HVAC test and balance ensures your facility is operating as efficiently as possible. Balancing measures the distribution of heated and cooled air to ensure you’re getting the most from your HVAC equipment. This minimizes energy use, maintenance costs and humidity levels. Testing and balance ensures the entire system is operating at full-capacity.

HVAC testing and balancing (TAB or air balance) is the process of ensuring that your heating, ventilation and air conditioning system is operating properly and delivering the correct air quantities at the air devices inside your building. This involves cycling the equipment on to verify functionality, measuring preliminary airflows, checking fan rotations, adjusting fan speeds, adjusting dampers and measuring final airflows to ensure conformance to design.

 

HVAC Testing, Adjusting and Balancing (TAB) are the three major steps used to achieve proper operation of HVAC (heating, ventilation, and air conditioning) systems. TAB usually refers to commercial building construction and the specialized contractors who employ personnel that perform this service.

In general, the TAB specialist performs air and hydronic measurements on the HVAC systems and adjusts the flows as required to achieve optimum performance of the building environmental equipment. The balancing is usually based upon the design flow values required by the Mechanical Engineer for the project, and the TAB contractor submits a written report which summarizes the testing and balancing and notes any deficiencies found during the TAB work. Many times facility managers will use a TAB contractor to assist in identifying preexisting or common issues with a facility. While not necessary to be a TAB contractor, many contractors tend to hold professional air balancing certifications.

Testing

Testing is the use of specialized and calibrated instruments to measure temperatures, pressures, rotational speeds, electrical characteristics, velocities, and air and water quantities for an evaluation of equipment and system performance.

Balancing

Balancing is the methodical regulation of system fluid flows (air or water) through the use of acceptable procedures to achieve the desired or specified design airflow or water flow. When beginning the balance of a system, you must locate the terminal with the least amount of flow in regards to the engineer’s drawing. Once the “low” terminal has been located, you can then proceed to adjust all other diffusers/grilles (air) or circuit balancing valves (water) to proportionally match the original “low” terminal. There must be at least one terminal that is wide open to achieve optimum efficiency.

Adjusting

Adjusting is the final setting of balancing devices such as dampers and valves, adjusting fan speeds and pump impeller sizes, in addition to automatic control devices such as thermostats and pressure controllers to achieve maximum specified system performance and efficiency during normal operation.

The proper function of a heating and cooling system requires more than simply installing the equipment and turning it on. By itself, a forced-air furnace, air conditioner or heat pump will provide heating and cooling, but indoor comfort will not be the best the equipment is capable of producing. The HVAC systemwill also function at a lower level of efficiency than it’s designed for, which means you’ll waste both energy and money. To ensure your heating and cooling systems are operating at their best, it’s necessary to perform testing, adjusting and balancing on your HVAC equipment.

What is testing, adjusting and balancing?
Testing, adjusting and balancing is the process of evaluating temperature and environmental control systems to ensure they’re heating or cooling according to design specifications and at the equipment’s best level of efficiency. The process involves using test instruments, sensors and monitors to verify proper temperatures, airflow and other characteristics of the HVAC system.

  • Testing: Testing establishes the quantitative aspects of the HVAC system, such as the volume of airflow that’s being produced or the heat transfer rate.
  • Adjusting: Adjusting makes changes and alterations to system components so that the heating or cooling unit is operating properly and according to design requirements and indoor comfort demands. Adjusting may involve changing temperature settings, opening or closing a damper, increasing or reducing fan or blower speeds or making other changes that affect system function.
  • Balancing: Balancing ensures that proportional airflow, heat transfer and other characteristics are equalized among all terminals, branches and subsystems. Balancing could involve making sure that equal amounts of heated air are distributed down two branches of a ductwork system.

Applications of testing, adjusting and balancing

  • New HVAC systems: When heating and cooling systems are installed in newly constructed buildings, they should be tested, adjusted and balanced as part of the commissioning process. This ensures that HVAC equipment will be working at its highest efficiency and performance level when the building is placed into operation. HVAC testing, adjusting and balancing in new construction also ensures that heating and cooling equipment provides the level of indoor comfort that designers, planners, owners and builders intended.
  • Existing HVAC systems: Over time, as heating and cooling systems work from season to season, their performance deteriorates. Testing, adjusting and balancing existing HVAC systems restores heating and cooling equipment to its best operating level, boosts system efficiency and significantly improves indoor comfort.

Ductwork is key
Ductwork is the air distribution network that brings heated and cooled air to your home’s interior. All of the heated and cooled air that’s produced by your heating and cooling equipment travels through the ductwork. This means that air leaks, unsealed connections, damaged sections or other problems in the ductwork can have a significant effect on indoor comfort and system efficiency. Before any testing, adjusting and balancing efforts are made, make sure the ductwork is in good condition, properly sealed and insulated where necessary. Otherwise, testing results will be incorrect and adjustments will be futile.

Testing, adjusting and balancing will address factors such as:

  • Airflow quantities from the HVAC unit
  • Amount of air flowing through the ductwork and exiting into the building from registers, vents and grilles
  • Pressure levels, including air velocity, barometric pressure, static pressure, differential pressure and total pressure
  • Mixture levels and temperatures of air in plenums
  • Air turbulence and stratification within the system
  • Fan and blower operation, including motor amperage and voltage
  • Fan speed and rotation
  • Proper operation and sequencing of automatic control systems