To be truly successful in the commissioning arena, it is essential to understand the background behind how the system will respond to a test as well as what could be causing the observed responses.
To help commissioning providers gain this knowledge, the Functional Test Guide focuses on the fundamentals behind testing. Functional tests are supplemented with information that will allow the commissioning provider to improve their ability to find and correct deficiencies in a cost effective way. Additionally, understanding the physical principles behind the HVAC process under test will be helpful in developing a test procedure that truly verifies the process.
One of the primary purposes behind commissioning a system is to ensure that it functions according to its design intent. If it doesn’t, the commissioning provider often identifies the problem that is preventing intended operation. Since we are dealing with machines assembled by humans in a real world (usually under a lot of stress), it is a near certainty that there will be some problems identified by the commissioning process, even on the most well designed, well-implemented project.
If you (as the commissioning provider) have identified a deficiency, then you probably will need to become proactive in correcting it. When a problem has been identified, it is fairly common that the test process is questioned. In other words, the system did not have a problem, it was the test routine that had a problem. If the test is well understood, and you are not just performing steps in a process, then you will gain the following benefits:
· Confidence that the test was done correctly and the observed deficiency is real. Without this confidence, you may be intimidated into doing extra work. This additional work would be in reaction to an accusation by the responsible party that the problem does not exist.
· An understanding of how the test result could be wrong. Knowing what you don’t know is extremely important. This perspective can be helpful when troubleshooting a problem with the other people involved in correcting it.
· The ability to discuss the facts. Handing out a trend graph that shows a picture of the deficiency can focus the discussion on the problem, instead of the people. The problem is with a machine, not another person or organization.
· An expanded knowledge base from which to draw. In the modern construction process, resolving commissioning problems is a lot like a tennis match. No matter how good you are, every time you hit the ball over the net, there is a chance that it will come back your way and you will have to deal with it again. The bigger your knowledge base is, the higher the likelihood that you’ll be able to easily and quickly “return the serve”.
“You can lead a horse to water but you can’t make him think.”
-Hospital Facility Director commenting on the actions of a mechanical contractor
who was core drilling holes over live 480 volt distribution gear with the buss bars exposed
Sometimes, having a complete understanding of the issues is still not enough and the consequences of the less enlightened actions of other parties will still need to be dealt with. The more you understand about the fundamentals associated with the systems, the better prepared you will be to deal with commissioning issues. Providing an understanding of the fundamentals behind air handling systems and how these fundamentals relate to functional testing is a goal of the educational component of the Functional Test Guide.
“Any sufficiently advanced technology is indistinguishable from magic.”
In some cases, one of the problems that must be faced is that we, as commissioning practitioners probably aren’t aware of what we don’t know. This problem is especially true when we are dealing with new technology for the first time or with a technology in a unusual application. For example, in moderate climates like San Francisco, coil freezing and freezestat problems are relatively rare. However, if one travels East towards the Sierra Nevada in California, these issues are quite common. Someone who has spent most of their career working along the coast may approach the problem of designing, starting up and commissioning their first system in the mountains in a manner similar to what they might use in the San Francisco Bay area, with frozen coils as a result.
While simple in concept, HVAC systems are actually complex applications of technology and physical principles that must function in a dynamic environment to meet the changing requirements of the loads and occupants they serve. The sheer volume of this Guide (including the Design Guide and Functional Test Guide) can be thought of as a statement of one of the current problems in the HVAC industry. We assemble prototypical systems that rely on sophisticated equipment and complex events to function properly, yet we expect these systems to work flawlessly with few modifications when they are first started up.