Air Cooled Chillers Explained

Air cooled scroll chillers are very effective in function and price for small tonnage applications. 

Small single compressor process chillers managing a small cooling loop for manufacturing test equipment as an example. 

You can also point to a single ODU of a VRF chiller as a small air cooled package. 

Yes these VRF chillers are just air cooled scroll chillers. 

On the larger scales there will be two circuits with multiple compressors. 

The compressors will stage on or off as needed to make chilled water setpoint. 

You will see less variable speed or advanced scroll compressors in these systems due to cost.

These advanced options cost more and begin to push pricing to close to going with a screw chiller. 

Scrolls are a very popular option for modular systems that can stack to make larger capacities to fit the application. 

Scroll chillers make amazing entry level equipment to learn on. 

By their fit in the market they are very simple and have many parallels to other systems like RTU’s. 

This makes applying your experience much easier with confidence. 

The major things that will complicate them is the controls are more advanced than most standard equipment and we have an hydronic evaporator. 

Everything else like the condenser coils, fans, lineset, EXV, and drier are very comparable. 

Even the compressor staging mirrors how a RTU would stage to control supply air temp. 

You can compare leaving water temp to your supply air temp. 

It’s a hydronic evap vs air over. 

One term that will need to become a part of your vocabulary is evap Approach. 

Approach = leaving water temp - evap saturation temp 

Most evaps on scroll chillers will be a 8-10F approach with a full load. 

This will include braze plate, DX shell & tube, and tube in tube.

MTT

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