Having an air separator in your HVAC system greatly affects the system’s overall performance, especially in a chilled-water system. While air elimination is important in any ventilation setting, it is more important in the chilled-water system than in a hot-water system because the cold-water unit can hold more air inside the tank.

Air separation is a common term when discussing HVAC equipment. There is a wide variety of Air Separators, and there are several uses depending on your needs.

While Dissolved Air Flotation (DAF) is necessary even in a ventilation system with manual vents, it is still very important to consider having an air separator because no hydronic system is airtight. Otherwise, the constant air/water mixture being pumped will dramatically decrease heat transfer efficiencies. A proper air separator also decreases oxygen exposure which is important because oxygen causes a large amount of corrosion that will contaminate the system.

What are the HVAC Air Separator options?

Some options for air separation units are:

  • Tangential Air Separators
  • In-Line Air Separators
  • Sediment-Removal Separators
  • Air & Dirt Separators
  • Air Purgers or Air Scoops

Along with the outlined air separators, there are also options available for these units such as:

  • Strainer
  • Less Strainer
  • MG – Magnetic Options

If you are interested in a more customized solution, please reach out to us regarding custom fabrication.

How do these Air Separators work?

Each air separator has its own method for air elimination. Below, we describe the outlined options listed above.

Tangential Air Separators

Tangential Air Separators 

The Tangential Air Separator design provides air-free fluid flow which protects against damage and system noise. This unit features grooved or flanged inlet and outlet connections. The tangential design results in a smaller unit. There are higher-working pressures available for this air separator.

In-line Air Separators 

Our In-line Air Separators series offers a lower-cost alternative for air separation in hydronic heating and cooling systems. The IAS/IASS series becomes a point of lower system velocity by changing the direction of flow through the device.

This lower velocity along with the change in direction allows air molecules to separate from water. Once the separation occurs, the air rises within the inline air separator. Then, it is discharged through the vent opening at the top of the vessel. This will go to either the atmosphere or an expansion tank.


In Line Air Separator Sediment Removal Separators

Sediment Removal Separators 

The Sediment Removal Separator (SRS) is a centrifugal-type sediment removal. While the design is similar to the TAS Series Air Separator, the SRS also offers the advantage of solids removal.

The tangential design allows for sediment removal through the vortex action, which forces suspended sediment to the outside of the vessel and into the bottom sump. You can then easily remove the sediment. The tangential action also creates a vortex that forces entrained air into the center and removes it through the top opening. It is then released into the atmosphere or sent to an expansion tank.

Air & Dirt Separators

The High-Velocity and STAD Standard Velocity Coalescing Air & Dirt Separator is intended for use on commercial HVAC, institutional, and industrial applications to remove entrained air and particulate from system water. This is accomplished by the use of a High-Performance saddle ring coalescing assembly internal to the separator. 

Air Dirt Separators Air Purgers Scoops

Air Purgers (Air Scoops)

The Air Purger or Air Scoop operates on the premise that air rises in the piping and then into the unit. It is directed to the top opening and out of the system through an air vent or to an expansion tank. Since the proper operation of this type of air separator is also dependent on velocity, sizing this type of air separator is a function of proper flow rate. This type of air separation is best suited for residential and light commercial applications.

How to determine Air Elimination Efficiency

Air Elimination efficiency chart

Need Assistance?

There are plenty of model options available at American Wheatley HVAC. If you are uncertain which of these models will work best for you or need more customization, please reach out to us. We are eager and ready to help you find the right solution for your needs! 


* Our American Wheatley HVAC Brand Air Separators are constructed and stamped according to ASME Section VIII Boiler and Pressure Vessel Code requirements and National Board registered.