No Balance in Boilerplating HVAC Systems Testing
Logically, an HVAC system would be the core around which a building is constructed. In reality, the M/E engineer has to fit the system into the space he's given, with chillers, heaters, diffusers and ductwork limited to standard measurements. And since no system can be perfectly designed or installed for a given environment, testing, adjusting and balancing (TAB) are required to ensure that sys...
Logically, an HVAC system would be the core around which a building is constructed.
In reality, the M/E engineer has to fit the system into the space he's given, with chillers, heaters, diffusers and ductwork limited to standard measurements. And since no system can be perfectly designed or installed for a given environment, testing, adjusting and balancing (TAB) are required to ensure that system performance is correctly synchronized to the load.
However, like most processes in the A/E/C world, balancing isn't cut and dry, and those in the TAB business have some friendly advice for HVAC engineers.
According to Jerry Kettler, P.E., president of AIR Engineering and Testing, Dallas, a good understanding of the specified HVAC equipment is crucial. The designer should have a grasp of equipment size and its performance and limitations in full- and part-load conditions, as well as a recognition that certain equipment might work in one climate but not in another.
Kettler also warns to look closely at testing and balancing specifications, which are often boilerplated. Many times, the specs call for more than needs to be done. For example, a spec calling for two days' worth of temperature testing adds a lot of extra cost and time when two hours would suffice.
Perhaps Kettler's most important recommendation is to get to know the balancer and make that technician a part of the team. The balancer, he stresses, is a valuable resource and should be used as such. However, it's good to make sure the balancer is independent of the designer, contractor and supplier so he or she can do their job objectively. "A good agency will balance every project the same way, regardless of who you're working for," Kettler explains. "I tell my people we are working for the building, regardless of who is paying the tab. Our job is to be sure the building works."
When choosing a balancer, John Hamilton, assistant director of certification for the Testing Adjusting and Balancing Bureau (TABB), Alexandria, Va., stresses the importance of the balancer's integrity. One thing to look for is accreditation. Also, be suspicious of perfect balancing reports; they might be hiding small problems that can turn into big lawsuits down the line.
Another of Hamilton's recommendations is to conduct ongoing testing of systems, especially with the prevalence of mold and indoor air quality issues. "Most HVAC systems are put in, and they're never looked at unless there is a problem," he says. "It's like letting your teeth go until you're ready to pull one." Besides making sure that the system and equipment are running as they should, the reports from these "tune-ups" can come in handy should someone question a building's or system's integrity.
A final note from Kettler: as building systems continue to become more complex due to automation, the balancer's role becomes more critical—all the more reason to follow this friendly advice.
Tips for balancing HVAC systems
Have a good understanding of the HVAC equipment to be specified
Make sure balancing specs meet your needs
Make your balancer a part of the team
Conduct ongoing system testing
Don't accept "perfect" balancing reports