Choosing the right size chiller is an important part of designing a reliable process cooling system. A chiller that is too small may not be able to keep your process at the required temperature, while a chiller that is significantly oversized can cost more to purchase and may not operate as efficiently as expected.
But how do you know what size chiller you need?
For many customers, the answer is not as simple as looking at a machine’s specifications or choosing a chiller based on horsepower. The correct chiller size depends on several factors, including the equipment being cooled, how much heat the process produces, the temperature requirements, the amount of fluid being circulated, and how the system will be used.
Fortunately, you don’t need to know all of these calculations yourself to get started.
A qualified chiller manufacturer can help determine the requirements of your application and recommend the appropriate cooling capacity and system configuration.
What Does “Chiller Size” Actually Mean?
When someone refers to the “size” of a chiller, they are usually talking about its cooling capacity.
Chiller capacity is commonly measured in:
- BTU/hr
- Tons of cooling
- Kilowatts (kW)
One ton of refrigeration represents approximately 12,000 BTU/hr of cooling capacity.
For example, a 10-ton chiller has a nominal cooling capacity of approximately 120,000 BTU/hr.
However, a chiller’s tonnage alone does not tell the whole story. A 10-ton chiller may provide different actual performance depending on the temperature it is expected to produce, the ambient conditions, the type of fluid being cooled, and other operating conditions.
That’s why proper chiller sizing involves more than simply choosing a number of tons.
Start With Your Process
The best place to begin is by understanding what you need the chiller to cool.
You may not know the exact amount of heat your equipment produces, but you probably know what the chiller will be used for.
For example, you may need to cool:
- Manufacturing equipment
- CNC machines
- Plastic injection molding equipment
- Laser equipment
- Hydraulic systems
- Food processing equipment
- Brewery equipment
- Chemical processing equipment
- Refrigeration systems
- Laboratory equipment
- Other industrial processes
Simply knowing what equipment or process needs cooling gives a chiller manufacturer an important starting point.
From there, the manufacturer can help determine the cooling requirements of the application.
How Much Cooling Capacity Do You Need?
The most important factor in determining chiller size is the heat load.
Heat load is essentially the amount of heat that needs to be removed from your process.
Some equipment manufacturers provide this information directly. In other cases, it may need to be calculated based on the equipment and process.
You may hear terms such as BTU/hr, cooling load, heat load, tons, or kW when discussing chiller capacity.
Don’t worry if these terms are unfamiliar.
You don’t necessarily need to calculate your own heat load before contacting a chiller manufacturer. Providing information about the equipment you are cooling, how it operates, and what you are trying to accomplish can give an experienced manufacturer enough information to help determine the appropriate capacity.
What Information Should You Provide?
The more information you can provide about your application, the easier it is for a chiller manufacturer to recommend the right system.
Don’t worry if you don’t have every specification. Start with what you know.
Useful information may include:
What are you cooling?
Tell the Legacy what equipment, process, product, or system needs to be cooled.
How is the equipment being used?
Explain whether it operates continuously, intermittently, seasonally, or at varying production levels.
What temperature are you trying to maintain?
If you know the desired temperature, provide it. If you don’t, the equipment manufacturer or chiller specialist may be able to help determine what temperature is appropriate for your application.
What type of cooling fluid will be used?
Many systems use water, while others use a water/glycol mixture or another heat-transfer fluid.
What are the environmental conditions?
For example, an air-cooled chiller installed in a hot manufacturing facility may have different requirements than one operating in a temperature-controlled environment.
Are you replacing an existing chiller?
If you are replacing an existing system, information from the current chiller can be extremely helpful. The model number, capacity, operating temperature, fluid type, and any performance problems can all provide useful information.
Are you planning to expand?
If you expect production to increase or additional equipment to be added, let the manufacturer know. Future requirements can sometimes be considered during the initial system design.
What If You Don’t Know Your Heat Load?
This is one of the most common questions customers have when looking for a chiller.
You may know that your machine needs cooling, but not know how many BTUs of heat it produces.
That’s okay.
A chiller manufacturer can often work with the information you do have to help determine the approximate cooling requirement.
Depending on the application, they may ask about the equipment’s horsepower, electrical input, production rate, fluid flow, operating temperatures, or other specifications.
In some cases, the equipment manufacturer may also be able to provide heat-load information.
The goal is to gather enough information to develop a reasonable understanding of the cooling demand before selecting the chiller.
Why Chiller Sizing Is Important
Proper sizing is important because the chiller needs to keep up with the heat generated by your process.
If a chiller is undersized, it may run continuously while struggling to maintain the desired temperature. This can result in higher operating temperatures, reduced process performance, and potentially increased wear on the equipment.
If a chiller is oversized, the system may cost more than necessary and could operate inefficiently when the actual process load is significantly lower than the chiller’s capacity.
The goal is not necessarily to choose the largest chiller available.
The goal is to select a chiller that provides the appropriate amount of cooling capacity for the application.
Don’t Size a Chiller Based on Horsepower Alone
One common mistake is assuming that a piece of equipment’s horsepower directly determines the required chiller size.
Horsepower can provide useful information, but it does not necessarily tell you exactly how much heat the chiller needs to remove.
Two pieces of equipment with similar horsepower ratings may have very different cooling requirements depending on how they operate and how much heat is transferred into the cooling system.
The same applies to simply replacing an existing chiller with another unit of the same nominal tonnage.
The original system may have been oversized, undersized, or operating under different conditions than your current process.
Whenever possible, the complete application should be evaluated before selecting the replacement or new chiller.
What About Future Production?
Your current cooling requirements may not be the same as your future requirements.
If you are planning to add equipment, increase production, or expand your operation, tell your chiller manufacturer.
In some applications, selecting additional capacity during the initial installation may make sense. In others, a modular system or multiple chillers may be a better solution.
Planning ahead can help prevent having to replace an undersized chiller when production increases.
At the same time, it is important not to dramatically oversize a system simply because you may expand someday. An experienced chiller manufacturer can help determine the best approach based on your current and anticipated requirements.
When Should You Ask a Chiller Expert?
If you aren’t sure what size chiller you need, talk to a Legacy representative before purchasing equipment.
A good manufacturer should be able to ask the right questions about your process and help determine what information is needed to properly size the system.
You don’t need to be a refrigeration engineer to start the conversation.
Even basic information such as:
“I need to cool this machine, it runs eight hours a day, and I’m currently using a 50-gallon water loop”
can give a Legacy sales representative a starting point.
From there, additional questions can help determine the appropriate cooling capacity, temperature range, flow requirements, fluid type, and chiller configuration.
For more specialized applications, working directly with a manufacturer can also help identify requirements you may not have considered.
The Right Chiller Is About More Than Tonnage
Proper chiller sizing is not simply a matter of deciding whether you need a 5-ton, 10-ton, or 20-ton unit.
The correct system needs to match the requirements of the process.
That includes the amount of heat that needs to be removed, the required operating temperature, fluid type, flow requirements, environmental conditions, and how the equipment will be operated.
For some applications, additional considerations such as a buffer tank, pump selection, multiple cooling circuits, or specialized controls may also be important.
This is why getting professional input during the selection process can be valuable.
Need Help Determining What Size Chiller You Need?
You don’t have to know every specification before contacting Legacy Chillers.
If you know what you need to cool, how the equipment operates, and what you are trying to accomplish, that is a good place to start.
The team at Legacy Chillers can help evaluate your application and determine the appropriate cooling capacity and chiller configuration for your process.
Whether you need an air-cooled, water-cooled, packaged, split-system, tank, or tankless process chiller, proper sizing starts with understanding your application.
Not sure what size chiller you need? Contact Legacy Chillers and let our team help you determine the right cooling solution for your process.