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Chiller Operator & Preliminary Checks

Chiller Startup Procedures: Chapter 1

Chiller Operator

Have you ever wondered how to become a chiller operator? In this module, we will help you to visualize the life of a chiller operator. By the end of this module, you should be able to: relate with the chiller operator’s role, and identify the qualities and certifications to become one. Skip to quiz!


Chiller operators’ life revolves around chillers. Some might say that this job is less exciting. Think again! Starting and stopping chillers is not the only thing they do.

Chillers are huge machines that can cool complete buildings. Chiller operators need to pay attention to every component. It is not as easy as switching an air conditioner by remote control. They must be skilled and knowledgeable to operate chillers effectively.

Nowadays, chillers have become common in almost every building and are one of the highest power-consuming units. Do you know: In many buildings, more than 50% of the electricity is only consumed by chillers.

Non-qualified operators have little knowledge about a chiller’s working. They use poor chiller startup procedures that may

  • prevent the chiller from running smoothly,

  • cause high power consumption, and

  • result in a hazardous situation.

Qualified Technician

Though chillers provide cooling, they can trouble us if operated wrongly. This is the reason a chiller operator’s role is a higher priority in any building.

The main qualities that companies look for in a chiller operator:

  • Certifications,

  • Familiarity with chiller,

  • Communication skills, and

  • Organizational skills.

Certifications granted by reputed organizations are better indicators of a technician’s competence. Certifications are usually granted after meeting well-defined criteria like

  • demonstrations of knowledge,

  • the passing of examinations, and

  • participation in professional or technical programs.

EPA 608 certification is mandatory to work on chillers. NATE certification is often preferred by companies. Some states or regions may have their own certifications required for chiller operators.

A chiller is like a solved puzzle that has come to shape after putting a lot of components together. Getting to know about each and every component is not necessary to chiller operators. But operators should have a basic understanding of all the major components and their primary functions.

If the operators are not familiar with the chiller, they will not be able to work around any equipment issues. Before operating the chiller, make sure that you know the functions and locations of all the chiller components.

Imagine that scale is formed on the condenser tubes of a chiller. You know that scaling on condenser tubes reduces chiller efficiency and needs to be cleaned. How will you explain this to a person who has no technical knowledge and get approval?

Chiller operators should be able to communicate with company management. A qualified technician knows how to explain what needs fixing without using many technical words.

Chiller operators should also know how to answer any follow-up questions. They should not confuse with answers.

To get jobs done quickly and effectively, it’s important that you have an organized chiller plant. This will allow to find the parts and tools you need quickly.

It is essential for chiller operators to stay organized while working. Keeping the chiller plant clean and organized helps to maintain safety and ensure accountability of parts. A qualified technician has organizational skills to ensure that all the parts and tools are available.

Before starting the chiller, we need to pay attention to every component of it. Efficient chiller startup procedures make the chiller run smoothly and decrease energy consumption. You shouldn’t attempt to operate any chiller unless you’re qualified for it.


Preliminary Checks

Qualified operators do preliminary checks before operating any chiller. You can’t be a qualified operator without knowing about preliminary checks. By the end of this module, you should be able to do the necessary preliminary checks for a chiller. Skip to quiz!


Before going for a ride on a bike, we check fuel, lights, engine oil condition and level, brakes, chain lube, etc. In the same way, we have to do preliminary checks before starting a chiller.

To ensure the efficient operation of a chiller and for our personnel's safety, we have to do preliminary checks. Preliminary checks are a simple and effective way to find malfunctions and hazards before starting a chiller.

General Cleanliness

General cleanliness of a chiller plant is very important. If a chiller plant is not clean, it can affect us in many ways. For example, dust in the surroundings can accumulate on chiller components, and walking on a wet floor can make us fall.

Chiller operators should walk around the chiller plant and visually inspect for cleanliness. They have to make sure that all the chiller components and surroundings are clean.


All the nuts and bolts of chiller systems should be tight. We need to check the tightness of all the bolted connections with wrenches.


To find leaks in the plumbing system in our homes, we check all the pipes for water traces. Similarly, we have to check all the pipelines of the chiller for water or oil traces to find leaks. We have to make sure that there are no leaks.


In chillers, evaporators and chilled water pipelines are insulated. Insulation creates a barrier between pipelines and outside air.

If there is any damage to insulation, moisture in the air becomes water vapor by passing over a cold surface. This can create wet surfaces and damage pipelines.


Recall that valves are devices used to decrease or stop the flow of fluids. Before starting a chiller, we’ve to make sure that all the inlet and outlet valves of the chiller are open. There are different types of valves used in chilled water systems. Let’s learn which way to turn to open them.

Ball valves and butterfly valves are quarter-turn valves. They are used for shut-off or isolation of a chilled water pipeline.

If the handle of a ball and butterfly valves are away from the pipe, they are in closed position. We have to turn the handle 90° in an anti-clockwise direction to open the valves. We need to make sure that the handle is pointing to the pipe.

Gate and globe valves are multi-turn valves. Gate valves are used for starting and stopping the flow. Globe valves are used to stop, start, and regulate flow.

Gate and globe valves are opened by turning the handwheel several times in the anti-clockwise direction. We shouldn’t turn the handwheel once the valve becomes fully opened. Otherwise, it can damage the valve threadings.


Strainers are used to filter the water flowing through a pipeline. They have wire mesh inside them that traps dirt from the water. These protect piping equipment from potential damage caused by dirt.

We’ve to open strainers and check whether the mesh is clean or not. If the mess is dirty, we need to clean and reassemble the strainer.


Compressor oil is used in the chiller’s compressor to lubricate its internal components during operation. One of the main factors of a well-functioning chiller’s compressor is having the right lubricant in the correct quantity.

During preliminary checks, we’ve to make sure that the compressor oil is within operating range. We need to observe the compressor oil level through the sight glass. The compressor oil should be in between the high-level line and the low-level line.

The quality of compressor oil is a significant factor that affects chiller performance. We have to check the quality of compressor oil through the sight glass.

Recall that compressor oil in chiller systems is very clear and transparent. Compressor oil will only become dark in color if it is exposed to

  • impurities, or

  • excessive temperatures on the discharge side of the compressor.

A chiller operator needs to observe the color of the compressor oil through the sight glass. If the compressor oil is dark in color, we should change it.

Cooling Tower

We find cooling towers in water-cooled chillers. Cooling towers are large boxes used to cool hot water from the condenser. We have to check the water level and ensure the proper working of the float valve before switching on the chiller.

One of the important issues in cooling tower operation is keeping proper levels of circulating water in the tower.

Float valves maintain the water level in the cooling towers. These valves detect the changes in water level and open and close accordingly. These valves are similar to the ones we find in toilet tanks.

If you look inside your toilet tank, you will find an air-filled ball connected to a rod. When you flush, the ball falls with the water level, opens the valve and water starts flowing into the tank.

The ball rises with the water up to a certain point until the valve is closed. In the same way, the float valve maintains the water level in a cooling tower.


We need to tighten all the electrical connections with a screwdriver in the control panel. We’ve to pull the wires and make sure that there are no loose connections. If we find any loose connections, we’ve to tighten the screw terminals down onto the wires.

A chiller technician must do preliminary checks before starting any chiller. Preliminary checks ensure the efficient operation of a chiller. It will let the technician find malfunctions and hazards if there are any.


Question #1: Before attempting to operate any chiller, a technician should:

  1. have worked on residential air conditioning systems

  2. become familiar with the equipment

  3. have done troubleshooting for the equipment

  4. All the above

Scroll down for the answer...

Answer: become familiar with the equipment

Before attempting to operate any chiller, a technician should become familiar with the equipment.

Question #2: From the below picture, which part of the chilled water lines is not insulated well or damaged insulation?

You’ve observed the whole picture to find the damaged insulation. In the same way, we have to go around a chiller plant and inspect the evaporator and all the chilled water pipelines to find damaged insulation.

Question #3: Which of the following lubricates the chiller's internal components during operation?

  1. Chilled water

  2. Refrigerant

  3. Compressor oil

  4. Steam

Scroll down for the answer...

Answer: Compressor oil

Compressor oil used in a chiller compressor lubricates internal components during operation.

Question #4: Which of the following valve keeps the water level in the cooling tower?

  1. Reversing valve

  2. Float valve

  3. Expansion valve

  4. Globe valve

Scroll down for the answer...

Answer: Float valve

A float valve keeps the water level in the cooling tower.


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