When selecting a chiller for your cooling needs, understanding the metrics of its capacity, particularly its BTUs, watts, and tons of refrigeration is crucial. This guide will help you understand what these measurements mean and how you can use them to calculate the appropriate refrigeration capacity and size for your needs.
What Is a Chiller?
A chiller is a refrigeration system used for cooling industrial spaces, tools, and process fluids by circulating a heat-absorbing refrigerant and ultimately removing heat from the material. Industrial chillers are widely used to regulate the temperature in several industrial processes, such as food processing, injection moulding, oilfield production, and metal plating.
The Importance of Understanding Chiller Capacity
Chiller capacity refers to the ability of a cooling system to remove heat. This is typically measured in BTUs per hour or watts. Understanding these units will help you identify the appropriate chiller size or unit for your needs or application.
What are BTU, Watts, and Tons of Refrigeration?
Various equipment models have different chiller capacities, some of which are expressed in different units of measurement. Understanding the chiller capacity in terms of BTUs, watts, and tons of refrigeration is essential for selecting the right equipment for your cooling needs.
British Thermal Unit (BTU)
The BTU rating is used to identify the chiller’s ability to effectively cool a given material, making it one of the most significant factors to consider when selecting an appropriate unit. While it is more commonly used in the United States, it is also used by several Australian equipment manufacturers to quantify the cooling or heating capacity of an HVAC system. One BTU is equal to the energy needed to increase one pound of water by one degree Fahrenheit. In other units of measurement, 1 BTU is also equivalent to:
- 1 kW = 3,412 BTU
- 1 Ton = 12,000 BTU
- 1 HP (Horsepower) = 9,000 BTU
The higher the BTU rating, the more cooling power the chiller has. Conversely, equipment with a lower BTU rating may struggle to cool your sample or material. However, it is important to note that equipment with higher BTU ratings also requires lots of power, which may also translate to higher operational costs. Balance the BTU rating with your cooling requirements as well as operational costs to make an informed decision.
Watts
A watt (W) is a unit of power that measures the power of an appliance and calculates the energy consumption. It indicates the power needed by the chiller for heat removal. For watt-to-BTU per-hour conversions, 1 watt is equal to 3.41 BTU/h.
Tons of Refrigeration (TR)
A ton of refrigeration (TR) identifies the heat extraction capacity of a cooling system. Generally, TR is described as the quantity of heat required to freeze or melt 1 short ton of ice at 0ºC in 24 hours. It is approximately equal to 12,000 BTU.
BTU to Watt to TR Conversion
BTU per hour | Kilowatt (Watt) | Tons of Refrigeration |
6,000 | 1.76 kW (1,760 W) | 1/2 |
12,000 | 3.52 kW (3,520 W) | 1 |
18,000 | 5.28 kW (5,280 W) | 1 1/2 |
24,000 | 7.03 kW (7,030 W) | 2 |
30,000 | 8.79 kW (8,790 W) | 2 1/2 |
36,000 | 10.6 kW (10,600 W) | 3 |
42,000 | 12.3 kW (12,300 W) | 3 1/2 |
48,000 | 14.1 kW (14,100 W) | 4 |
54,000 | 15.8 kW (15,800 W) | 4 1/2 |
60,000 | 17.6 kW (17,600 W) | 5 |
How to Choose the Right Chiller Capacity?
Choosing the right chiller capacity is crucial for maintaining optimal performance, efficiency, and longevity of your cooling system. To ensure your prospective chiller meets your specific requirements, here are some of the key factors to consider
Cooling Load of the Space or Equipment
The cooling load refers to the total amount of energy that needs to be removed from the space or equipment to achieve and maintain the desired temperature. Depending on the equipment type and usage, ambient temperature, potential heat sources within the space, and heat transfer coefficients, the cooling load can vary.
Desired Temperature Difference
Temperature difference represents the difference between the inlet (return air) and outlet (supply air) temperatures of the coolant in the chiller. This parameter is important in determining the heat load that the chiller needs to remove and influences the overall efficiency and performance of the cooling system.
Ambient Temperature and Humidity
Ambient temperature refers to the temperature of the surrounding air where the equipment is stored or placed. Higher ambient temperatures and humidity levels can increase the cooling load of the chiller, forcing it to operate more intensively to remove the excess heat and moisture from the air. This can then result in increased energy consumption and higher operational costs.
Safety Factor
Always include a safety margin in your calculations to account for unexpected increases in heat load or fluctuations in operating conditions. It is recommended to place a safety margin of 10-20% in your calculations to ensure the chiller can handle unexpected heat gains and maintain its efficiency.
Energy Efficiency of Chillers
Generally, a higher energy efficiency ratio (EER) means better chiller efficiency. Chillers with high EER consume less power for the same cooling output, leading to lower operating costs and reduced environmental impact. Consider looking for equipment with an Energy Rating Label to ensure you’re choosing a chiller that meets high-efficiency standards.
Maintenance Requirements
It’s important to regularly maintain and clean the chiller to sustain its efficiency and extend its lifespan. Consider the ease of maintenance and availability of service support in case of equipment issues or breakdowns. Check if the manufacturer offers support plans that include regular maintenance, repairs, and emergency services.
Cost Considerations
When selecting a chiller, do not only consider the initial cost or the price. Also take into account the long-term operational and maintenance costs. Usually, energy-efficient units have higher upfront costs but can save money in the long run through reduced energy consumption. Identify your budget for both the purchase and ongoing operational costs, and choose equipment that provides the best balance of cost, efficiency, and performance.
How BTU/hr Rating Helps in Chiller Selection
To calculate the chiller sizing and identify the chiller capacity you need, follow the formula below:1
1. Calculate the temperature difference (ΔT°C)
ΔT°C or °F = Inlet water temperature — Required water temperature
2. Calculate BTU/hr
BTU/hr = Gallons Per Hour x 8.33 x ΔT°C or °F
3. Calculate tons of refrigeration
Tons = BTU/hr ÷ 12,000
4. Oversize the chiller by 20% for safety factor
Ideal size in Tons = Tons x 1.2
5. Then, you have the ideal chiller size!
Make the Right Choice for Maximum Cooling Efficiency
Choosing the right chiller capacity involves a careful evaluation of several factors, including the cooling load, desired temperature difference, ambient conditions, energy efficiency, cost considerations, and maintenance requirements. By thoroughly assessing these factors, you can ensure that your chiller can accommodate your cooling needs without compromising long-term reliability and performance.
Across International offers various recirculating chillers that meet any of your application requirements. Our selection includes chillers with different volume options that range from 3 to 50 litres. As an ISO 9001:2008-certified manufacturer, we ensure that all of our equipment is also CE-certified so you can rest assured that you’re investing in products that are of high quality and meet safety standards.