Boiler Commissioning & Functional Testing - Commissioning (Cx) any type of HVAC equipment is many different procedures from the beginning of the commissioning process to the end of the process. One of the most important procedures during the Cx process is functional testing. The functional testing always precedes the final testing where a test of all the combined equipment is done in an integrated systems testing. Once successful testing is completed and all discrepancies corrected a final commissioning report is generated including all the test data and information collected during the entire process of testing and commissioning.
This is simply a basic set of tests to be performed for boiler functional testing. Each system is different and will require a different tailored test based on equipment submittals, control program, and design documents. The prefunctional checklist should be complete before engaging in this test.
Boiler Commissioning & Functional Testing - Quality Assurance
Functional testing of a hot water boiler in the commissioning process can be streamlined if coordinated properly. Much of the Functional Testing Procedure can be accomplished by coordinating with the startup technician or engineer and the test and balance crew. During startup, the boiler start-up technician should test and verify the proper function of the boiler per manufacturers specifications. During and after the startup the technician should generate a report of all startup work done including adjustments, calibrations, and test data collected during the startup. The Cx Technician or Engineer can then verify first-hand essential data needed to complete the Functional Testing Procedure document. The same applies by coordinating with the Test and Balance crew.
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Boiler Commissioning & Functional Testing Basic Physical Overview
After the startup and test and balance is complete and all final reports are received from the startup and test and balance crews then the Cx tech can perform a thorough prefunctional and functional test of the boiler or boiler system. The following are not all inclusive of every boiler installation. The list should be tailored for each individual installation. Initial checks of the boiler should include:
- Equipment is clean and free of any physical damage including any debris inside of any control panels.
- All safety devices, including the pressure relief valve, have been tested and tagged according to local code and national requirements.
- All unit identification tags, piping labels, operating manuals, maintenance checklist, and basic documentation are with the boiler(s).
- All pipes have been flushed and strainers cleaned.
- Piping insulation and heat trace tape/controls (if equipped) are complete (especially for outside piping).
- Piping is properly labeled for identification per code and other requirements.
- All electrical connections are tight including all ground connections.
- All breakers for the boiler system including associated pumps are labeled properly for the source.
- Boiler drain is accessible and can be drained to a sanitary drain near the boiler drain.
- Actuators are installed and checked for proper travel to open and close valves. The actuator is securely mounted and connection to the valve is tight.
Quality Assurance - Boiler Commissioning & Functional Testing
If the boilers are controlled by a building automation system (BAS) ensure the BAS system is checked while performing the procedure. All program functions including alarms, program lockouts, and other BAS variables are checked and ready for testing. Temperature sensors need to be verified for proper installation and location according to representative graphics on the display monitor. All set points and rest schedules need to be verified including the outside air temperature device calibration. Lockouts and reset schedules in the BAS and otherwise need to be taken into consideration before functional testing. Once all the basics are checked the next step is physical testing as follows:
- Start all circulator pumps individually. Check for any noises and for unusual vibrations originating with the pumps individually running and all running at one time. If the pumps are controlled by any variable speed drives ramp pump up to maximum operating speed and back down to minimum speed and check for vibrations and unusual noises.
- Check all water loop valve actuation for supply, return and any bypass valves.
- Test pressure loop sensor.
- Test all automatic dampers for combustion air, ventilation and exhaust dampers for proper operation before starting boiler.
- Reset all pumps and valves for normal automatic operation and fire the boiler. For dual fuel systems test both different fuel types. Again check for any unusual vibrations and noises. If the boiler is a modulating boiler run boiler as the minimum, maximum and various stages and verify no unusual noises or vibrations.
- On shut down after basic testing ensures proper shutdown sequence of the boiler.
- Start boiler and shut off the pump. Ensure boiler shuts down based on loss of flow. This should be indicated as an alarm with the BAS. After successful testing is complete restore all settings to normal.
- Test the high limit setting on the boiler by lowering the temperature setting on the high limit control. Check that boiler shuts down and that the BAS system indicates an alarm.
- Test the low water cut-off by disconnecting the wire to the low water cut-off. Ensure the boiler shuts down and all alarms are indicated at the BAS.
- Test any safety controls including safety switches such as temperature limit switches.
- Check backflow preventer. Ensure no water is leaking from the device. Most backflow preventers require annual inspections and certification. Ensure the device has been properly inspected and certified. Sometimes, this is done by an outside third-party contractor.
- Test valves and actuator functions for valves. Valves not set properly will have a leak rate. Additionally, valves need to be tested when pumps are on at full capacity to ensure valves do seat properly and there is no leakage because of pressure in the system from pump operation.
- Check pressure reducer valve for proper pressure and no leaks.
- Check make-up water supply to ensure reliability.
- Test the boiler pressure relief valve by lifting the test gate. Ensure water drains from pressure relief valve.
- Ensure all PID loops on BAS have been calibrated or tuned to prevent erratic modulation and proper control.
Boiler Commissioning & Functional Testing | Additional Factors/Checks of the System
- Seismic code considerations in geographical areas where this is applicable.
- Pressure/temperature plug checks if any part of the system is so equipped.
- Visible water leaks after boiler system has cooled or while in operation
- Expansion Tank checks/functions
- Air management/elimination components checks/functions
- Primary combustion air factors? Are there dampers that automatically open before boilers fire? If so, are they interlocked to prevent boiler firing if they are closed?
- Water treatment system checks
- Automatic air vents on risers?
- All boiler safeties tested for proper functionality?
Again, this is not all inclusive of all the checks that need to be performed on all systems as each system has its own unique requirements. This is an attempt to be thorough from the systems I have commissioned previously.
Boiler Commissioning & Functional Testing - Quality Assurance – Conclusion
The test is not all-inclusive, the functional test script must be generated and tailored using the mechanical drawings, equipment schedules, project and equipment specifications along with the owner requirements. A successful Boiler Commissioning & Functional Testing procedure will depend on many people including the commissioning team, the owner, the contractors involved, and sometimes the general contractor.
Boiler Commissioning & Functional Testing - Quality Assurance
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Boiler Commissioning & Functional Testing | Writer
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