To maximise the removal of entrained air, a deaerator should be located where the system water is at its hottest, that is, in the flow after the boiler in a heating system or in the return before a chiller in chilled water system. It is also worth noting that to prevent air being drawn into a hydronic system and maintain low dissolved oxygen levels, it is important to maintain a sealed system at a positive pressure (at the pressurisation unit).
Deaerators or dirt air separators are used in hydronic systems to remove dissolved gases form the water. Passive deaerators have a matrix that stimulates the formation of small bubbles that coalesce and released through air vents. Dissolved air in heating and chilled water systems is a major contributing factor to system corrosion and the growth of certain bacteria. Trapped air in a system may also cause pump noise, inefficient operation of system pumps and issues with flow measurement during commissioning.
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