Air conditioning airflow - How and why it is important
March 13, 2018
Essentially, your air conditioner will produce a set quantity of air as designed when manufactured. This air quantity differs on the size of unit and the fan speeds but generally the larger the unit, the more air is produced. This air is conditioned, either hot or cold, and travels through ductwork to condition your home or business premises. Air quantity is usually measured in Litres Per Second as it exits the air conditioning vents. A common way to measure this is with the use of a Balometer. This is a hood that covers the entire vent and can measure the airflow in or out in Litres per Second also referred to as l/s. HVAC systems depend on ventilation to cool and heat indoor environments. Moderate fluctuations in airflow and velocity can hinder a HVAC system's efficiency, thereby increasing the costs associated with running such appliances
Balancing the amount of air from an air conditioning system is reasonably simple once you have accurate measures of airflow, in l/s, from each vent. The correct balance can be achieved in two ways; establish how many l/s is required per square metre and adjust each outlet to this OR establish how many l/s already present and then adjust the airflow evenly per square metre. This may sound confusing but put simply, first method works on a correctly calculated quantity of air for the space which is then evenly distributed (newer and correctly designed systems) and the second method calculates the existing airflow which is then evenly distributed (any system including older, incorrectly designed systems).
Hopefully I haven’t lost anyone yet…..
In new systems, adjustments can be made through a zone controller, eliminating the need to gain access to the roof. This is only relatively new and requires some technical setup during installation.
Air Flow Measurement tools
At SEQAS Air and Electrical we use a Testo 420 Volume flow hood. This flow hood has served us well over the last few years and is a key piece of equipment when accurately measuring airflow. This equipment is distributed within Australia by Provo Instrumentation.
This will require some form of air flow measurement device such as a Flow Hood/Balometer. We use theTesto 420 Volume flow hood when measuring and calculating air flow: