This checklist identifies Key Commissioning Test Requirements and Key Preparations and Cautions for testing boiler systems. When writing a test, use this checklist to help ensure that these key areas have been covered. The buttons following the checklist items link to supporting information within the Functional Testing Guide and the Control System Design Guide.
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This checklist focuses on hot water boilers. Many of the items are also applicable to steam boilers and systems, particularly steam boilers that provide hot water through a converter. However, the unique requirements and cautions for steam boilers and systems are not addressed.
Key Commissioning Test Requirements
- ___ 1. During design review, the following items were addressed to avoid issues during functional testing:
- a) Time delay between boiler start/stop commands are per design.
- b) The primary/feed water pump operation time delay after the boiler is commanded OFF is per design.
- c) The reset parameters are optimized for the system. In addition, ensure the reset control strategy does not result in a return water temperature from the building loads that can cause the flue gases to condense in non-condensing boiler systems.
- ___ 2. The following "prefunctional" checks were completed and verified prior to performing a functional test (note that this is not a comprehensive list of all prefunctional checks):
- a) All safeties, interlocks, and alarms operate correctly in both automatic and manual operating modes.
- b) Sensor installation and calibration is verified.
- c) Automatic isolation valves are installed and operate correctly, if applicable. Automatic isolation valves are typically installed when multiple boilers are connected to a common supply header. Boilers with dedicated pumps generally do not have automatic isolation valves.
- ___ 3. Proper boiler staging is verified under normal operation, as well as all failure and emergency operating modes.
- ___ 4. Boilers and primary feed/water pumps stage up and down per the sequence of operations under all operating modes.
- ___ 5. Automatic isolation valve(s) associated with the respective equipment opens fully upon start-up and closes fully upon shutdown after the specified time delay has expired.
- ___ 6. The system maintains hot water supply temperature setpoint under all operating modes, including automatic, manual, and failure/emergency modes.
- ___ 7. Proper coordination between individual setpoints and reset strategies is verified. For example the hot water temperature reset and air handling unit discharge air temperature reset control strategies are compatible.
- ___ 8. Control algorithms generate the proper water temperature setpoint based on the reset parameters specified in the sequence of operations.
- ___ 9. The O2 trim controls, if applicable for a specific project, operate to ensure that excess oxygen in flue gas is maintained at setpoint. If O2 trim controls are not installed, review flue gas report and verify the boiler was tuned at high-fire and at least one intermediate part-load operating point.
- ___ 10. All control loops stabilize within a reasonable amount of time (typically 2 to 5 minutes) after a significant load change such as start-up,or automatic/manual recovery from shut-down.
- ___ 11. Some projects may require full-load capacity and part-load turndown performance testing. Tests should be performed when the loads generated can be dissipated adequately. Verify the boiler meets the manufacturer’s stated part and full load performance under actual operating conditions.
Key Preparations and Cautions
- 1. Prefunctional checklists should be completed throughout construction and during normal commissioning site visits as installation of the various components and systems are completed. Sensor and actuator calibration, control point checkout, and boiler/piping flushing is typically considered to be part of the construction prefunctional checklist.
- 2. In addition to the prefunctional checklists, all manufacturer-required component start-up procedures must be complete in order to conduct functional test procedures. Local codes should also be reviewed to ensure any required start-up and testing procedures are performed prior to long-term system operation. Both the air-side and water-side TAB must also be complete prior to functional testing.
- 3. Safety and interlock tests, as well as some test procedures and loop tuning efforts (for example, high limit cut-out set points, emergency shut-down procedures, and failure/back-up system operation) could place the system at risk if the sequences do not function as intended. Appropriate precautions and procedures should be in place to protect personnel and machinery. These should include plans for quickly aborting the test if necessary.
- 4. At a minimum, the construction prefunctional checklist should be completed on the components/systems served by the boilers, and they should be capable of safe, temporary operation. Final boiler system testing should not be performed until all of the associated systems are fully operational, including chemical treatment and make-up water controls, if applicable. Final boiler system testing can be best achieved through trending under normal operation.
- 5. Ideally, functional performance testing, including capacity testing if required, would occur during the heating season, so that the entire system can be observed under normal operating conditions without seriously overheating the building. Construction work in the building could be adversely affected if the space temperature deviates significantly from a tolerable level.
- 6. Valve leakage tests and tests that are targeted at verifying valve stroke, spring range, and sequencing should be conducted with the pumping system operating at its peak differential pressure.
- 7. All resets except the one being tested should be overridden to prevent unwanted system interaction during testing. Once each reset control strategy has been verified independently, the remaining resets should be reinstated. System operation must then be monitored to ensure all control processes remain stable. This verification is best accomplished through trending under normal operation.
- 8. Integration of temperature setpoints must be coordinated between the boiler and equipment served. This is best illustrated through the following example. The water temperature setpoint is reset to 120°F, but the discharge air temperature setpoint for an air handling unit is reset to 130°F under the same operating conditions. The hot water coil control valve will modulate wide open because the AHU will never meet a 130°F setpoint with 120°F water, This scenario can result in excess water being pumped through the system, and possibly even bringing more boilers on-line to meet a load that does not exist.
- 9. Coordination between hot water temperature and coil design should also be checked. It is possible that the air temperature coming off the coil may not meet setpoint due to design limitations of the coil itself. Preferably, this issue is addressed during design-phase commissioning.
- 10. If the hot water temperature reset strategy is tested when there is minimal to no heating load, make sure to test the low end of the reset (coldest hot water supply temperature) first in order to minimize test time. It is easier and faster to add heat to the loop rather than to try and take it out when there is little load on the system.
- 11. If the boiler system is tested during off-peak months, ensure that the spaces served by the respective air distribution systems (air handling and terminal units) do not exceed safe temperatures. Often systems will be tested while construction is still being completed in the spaces being served. Elevating space temperatures well above ambient conditions may cause discomfort or create unsafe working conditions.
Page last updated: September 11, 2006