and fully functional prior to performing the functional testing of the system they serve. Examples of this type of safety include freezestats, permissive start circuits, pressure relief doors, and duct static pressure safety switches. The installation of these components is discussed in the Control System Design Guide Chapter 3, Section 3.4.1.
As with the other prerequisites, coordinating the commissioning of the control system with the overall commissioning of the air handling system deserves some advanced planning supplemented by careful monitoring during the construction process. Control contractors (and commissioning providers) often find themselves in a tough situation because the completion of their work is highly dependent on the completion of the work of the other parties involved in the construction process (see the discussion in the Control System Design Guide, Section 2.2.2 The Contractor’s Requirements and Challenges). The commissioning provider needs to carefully monitor the progress of the control work in relationship to the other work on the project, the proposed schedule, and the time available prior to functional testing. If there is significant delay in work required for the control and commissioning work to proceed, there should be reasonable delay in the completion date for the control system and commissioning work. If not, then the issue needs to be brought to the attention of the project team for resolution as soon as possible.
As was the case for the other subsystems, the details of these requirements associated with commissioning the control system are beyond the scope of this guide. But, due to the crucial nature of the control system to successful air handling system operation, control-related topics are included in just about every chapter of the Guide.
Functional control system graphics are desirable, but may not be necessary to accomplish the functional test. If the system graphics are available, they can aid in observing the functional test progress and results. In addition, the features associated with the graphics can be functionally tested at the same time as the air handling system
If the system graphics are not available for the functional test, a separate functional test will need to be executed to verify these graphic features at a later date. The following graphic capabilities should be verified but may not affect functional testing of the air handling system:
1 Graphic response to alarms.
2 Graphic nesting; i.e. the ability to get to a related graphic by a direct link from a current graphic.
3 Graphic dynamics and response time to real data.
The test writer will need to determine the level of graphic functionality required for the air handling system functional test.
Trending capabilities for air handling unit functional testing is desirable but may not be necessary. System trending can provide valuable documentation and a second set of eyes and hands during a functional test. However, it is possible to structure tests or use data loggers in a manner that makes the trending capabilities unnecessary for functional testing.
In addition to start-up, trends are required for ongoing operation, warranty phase commissioning, and continuous commissioning functions. Thus it is imperative that the commissioning provider spends some time during the design phase commissioning process to ensure that the automation system structure and performance characteristics specified will support the required trending functions for the project. This is discussed in greater detail in. This design phase work should be supplemented by functional testing to ensure that the targeted trend capability goals have been achieved in the field.
If the trending capabilities will be used for the functional testing of the air handling system, then the functional testing of the trending system will need to occur prior to that of the air handling system. On the other hand, if the trending and monitoring requirements for the air handling unit will be handled in other ways (i.e., data loggers), then the functional testing of the trending capability can be deferred until after air handling unit testing.
The following items may need to be verified, but may not affect functional testing of the air handling system:
1 Point lists for continuous trending.
2 System response times under fully implemented trending.
3 Trend data archiving.
The test writer will need to determine the level of trending functionality required for the air handling system functional test they are writing and modify the prerequisites list appropriately.
Many air handling systems provide life safety functions in a coordinated effort with the Fire Alarm and/or Smoke Control System. If the operation of these systems must be integrated with the operation of the air handling system, then these systems must be available, verified, and fully functional to allow the integrated operation with the air handling system to proceed.
Integrating the operation of the life safety systems with the operation of the air handling system can be a complex task involving the coordination and interaction of just about every trade involved in the project. (Seefor additional discussion on this topic.) A commissioning provider can bring significant value to the project as well by making sure the commissioning plan coordinates the start-up and commissioning of these functions and allows sufficient time for the process to occur prior to the functional testing of the air handling system.