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.
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 start up technician or engineer and the test and balance crew. During start up the boiler start up technician should test and verify the proper function of the boiler per manufacturers specifications. During and after the start up the technician should generate a report of all start up work done including adjustments, calibrations, and test data collected during the start up. 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.
After the start up and test and balance is complete and all final reports are received from the start up and test and balance crews then the Cx tech can perform a thorough functional test of the boiler or boiler system. The following are not all inclusive to 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 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.
- 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.
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 lock outs, 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. Lock outs and reset schedules in the BAS and otherwise needs to be taken into consideration before functional testing. Once all the basics are checked the next step is physical testing as follows:
- Start all 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 speed drives ramp pump up to maximum operating and back down to minimum speed and check for vibrations and unusual noises.
- Check all valve actuation for supply, return and any bypass valves.
- 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 boiler is a modulating boiler run boiler as minimum, maximum and various stages and verify no unusual noises or vibrations.
- On shut down after basic testing ensure proper shut down sequence of the boiler.
- Start boiler and shut off 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 back flow preventer. Ensure no water is leaking from the device.
- 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.
The test is not all inclusive as the functional test script must be generated and tailored using the mechanical drawings, equipment schedules, project and equipment specifications along with the owner requirements.
If you are in need of commissioning services or written scripts contact High Performance HVAC using our contact page.