Balancing of Air Flow in HVAC System Components

hvac system components


Proper maintenance of the HVAC system of a building is impossible if proper balance of air flow is not insured in all occupied building zones or conditioned spaces. If the air flow in any part of the HVAC System is allowed to become unbalanced with respect to zone requirements, either too much or too little air flow, the occupants of the affected zone are likely to take action that can only result in premature or excessive collection of particulate matter and/ or serious damage to the equipment itself. These actions include taping over air supply or cold-air return grilles thought to be related to air flow problems, removal and loss of grilles or diffusers, abnormal thermostat settings causing excessive running of heating or cooling apparatus, overly frequent thermostat setting changes causing excessive start/stop cycling of heating or cooling apparatus, disabling of thermostats thought to be responsible for perceived lack of air flow balance, and blocking off of parts of the building creating new zones not allowed for in HVAC system design. These actions, taken by occupants in order to secure their own comfort, are usually the result of inadequate attention to air flow balance. All these actions will mean more frequent and costly cleaning and repair of affected HVAC system components.

Two Tips for HVAC System Components

Two things are needed to avoid these difficulties and insure proper balance of air flow in all occupied building zones or conditioned spaces: First, systematic monitoring of occupants and/ or spaces must be carried out. And second, at least one person per shift on the building engineering staff must be properly and completely trained in the specific air flow balancing techniques and equipment applicable to the HVAC system components of the building.

Monitoring of Occupants and Spaces

In smaller buildings, monitoring of occupants and spaces can be a simple matter of walking the various spaces of the building, noting temperature and other air quality characteristics of each space, and asking occupants, if any, to comment on their perceived level of comfort. In large buildings with many occupants, it may be necessary to adopt a more formal process, utilizing regular measurements of, logging of, and corrective action on temperature, humidity, particulate matter, or other air quality measurables connected to HVAC system air flow balance. Formal outside training may be necessary to assure one staff person on each shift capable of adjusting air flow balance throughout the building. This training can sometimes be obtained from the manufacturer of the HVAC system components affecting airflow balance. Some community colleges also provide courses which include training in specific air flow balance techniques and equipment. More frequently, such information is obtained by engineering staff members by careful study of equipment, blueprints, and engineering manuals supplied with HVAC system components at the time of installation. It is critical that this information, once reliably established, be documented and stored. If air flow balance techniques and equipment use are written down or stored electronically, training of new engineering staff members is greatly simplified and tends to produce a more uniform approach to air flow balance over time. Attention paid to air flow balance throughout the building HVAC system will pay for itself many times over in reduced cleaning and repair costs.


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