Everything You Need to Know About Air in Your Chiller's Coils

13 March 2017
 Categories: , Articles

Though air is vital for human systems, it is often fatal for HVAC systems, including chillers. As a non-condensable material, the presence of air within a chiller system can dramatically inhibit its ability to function efficiently; at the same time, it will cause stress across numerous parts.

Here's a quick overview of everything that you need to know.  

How Does Air Enter a Chiller System?

There are two main ways that air can infiltrate a cooling system.

  • Leaks: If a leak develops on the lower side of a chiller's oil system, refrigerant will slowly drain away. When this continues without any refrigerant being replaced, the suction can pull air into the system. When refrigerant is replaced without addressing the fact that air is being pulled in, the cycle will simply repeat itself.
  • Poor Service: If the cooling system is purged in a hurry or without expert supervision, the hoses may not have all their air expelled. Alternatively, the system may not be totally degassed after it has been opened in order to conduct repairs or replace a faulty component.

Why Does Air in the System Reduce Efficiency?

If you don't think having a little bit of air in your chiller's condenser coils is anything to worry about, think again.

Firstly, non-condensable materials entering the coils can significantly impair their efficiency. The science behind this is unquestionable, with sources indicating that non-condensable materials can reduce the efficiency of a chiller by up to 4% at 60% load and 7% at 100% load. Given the amount of energy that commercial chiller systems consume, it shouldn't come as a surprise to learn that a 7% reduction in efficiency can seriously stack up when it comes to monthly bills.

The main reason why this occurs is simple enough to understand: Condenser coil space is used to condense refrigerants. If anything invades the system that cannot be condensed, such as air, it takes up space. This means that the refrigerants cannot reach that space. Heat will not be diffused as effectively since there will be less surface area for the refrigerant to use; additionally, air is a very good insulator. The only thing the system will be able to do is increase the temperature and pressure of the refrigerant, and this will consume more energy.

Why Does Air in the System Damage Your Chiller?

Given the immense costs that can slowly result from an inefficient chiller, you should already have reason enough to ensure that air never invades the system. However, damage can occur that will eventually lead to a full breakdown, and that's largely down to the increase in coil pressure mentioned above.

With the pressure becoming higher and higher, other components will be put under far more strain than they are meant to handle. More pressure will be placed on gaskets, seals, and bearings. The motor will need to work harder. The compressor valves will be put under additional pressure, and that pressure will help break down lubricating oils.

Beyond pressure, the presence of air in your system can be problematic since the elements in air can react with moisture found in refrigerant. When heated under the right conditions, acidic elements will be formed. These will cause corrosion across numerous key parts, including the compressor and motor.  

What Should You Do If Air is in Your Chiller?

There are some online guides available telling you how to manually purge your system of air. However, manual purging will often remove a lot of expensive refrigerant, and you might fail to address the underlying problem. If there is air in your chiller system, make sure you have the system inspected and repaired by a professional from a company like Maximus Chillers.